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  • 2022-06-27世界捷径:巴拿马运河的运作方式This video was made possible by Brilliant.本视频由Brilliant制作发行 Learn with Brilliant for 20% off by being one of the first 200 to sign up通过brilliant.org/Wendover注册Brilliant的 at brilliant.org/Wendover.前200名用户可享八折优惠 The purpose of the Panama Canal is pretty easy to understand.巴拿马运河的用途显而易见 It turns a journey of this into this.它把旅程从这样 变成了这样 It brings the US west coast closer to Europe,使美国西海岸到欧洲的路程更近 and it brings the US east coast closer to Asia.同时也缩短了美国东海岸到亚洲的路程 These rather short 180 foot or 55 meter wide trenches are, combined,这些相当短的180英尺或55米宽的海沟连在一起 perhaps the single most important and most influential waterway on earth.可能是世界上最重要最具影响的水利工程 That’s because the entire shipping industry worldwide is shaped by the Panama Canal.因为全世界的航运业都受巴拿马运河影响 Hundreds of years ago,几百年前 the opportunity of a canal across the narrow country of Panama was identified.人们偶然发现可以跨越巴拿马地峡开凿一条运河 After a few earlier false starts最初几次尝试失败后 the Americans went down to Panama in 1903,1903年 美国人来到巴拿马 signed a fairly dubious treaty granting them land,签署了一份相当可疑的土地使用条约 dammed up a river to make an artificial lake,美国人拦河筑坝造人工湖 dug a trench from that lake to the Pacific, dug a trench from that lake to the Atlantic,以湖为连接点 打通了太平洋和大西洋 and $13 billion耗资130亿美元 and 5,600 worker fatalities later,折损人力5,600人 the canal was done.终于建成了运河 It officially opened the Pacific to the Atlantic on August 15, 19141914年8月15日 太平洋与大西洋正式通航 as the first commercial ship, the SS Ancon, sailed through.SS Ancon是驶过运河的第一艘商船 Now, the Panama Canal is not just one straight shot from ocean to ocean.现在两洋之间的巴拿马运河并不是“一马平川” That’s because the artificial lake they created, Gatun Lake,这是因为人工修建的加通湖 is 85 feet or 26 meters above sea level.其海拔85英尺(26米) So, cargo ships, which can weigh more than a billion pounds,所以 重量超过10亿磅的货船 need to get up those 85 feet or 26 meters需要被迫抬高85英尺(26米) and then back down again然后再下降相同高度 to transit from ocean to ocean.才能从一个大洋到另一个大洋 Like most canals, to do this,和大多数运河一样 the Panama Canal uses locks.巴拿马运河也使用水闸 From the Atlantic side, for example,例如 从大西洋出发 a ship will be pulled into the first lock by the tug trains on each side of the canal,一艘船通过拖轮火车被拖入第一个水闸 the downstream gate will close,下游的闸门关闭 water from upstream will be fed in to fill the lock上游的水同时注入到闸中 the boat will float up,船上浮 then once the water level rises to match that of the next lock,等水位上升到下一个水闸的高度 the gate will open,闸门打开 and the ship will be pulled into the next lock.船被推到下一个水闸处 Then, the gates will close,接着 第二个闸门关闭 the water level will rise again,水位再次上升 the gates will open,下一个闸门打开 then this will all happen one more time船体再一次抬高 until the third lock直到第三个水闸 raises the ship to the water level of Gatun Lake—将船体升高至加通湖的水位高度 those 85 feet or 26 meters above sea level.此时海拔85是英尺或(26米) Believe it or not,你相信吗 it is these three locks exclusively正是这三个水闸 that limit what size a large portion of the world’s container ship fleet can be.限制了世界上很多集装箱船队的尺寸大小 A ship has to be under 1,200 feet or 366 meters long船长要小于1200英尺(366米) and 168 feet or 51 meters wide宽度小于168英尺(51米) to be accepted in the Panama Canal才能通过巴拿马运河 and so a huge proportion of the world’s ships are built to be exactly this size.所以大多数世界货轮都是不会超过这个尺寸的 This class of ship is called NeoPanamax这类船被称为新巴拿马型 or New Panamax or Post Panamax新-巴拿马型或后巴拿马型 depending on who you ask.叫法不一 Of course, there are certainly ships larger than the NeoPanamax size.当然 肯定有比新巴拿马型大的船 The Panama Canal has a size limit of巴拿马运河的货轮的大小限制 about 15,000 TEU or twenty-foot equivalent units.约为15000标准箱或20英尺当量单位 That’s a measure of a ship’s capacity承载力的衡量是看 based off how many of these twenty-foot containers they could carry.一艘船可以放多少20英尺长的集装箱 Now, the largest container ship in existence, the OOCL Hong Kong,最大的集装箱船现存于东方海外香港有限公司 has a capacity of over 21,000 TEU.它可以承载21000多个集装箱 This ship, like many of those larger than 15,000 TEU,和那些超过15000集装箱的船一样 exclusively keeps to the east Asia to Europe route这艘船的行驶路线是东亚到欧洲 as it can’t efficiently make trips that require transit between the Pacific and Atlantic因为它无法途径巴拿马运河由太平洋直接进入大西洋 since it would have to circumnavigate South America.所以它必须绕过南美洲 But it was really not long ago不久前 that the largest ships that could go through the Panama canal可以通过巴拿马运河最大船 were far smaller than the current 15,000 TEU size.还远远小于目前的15000集装箱的大小 You see, up until 2016,2016年以前 the Panama canal could only fit ships smaller than 5,000 TEU.巴拿马运河只能容纳5000集装箱以下的船 That’s because up until 2016,因为2016年之前 these didn’t exist—the Panama canal’s new locks.巴拿马运河没有安装新的水闸 The old locks can only only fit a ship 106 feet or 32 meters wide but still,旧水闸只适合106英尺(32米)宽的船 given the enormous importance of this waterway,但鉴于这条运河的重要性 ships were still then built specifically to fit through.船只建造会以能通过这条运河为标准 In fact, 50% of the old lock’s users事实上 50%的旧船闸用户 were exactly as wide as this width limit suggested他们的船宽正好是限宽 they were likely built for exactly that purpose.这些船很可能就是为此建造的 This was a problem for the Panama canal, though,然而巴拿马运河还需要面对一个问题 because, believe it or not, the canal has competitors.就是市场竞争问题 It all has to do with geography.这就要说说地理知识了 When traveling from east Asia to the US east coast,从东亚航行到美国东海岸 which is one of the busiest shipping routes in the world,这条航线是世界上最繁忙的航线之一 it really is not all that much further to go west than east.但从东亚出发 往西走并不比向东走远多少 Going from Hong Kong to Newark, for example,比如 从香港到纽瓦克 the distance heading west through the Indian ocean,向西穿过印度洋 Suez Canal, Mediterranean, and Atlantic经苏伊士运河 地中海 大西洋 is only a few hundred miles or kilometers longer than 这段路程只比向东途径太平洋 going east across the Pacific and through the Panama Canal.和巴拿马运河长几百英里(几公里) Meanwhile, the Panama canal is not cheap.而且 穿过巴拿马运河并不便宜 They charge a $90 toll per twenty foot container20英尺的集装箱需要90美元通行费 meaning that most ships, carrying thousands of loaded containers,对大多数载满成千上万货物的船只来说 pay hundreds of thousands of dollars for just a single transit.单程通行费就需要支付数上万美元 With the new locks and their higher capacity,有了新船闸后运载能力提高了 single ships can possibly be assessed如果一艘达到限行标准的船满载而行 more than $1 million per transit if they’re the largest size, fully loaded.其单程通行费将超过100万美元 The Suez canal, meanwhile, typically charges lower tolls.而苏伊士运河通常收取较低的通行费 A ship sailing that Hong Kong to Newark route一艘从香港到纽瓦克航线的船 therefore might choose to take the slightly longer route via the Suez canal可能会选择稍长的路线 经过苏伊士运河 versus the Panama canal而不是拿马运河 as, in the end, when you consider the tolls,因为 在考虑通行费后 it might end up being less expensive.经苏伊士运河的路线可能更便宜 Now, both canals are constantly changing their fees in order to compete with the other现在竞争关系下的两条运河都在不断调整价格 but still, throughout the past decade,尽管如此 在过去的十年中 the Suez Canal seems to maintain a slight edge in cost.苏伊士运河似乎在成本上保持着微弱优势 The Panama Canal’s other competitor, though, is trains.然而 巴拿马运河的另一个竞争对手是火车 For the crucial east Asia to US east coast route,关键的东亚至美国东海岸航线 going through the Panama canal经过了巴拿马运河 while much faster than circumnavigating the continent,比陆上环游欧洲大陆快得多 is still not a direct route.但仍然不是最近路线 On the Hong Kong to Newark route,从香港至纽瓦克 the Panama canal represents经过巴拿马运河就意味着 an almost 3,000 mile or 5,000 kilometer diversion from the alternative crossing the US by land.比从陆路穿越美国多行驶 3000英里(5000千米) It is pretty standard practice明智的做法是 to ship cargo from east Asia to Los Angeles把货物装船从东亚运到洛杉矶 and then load it up on trains to get to the US east coast.再通过火车运至美国东海岸 While overall this usually ends up a little more expensive虽然总的来说 这通常要贵一些 than going through the Panama Canal,但相比于经过巴拿马运河 it saves about a week in transit time它节省了一个星期的运输时间 and, for many shippers, this is worth it.对许多托运的人来说这一点弥足珍贵 Trains, with their relatively low cost,火车以其相对较低的成本 represent a considerable competitor to the canal,成为巴拿马运河的强大竞争对手 and it is the competition with both these and the Suez canal与火车以及苏伊士运河的竞争 that pushed the Panama Canal to make an expansion.推动了巴拿马运河的发展 That’s why they spent $5.4 billion所以管理方斥资54亿美元 to build these bigger locks that could fit larger, 15,000 TEU ships.建造更大的水闸 可容纳15000集装箱的船 This would let more of the world’s shipping fleet through and these bigger ships,这可使更多航运船队和更大的船只通过 thanks to economies of scale, have lower cost per container由于规模扩大 因而每个集装箱的通行费更低 which helps make the canal more attractive in comparison the its trains or Suez competition.这就更能与火车和苏伊士运河相抗衡 Now, this expansion is a great example of the butterfly effect.这个扩建印证了蝴蝶效应 In one instance,举个例子 because the Panama Canal widened its size limit by a few dozen feet,因为巴拿马运河的限高增加了几十英尺 the state of New Jersey had to spend $1.7 billion to raise a bridge by a few dozen feet.所以新泽西州不得不花费17亿美元将一座桥抬高几十英尺 You see, in order to get to much of the port of Newark, which is one of the largest and busiest in the US,原因就是 要想抵达美国最大最繁忙的港口纽瓦克港 ships have to pass under the Bayonne bridge.船只必须经过巴约纳大桥 As a huge proportion of the shipping traffic to the US east coast goes through the Panama Canal,巴拿马运河是美国东海岸的航运枢纽 before the new set of locks,因而在新的船闸建成之前 many of the ships that wanted to use the port of Newark were the smaller, 5,000 TEU size通过纽瓦克港的船只承载量需要在5000集装箱以下 which could all fit under the Bayonne Bridge,这样才能通过巴约纳大桥 sitting at 151 feet or 46 meters above the water.而该桥高151英尺(46米) With the canal expansion project,运河扩建工后 though, more ships would start making their way to Newark更多的船只驶向纽瓦克港 that would be too large to fit under the Bayonne bridge.但这些船太大了 无法通过巴约纳桥 Therefore, in order for the port of Newark to stay competitive,为了保证纽瓦克港的竞争力 they just had to raise that bridge.政府不得不抬高这座桥 Beyond that,除此之外 all up and down the US east coast,美国东海岸附近 from Miami to Savannah to Charleston to Baltimore and to New York,从迈阿密到萨凡纳 再到巴尔的摩和纽约 ports quickly spent millions and billions of dollars to build facilities沿途港口花费了数百万美元进行建设 that would fit the bigger ships in time for the opening of the new canal locks.以便及时适应新运河开闸后接踵而来的大船 Still today, though,然而 直到今天 many ports on the east coast do not have the depth and facilities许多东海岸的港口基础设施仍然不够完善 needed to handle these NeoPanamax ships.不能满足这些新巴拿马船的需求 This, though, presents an opportunity for the Caribbean.然而 这对加勒比地区来说是一个机会 Deep-water ports in the Caribbean are developing themselves into major transshipment hubs.加勒比的深水港正发展成为主要的转运中心 What these are ports where larger ships, like the largest 15,000 TEU container ships这里有些港口可供15000 集装箱的船只通过 that can now go through the canal,它们可以通过运河 will unload their cargo which will then be loaded again onto smaller ships卸下货物 然后再装到较小的船上 bound for smaller ports closer to the cargo’s destination up and down the east coast.前往东海岸附近更靠近目的地的小港口 Huge amounts of foreign money are flowing into the Caribbean大量的外国资金流入加勒比地区 to develop these transshipment hubs.以开发这些转运中心 CMA CGM, a shipping company from FranceCMA CGM是一家法国的航运公司 that ranks as the world’s third largest在全球排名第三 operates the port of Kingston, Jamaica.经营着牙买加金斯敦港 DP World, from the UAE,来自阿联酋的世界港口公司 operates the port of Caucedo in the Dominican Republic.经营多米尼加共和国考科多港 Meanwhile, the port of Freeport, in the Bahamas,与此同时巴哈马的自由港 is operated by Hutchison Port Holdings from Hong Kong.由香港和记港口控股公司运营 All of these companies and more have and continue to focus on expanding these Caribbean ports这些公司和更多后继者将继续扩建这些加勒比港口 to suit the increased traffic making its way through the Panama Canal, into the Caribbean,以应对通过巴拿马运河进入加勒比海 and eventually to its destination on the east coast.最终抵达东海岸的船只 Sometime soon, though, something could happen不久的将来 可能发生一件事 that would be simultaneously great for the Caribbean ports这件事对加勒比港口来说是件好事 but terrible for the Panama Canal.但对巴拿马运河来说很可怕 You see, two countries to the north of Panama is Nicaragua.你看 巴拿马北面是尼加拉瓜国 By linking both the Atlantic and the Pacific to the large Lake Nicaragua,尼加拉瓜湖可将大西洋和太平洋连接起来 one could have another connection between the oceans.这将成为连接两大洋的又一通道 There has been a long history of attempts to build this canal,人们很久前就尝试修建这条运河 most recently in the past decade with a failed scheme by a Chinese billionaire.过去十年就有一位中国亿万富翁的策划以失败告终 Given that this failure was rather recent鉴于最近这次失败 there are no current construction plans,目前没有建设计划 but at least somewhere,但至少 the world is going to need more canal capacity between the Pacific and the Atlantic.太平洋和大西洋之间将会有更多的运河 The shipping industry is growing at a solid rate of about 5% annually航运业正以每年5%的速度稳步增长 and the Panama canal can only expand so much.巴拿马运河也只能扩建这么多 One issue is that the Panama Canal could literally run out of water.而且巴拿马运河可能会耗尽水资源 You see, each time the canal’s locks open,你看 每次运河的水闸打开 millions of gallons of water flow out and downstream.数百万加仑的水就会流到下游 Usually this is not a problem一般来说 这没啥大问题 because the lake upstream has enough water,因为上游的湖水量充足 but sometimes,但有时 during periods of reduced,在降雨量减少的时期 there just won’t be enough water水量匮乏 无法同时保证 to both release the amount needed to operate the locks操作船闸的过程中需要的水 and keep the lake at a deep enough level for the largest ships to transit.以及大船过境需要的足够深的湖水 At these times, which included much of Spring 2019,在这些时候 就像2019年春季 the canal will have to place restrictions on how much weight cargo ships can carry运河不得不限制货船的承载量 as this will affect how deep they sit in the water.因为承载量将影响到船只吃水量 They’ve attempted to limit the effects of this他们试图通过安装一个系统以回收一些用来操作水闸的水 by installing systems to recapture some of the water used to operate the locks来控制这种影响 and there are also potential plans to build an additional upstream dam to create an additional reservoir,同时也有一个在上游拦坝建立新水库的计划 but these problems are only expected to worsen但这些问题仍可能会更糟 as climate change exacerbates the severity of droughts in the region.因为气候正在进一步恶化 All told, what happens in Panama affects the world.总之 在巴拿马发生的事情影响着世界 If a drought in Panama restricts the throughput of the canal,如果干旱限制了巴拿马运河的吞吐量 the world economy will feel it.世界经济将会受到影响 That’s because shipping is what connects the world’s economy因为航运是连接世界经济的纽带 and the Panama canal is one of the most important connectors in shipping.而巴拿马运河是重要的航运中心之一 The canal effectively brings the economies on one side closer to those on the other运河有效地拉近了两岸经济的距离 and so, no matter what happens,所以 无论发生什么 it will continue to serve as the world’s shortcut.它都将继续作为世界的捷径 Now, one of the things that those working at the Panama Canal现在 在巴拿马运河工作的人 need to understand is how water works.需要了解水是如何发挥作用的 As in, how weather works,比如 天气的变化 how the water cycle works,水循环的原理 how tides work—all of these things潮汐是如何变化的——所有这些事情 are also, though,当然 concepts that you can learn about in Brilliant’s Physics of the Everyday course.你可以从Brilliant的日常物理课中学到很多 Brilliant is the best place to learn complex thingsBrilliant是学习复杂事物的最佳场所 such as physics or really any field of math and science.比如物理或数学和科学的任何领域 Not only do they have all their fantastically designed courses,他们不仅有自己设计的课程 they also have, in the goal of helping you get a little smarter every single,还有一系列的日常挑战 a series of daily challenges.能帮你变得更聪明 In just five minutes while you’re waiting for the subway, the toaster, the doctor, or whatever,在你等地铁 烤面包 等医生的几分钟 you can challenge yourself with one of these你可以挑战其中之一 and then, if it piques your interest,如果你感兴趣的话 each is linked to one of their full length courses as well.每个挑战都有相对应的完整课程 You can try Brilliant你可以试用Billiant and support the channel by signing up for free at brilliant.org/Wendover.通过brilliant.org/Wendover免费注册它就是对本频道的支持 Also, though, the first 200 people that go to that link当然 前200名访问该链接的用户 will get 20% off the annual Premium subscription.将获得八折的年度优惠
  • 2022-06-27鲜为人知的自行车奥秘Most people don’t know how bicycles actually work.多数人并不了解自行车的实际工作原理 “Let’s try it again.”“再试试看” So we modified this bike to prove it.于是我们改造了这辆车进行验证 This video is sponsored by KiwiCo.本视频由KiwiCo赞助 More about them at the end of the show.更多信息请看节目最后 “When you’re riding a bike and you want to turn left,“当你骑着自行车想要左转时 I think most people just imagine我想多数人会认为 you turn the handlebars to the left.只要将车把向左转即可 This is a bike to test whether that is true.我用这辆车测试下这想法对不对 And it’s made by my friend Rick here.这是我朋友Rick改造的 And he’s got a radio controller that allows him他有一个无线电遥控器 to lock out the steering to one side.能把车的转向锁定在一个方向 So, what he’s gonna do is as I’m biking,那接下来他要做的就是 he’s gonna pick whether I can turn either to the left or to the right.决定我骑车时 能否左转或右转 So, go for it.”那我们开始吧” “I’m giving it a left turn.“我先设置左转 It pulls the pin out,插销被拉了出来 but you can see that you can still fully steer after I’ve pulled the pin out.”你看我拉出插销后 你仍然可以转向” – I’ve armed it. There’s where it locks. – OK.– 装好插销 转向就锁住了 – 明白 “Now, that’s when your LED comes on“现在 哪边的LED灯亮起 and that just says turn that way.”就说明转向哪边” – Turn left. – Yeah.– 左转 – 没错 “And if I try to turn right.”“如果我想右转” – You can’t. – I can’t.– 你转不了 – 不行 “And if I try to turn left.”“如果我尝试左转” – You can. – I can.– 你可以左转 – 我可以 “So the question is can I“那么 问题在于我能否 successfully execute this left-hand turn?”成功实现这次左转呢?” – Should we give it a shot? – I mean,– 要不咱们试试看? – 就是说 he’s not gonna tell me whether it’s left or right,他不会告诉我左转还是右转 so I have to look at the LED to know which way I can still turn.我得看LED灯判断还能朝哪边转弯 – You let me know when you’re ready. – Okay.– 准备好了告诉我 – 好了 [exclaims] No![惊呼]别倒啊! “That was meant to be a turn to the right,“本来是要向右转的 but there was no chance in hell.”但压根儿不可能” “Left.”[exclaims]“左转”[惊呼] – Right. – All right. [exclaims]– 右转 – 好吧 [惊呼] “Right, right, right! God!”“右转 右转 右转!天啊!” If you look closely, you can see the problem.如果你仔细观察 就会发现问题所在 Here, I’m trying to turn right此时 我正要右转 but steering that way puts me off balance.但这样转让我失去平衡 If you could ride this bicycle,如果你骑上这辆车 you would find it’s impossible to turn left without first steering right,就会发现 不先向右转 是不可能实现左转的 and it’s impossible to turn right without first steering left.当然 不先向左转 也是不能实现右转的 This seems wrong.这似乎是个谬论 I think most people believe you turn a bike我想多数人会认为自行车转向 simply by pointing the handlebars只需将车把朝着 in the direction you want to go.你想要前进的方向就行 After all, this is how you drive a car.毕竟 你也是这样开汽车的 Point the front wheels any direction you like将前轮朝着你想要前进的方向 and the car just goes that way.汽车就会往那个方向行驶 But the difference with a bicycle is不过自行车的不同之处在于 steering doesn’t just affect the direction you’re headed,转向不仅影响你前进的方向 it also affects your balance.还影响平衡性 Imagine you want to make a right turn,想象一下 你想右转 so you steer the handlebars to the right.所以你将车把转向右边 What you’ve done is effectively steered the bike out from under you.这么做 实际上等于让车失衡 So now you’re leaning to the left,此时你正向左倾斜 and the ground puts a force on the bike to the left而地面给自行车施加向左的力 so the only way not to fall所以避免摔倒的唯一方法 is to steer the bike to the left.就是将自行车转向左边 You have made a left turn.你就实现了左转 If you really wanted to turn right,相反 如果你要向右转 you first have to counter-steer to the left你得先反向控制自行车向左转 so you can lean right into the turn.这样就能向右倾斜实现右转 This is something anyone who rides a bike knows intuitively这一点任何骑车的人都自然而然知道 but not explicitly.但又不明就里 “Turn left!”“向左转!” Film someone riding a bike towards you拍摄面向你骑车的人 and tell them which direction to turn并告诉他们朝哪边转 and you will find that they counter-steer你会发现他们不加思索地 without even thinking about it.先朝反方向转把手 “Hard left!”“向左急转弯!” “When you’re riding a bike,“你骑车时 it’s exactly the same as what we call an inverted pendulum道理就和我们所说的倒立摆 or balancing a broomstick on your hand.或平衡手中扫帚是完全一样的 If I’m balancing it and I just start walking toward you,如果我平衡扫帚时 只是直接走向你 it will always fall away from you.扫帚就会倒下来 If I want to walk towards you, it’s easy enough to do如果我想走向你 其实很容易 and people inherently know how to do it.大家都知道 If I pull it backward, I can now start walking that way.先把它往后拉 就能开始向前走了 I have to initiate the lean to turn into it.”我必须先倾斜 才能移动” If you want to move the pendulum somewhere,如果你想向某个方向移动扫帚 you first move the base in the opposite direction.就要先反向移动其底部 And now the pendulum is leaning in the direction you want to go,现在长柄扫帚正倒向 你要去的方向 so you can move with it.那么你就能和它一起移动了 And it’s the same with a unicycle.而独轮车也是这个原理 In order to go forward, first, you have to pedal back.要想向前骑 首先你得往后踩踏板 So, you’re leaning forward这样 你就在向前倾了 and then you can go forward with it.然后你就可以骑着独轮车前进了 “Everything you’re doing on a unicycle“你所做的一切 is all about keeping that contact patch都是为了把车轮与地面的接触点 right where it needs to be relative to you.保持在相对于你来说 正确的位置上 You’re balancing the broomstick. It’s just that on a unicycle,就像保持扫帚平衡 骑独轮车时也是一样的道理 you do the longitudinal balance with the pedals你踩踏板保持纵向平衡 and you do the lateral balance, the side-to-side,同时保持左右横向平衡 the same as you do with a bike.与骑自行车同理 You essentially sorta small counter-steer to get that weight,主要是稍往反方向移动 施加重力 to get the contact patch out,使接触点移动过去 and then you can pedal and bring it under you.”再通过踩踏板把它调整到正确位置” Now I should point out that现在 我要说的是 sometimes when the steering locked,车的转向锁定时 we just happened to be leaning in the right direction有时我们只是恰好往正确方向倾斜了 to execute the turn.从而实现了转向 “Right, right, right, right, right, right.”“右转 右转 右转 右转 右转 右转” [Off Screen]”Oh, managed it!”[画外音]“噢 成功了!” Essentially by sheer luck,我们基本纯靠运气 we had counter-steered before that side of the handlebars locked out.趁着车把锁上之前 反方向转了一下 “Now, I can…I can keep going.”“现在 我可以……一直骑下去了” – Yeah, but don’t turn left or you’re gonna be screwed. – Don’t turn left.– 对 但别左转 不然你就完蛋了 – 别左转 I can’t turn left.我不能左转 “What’s interesting about this is it shows“有意思的是 这说明 that you can still ride the bike perfectly well, right?我还是可以骑得很好的 对吧? It’s just you can’t turn left.”只是你不能左转而已” – The funny thing is that you couldn’t initiate the turn. – Right.– 自己不能拐弯儿 太可笑了 – 是啊 “I mean, the wild takeaway is that“我们得出了一个很棒的结论: steering is not just for turning the bike;转向不只是为了让自行车转弯 steering is for balancing.”还是为了保持平衡” “That’s exactly right.”“完全正解” Why is it hard to balance on a stationary bike?为什么很难让静止的自行车保持平衡呢? I think most people believe我想多数人认为 it’s because the wheels aren’t spinning是因为车轮不转 so there’s no gyroscopic effect,所以就不会产生陀螺效应 but that’s not it.但事实并非如此 The truth is you use steering事实是你得通过转向 to keep the bike underneath you让自行车保持在身体正下方 but steering doesn’t work when you’re stationary.但当你不动时 转向是不起作用的 Your balance comes not so much你的平衡并不取决于 from how you position your body over the bike,你在自行车上的位置 but by how you steer the bike to keep it underneath you.而取决于如何控制自行车处在身体正下方 Even when going straight,即便直行时 you’re constantly making small steering adjustments to maintain balance.你也要不断微调转向 来保持平衡 “You’re moving the contact patch of the front wheel under you.“其实你在移动位于你下方的 前轮接触点 You’re doing exactly what you do when you balance a broomstick on your hand.”就像平衡手上扫帚时所做的一样” So, if the rider is responsible for steering the bike to keep it balanced,那么 如果骑手负责让自行车转向 从而保持平衡 how do bikes without riders stay upright?那么没人骑的自行车 又如何保持直立呢? As long as a bike is moving with sufficient speed,自行车只要以足够快的速度移动 it can keep coasting indefinitely.就能不断滑行 I first became aware of this phenomenon我最初是通过《一分钟物理》 through the great videos by MinutePhysics,一些精彩的视频知道这一现象的 which inspired me to make this video.是它们启发我制作了这个视频 You should definitely check them out.你们一定要去看看 But it turned out the ground而事实证明 虽然我们测试时 where we went to test this effect was really bumpy,行经的路面非常颠簸 but the bike still manages to absorb all these perturbations但自行车仍能应对自如 and remain stable.并且保持稳定 So, how does it do this?这又是如何实现的呢? I think most people believe it’s the wheels spinning我想多数人会认为是车轮转动 that creates some sort of gyroscopic effect that resists falling over.产生了某种陀螺效应 从而避免了摔倒 Just like in this demonstration of gyroscopic precession.就像在这里演示的陀螺进动一样 The wheel stays upright even though gravity is pulling it down尽管重力将车轮往下拉 车轮还是能保持直立状态 But this is not why bikes are stable.不过这并非自行车能保持稳定的原因 Just watch what happens when we lock the handlebars completely.看看我们将车把完全锁住时 会发生什么 So you can only go straight ahead.看来你只能向前直行 “Locked out, locked out. Whoa!”“锁住了 锁住了 呜喔!” “All that is happening is the steering is locked.“现在的情况是 转向锁住了 You just got to ride it. You don’t have to turn.”你得骑下去 不要转弯” – You just ride. – Go straight. – 你骑就行 – 直行 “Letting go.” Some people tried going really fast.“尽管骑吧” 有些人试图骑得很快 [group laughs][人群大笑] “Holy crap! This is impossible.”妈呀!没戏的 Others experimented with extreme balancing techniques.其他人则尝试用极好的平衡技巧来骑 – He’s leaning. Leaning hard. – Don’t go too fast.– 他斜了 斜得很厉害 – 别骑太快 [group laughs][人群大笑] But even with the gyroscopic effect of the wheels,不过 尽管有车轮的陀螺效应 no one was able to keep the bike upright for more than a few seconds.也没人能让自行车直立超过几秒钟 [crowd exclaims]”Wow!”[人群欢呼]“哇哦!” “This is not safe for a second.”“太要命了这车” It is just as hard to balance on a bike with locked steering在锁定转向的自行车上保持平衡 as it is to balance on a stationary bike.和在静止车上一样困难 “No, this one is impossible.”“不可能不倒呀” Because you can’t steer the bike back under you.因为你无法控制自行车回到身体正下方 The real reason bicycles are stable without riders没人骑的自行车能保持稳定的真正原因 is because they’re cleverly designed to steer themselves.是因为它们能自动转向的巧妙设计 If they start falling to one side,如果它们开始倒向一边 the handlebars turn in that direction车把就会朝那个方向转 to steer the wheels back underneath them.来控制车轮回到车把正下方 At least three mechanisms are responsible for a bike’s corrective steering.至少有三种机制 与自行车自动纠正转向有关 The first is that due to the angle of the front fork,首先 由于前叉的角度 the steering axis intersects the ground转向轴在车轮与地面接触点的前方 in front of where the wheel touches the ground.与地面相交 So, if the bike starts leaning to the left,所以 如果自行车开始向左倾斜 the force from the ground on the tire turns the wheel to the left.地面对轮胎的作用力 就会使车轮转向左边 If the bike starts leaning right,如果自行车开始向右倾斜 the force from the ground pushes the wheel to the right.来自地面的力就会把车轮推向右边 The front wheel of a bicycle is essentially a caster wheel,本质上 自行车的前轮就是个脚轮 like those you find on strollers or shopping carts.就像我们婴儿车或购物车上的脚轮 Whichever way you drive them,无论你朝哪个方向推车 the wheel falls in line and rolls in the same direction.轮子都会成直线 并朝同一方向滚动 The second reason for a bike’s corrective steering is that自行车能自动纠正转向的第二个原因是 the center of mass of the handlebars and front wheel车把和前轮的质心 are located slightly in front of the steering axis.略位于转向轴的前方 So, when the bike leans left,所以 自行车向左倾斜时 their weight pushes the front wheel to the left.其重量会把前轮推到左边 If the bike leans right, their weight steers to the right.如果自行车向右倾斜 其重量就使车右转 And the third mechanism is a gyroscopic effect,第三种机制确实是陀螺效应 but it doesn’t keep the bike upright directly; it just helps steer.但它不能直接让自行车直立 只能辅助转向 If you have a gyroscope and you push down on the left-hand side,如果你有个陀螺 把左手边向下推 the gyro will turn left.陀螺就会左转 If you push down on the right side, it will turn right.如果把右边向下推 陀螺就会右转 This is known as gyroscopic precession.这就是所谓的陀螺进动 It seems as though the force you apply我们施加的力 takes effect 90 degrees from where you applied it.似乎在施力点90度处起了作用 So, bikes are stable primarily because of steering.所以 自行车稳定主要是靠转向 They have built-in mechanisms for steering themselves.它们有内置的机制来实现自动转向 In fact, you don’t need all three mechanisms to create a stable bike.事实上 无需兼具三种机制 才能保证其稳定 Researchers created this weird-looking bicycle to prove a point.研究人员发明了这辆外形怪异的自行车 来证明这一观点 It has no gyroscopic effect由于接触地面的轮子上方 thanks to counter-rotating wheels above the wheels that touch the floor.有反向旋转的轮子 所以这辆车没有陀螺效应 Plus, there is no caster effect而且 因为前轮在转向轴前方 because the front wheel touches the floor in front of the steering axis.先接触地面 所以也不存在脚轮效应 But this bike is made stable by its mass distribution,其实 这辆车是靠其质量分布来保持稳定的 the force of gravity on which steers it in the direction of any lean.重力使它转向任意倾斜的方向 Understanding how bicycles work is still an active area of research.理解自行车的工作原理 仍是个活跃的研究领域 There is a program you can use to input all the different bicycle parameters这里有个程序 你可以输入所有不同的自行车参数 and see the range of speeds over which it is self-stable.并查看保持自行车自身稳定的速度范围 And this research is leading to better bikes.这项研究将创造出更好的自行车 This prototype has a smart motor in the handlebars这款原型车的车把上有个智能马达 to actively help steer, keeping the bike upright even at low speeds.可以辅助转向 即使自行车低速行驶时也能使其保持直立 I guess it’s fitting that we are still learning new things about bicycles我觉得 大家仍在学习自行车相关的新知识非常不错 since most of us are able to ride one因为我们大多数人都会骑车 without any knowledge of how we’re actually doing it.却不了解实际原理 [futuristic sound effects play][科幻音效] Hey, this video is sponsored by KiwiCo,嘿 本视频由KiwiCo赞助 creator of awesome hands-on projects and toys它创造了很棒的实践研究项目和玩具 designed to expose kids to STEAM concepts.旨在让孩子们接触STEAM概念 And with the holidays fast approaching,随着假期临近 a KiwiCo subscription is the perfect gift对你身边任何一个年轻人而言 for any of the young people in your life.订购KiwiCo都是一份完美的礼物 KiwiCo now has nine different subscription lines现在KiwiCo针对不同年龄层和主题 for different age groups and topics.有九种不同的订购渠道 Plus, they ship to more than 40 countries.而且 产品销往40多个国家 I think it’s such a great gift我觉得这真是份很棒的礼物 because each month a box turns up at your door因为每个月都有个盒子出现在你家门口 and provides hours of entertainment and learning.供你娱乐和学习几小时 My kids love building KiwiCo projects with me.我娃很喜欢和我一起搭建KiwiCo项目 It’s a special thing we do together我们一起动手制作 这很特别 and you can jump right in你可以马上加入进来 because each box comes with all the supplies you need,因为每个盒子里都有你需要的全部东西 even a few extra in case you lose something.甚至还有一些备份 以防你弄丢东西 You know, today I built this waterwheel fountain今天我搭了这个水车喷泉 in fitting with the wheel theme.来搭配车轮主题 The design and instructions are so well thought out设计和说明书都是如此的精细周到 because each project is designed by experts因为每个项目都是由专家设计的 and tested with kids.并在孩子中测试过 There’s also an educational magazine还有一本教育杂志 with lots of additional content around the crate’s theme.里面有许多与盒中主题相关的附加内容 For viewers of this channel,对于本栏目的观众 KiwiCo are offering 50% off your first month of any crate.KiwiCo将会给您首月订购打五折 Just go to kiwico.com/veritasium50.只要进入kiwico.com/veritasium50即可下单 I will put that link down in the description.我会把链接放在产品描述里 So, I want to thank KiwiCo for supporting Veritasium我想感谢KiwiCo对《真理元素》栏目的支持 and I want to thank you for watching.也感谢您的收看
  • 2022-06-27世界上最成功的科学理论:标准模型400 years ago,四百年前 Galileo started piecing together the basic principles of reality—伽利略开始厘清现实世界的基本原则 what we now call modern science.即我们今天所说的现代科学 But the questions he was trying to answer are as old as humanity itself.但他设法回答的这些问题 古老如人类本身: What are we made of?我们是由什么组成的? What are the fundamental building blocks of the universe构成了你 我 星辰 以及世间万物的 from which you, me, the stars, and everything else is constructed?宇宙基本组成部分是什么? In the centuries since Galileo,自伽利略之后的几个世纪 thousands of theories and experiments have peered into smaller and smaller distances…成千上万的理论和实验研究着越来越小的物质单位 converging on a single picture of the structure of matter.最终汇成物质结构的单一图像 This somewhat daunting-looking formula is where we end up.这个令人有些望而却步的公式 就是我们得出的结论 It gives the correct answer to hundreds of thousands of experiments,它为成千上万的实验提供了正确的答案 in some cases with an accuracy that is unprecedented in science.在某些情况下 其准确性甚至在科学界都是前所未有的 It is, by any measure,无论用何种方式衡量 the most successful scientific theory of all time.它都是有史以来最成功的科学理论 And yet for something so extraordinary,但是 对于如此非凡的理论 we give it a rubbish name.我们却给它起了一个蹩脚的名字 We call it the Standard Model.我们称之为标准模型 I’m David Tong, a theoretical physicist at the University of Cambridge.我是David Tong 剑桥大学的一名理论物理学家 And in this video, we’re going to build the Standard Model, piece by piece.在这个视频中 我会带你们一步一步地建立标准模型 I hope that, by the end,我希望 到视频最后 you’ll have some intuition for how all of the parts fit together你们多少能感受到 所有的物质是如何组合起来 to create the fundamental building blocks of our universe.从而创造出我们这个宇宙的基本构件的 This is the Standard Model.这就是标准模型 It describes how everything in the universe它描述了宇宙中的一切 is made of 12 different types of matter particles,如何由十二种不同类型的物质颗粒组成 interacting with 3 forces,与3种力互相作用 all bound together by a rather special particle 最后被一种非常特殊的希格斯玻色子颗粒 called the Higgsboson.束缚在一起 Before we get going, some caveats.在我们开始之前 有几件事要提醒大家 First…I said “three forces”.首先 我刚刚说了“三种力” While there are actually four fundamental forces at play in the universe.但其实宇宙中有四种基本的作用力 This means that there’s something missing from this picture.这意味着这张图中少了什么东西 And that something would be gravity,而这个缺少的东西就是引力 the most obvious force at play in the world around us and yet,它是我们身处的世界中最明显的力 in many senses, the one we understand least.但从很多方面来说 也是我们最不理解的一个力 We do have a theory of gravity, a very successful theory.我们的确有关于引力的理论 而且这一理论非常成功 It was given to us by Albert Einstein and goes by the name of general relativity.它由阿尔伯特·爱因斯坦提出 被称为广义相对论 But there are two good reasons why it’s not included in the Standard Model.但为什么标准模型并不涵盖它 这里有两大原因 The first is that, at the microscopic level,第一 在微观层面上 the force of gravity is so weak引力太过微弱 that it barely has any effect on a single subatomic particle.以至于它对单个亚原子粒子几乎没有任何作用 The second is that we don’t really know how to incorporate general relativity,第二 我们其实并不知道如何把广义相对论 which is a classical theory, into the quantum world.这种经典理论 糅合到量子世界中 We have no idea how to peer into a black hole我们不知道如何窥视黑洞 where quantum gravity effects are clearly at work.量子引力效应显然在那里起作用 A second caveat第二点要注意的是 is that the Standard Model is written in a language known as quantum field theory.标准模型是由一种被称为量子场论的语言写就的 This tells us that matter, at the fundamental level,这意味着 物质在基本层面上 is not really made up of particles.并不真正是由粒子构成的 Instead, it’s made up of fields:相反 物质是由场构成的: fluid-like objects which are spread throughout all of space.场是流体一般的物质 遍布整个空间 These fields are engaged in an intricate, harmonious dance to a music这些场伴随着我们称之为物理定律的音乐 that we call the laws of physics.跳着复杂而和谐的舞蹈 The interactions between the fields produce the physical world in the form of particles.场之间的相互作用以粒子形式创造了物质世界 To understand the Standard Model,要理解标准模型 it’s more convenient to use the language of particles.用粒子的语言来说明会更为便利 As we build up the Standard Model,我们在建立标准模型的过程中 we’re going to meet lots of particles with an array of names将会遇到许多粒子 它们的名字也千奇百怪 that can very quickly become bewildering.很快就会让人眼花缭乱 But there is one classification that is, by far, the most important:但有一种类别是迄今为止最重要的: Every particle is either a fermion, which is a matter particle,每一个粒子要么是费米子 一种物质粒子 or a boson, which is a force particle.要么是玻色子 一种作用力粒子 The distinction between fermions and bosons lies in the quantum world.费米子和玻色子的区别在于 量子世界中 Fermions must obey something that we called the Pauli exclusion principle.费米子必须遵守我们所说的泡利不相容原理 Roughly speaking,大致来说 this means that you can’t put two fermions on top of each other in space.就是你不能让两个费米子挤在一个空间 As such, these are the building blocks of matter.它们本身 就是物质的基石 Bosons, on the other hand,另一方面 玻色子 can pile on top of each other as much as they want可以随心所欲的占据同一个空间 because they’re not obliged to obey the Pauli Exclusion principle.因为它们不必遵守泡利不相容原理 Bosons are the particles that mediate various forces玻色子是传递各种作用力的粒子 and we’ll talk about them more later.我们之后会详述 For now, let’s start by looking at the fermions.现在 我们先来看看费米子 Everything that we’re made of can be reduced to just three matter particles:构成我们的一切事物都能被简化为三种物质粒子: this is the electron and two species of quarks that we call the up quark and the down quark电子和两种夸克——上夸克和下夸克 The familiar proton and neutron each contain three quarks.我们熟悉的质子和中子各包含三个夸克 The proton has two up quarks and a down,质子有两个上夸克和一个下夸克 while the neutron has two down quarks and an up.而中子有两个下夸克和一个上夸克 Put protons and neutrons together, and you have a nucleus.把质子和中子放在一起 就得到了原子核 Add electrons into the mix and you have an atom.再把电子加入其中 就得到了一个原子 Put a bunch of atoms together and that’s what we’re made of.把一堆原子放一起 这就构成了我们 All the beauty and complexity that we see in the world around us我们在世界上所看到的一切美丽与复杂的事物 can be traced to this same collection of three particles,都能溯源到同样是这三种粒子构成的集合 rearranged over and over in different combinations.只不过一次次组合的形式不同而已 Next comes the fourth type of matter particle.接下来是第四种物质粒子 It’s called the neutrino and it’s not like the others.它叫作中微子 而且跟其他粒子不同 Neutrinos are extremely light and barely interact with anything else.中微子重量极轻 而且几乎不与其他粒子相互作用 For example, in the time it took me to say that,例如 在我说出这句话的时间里 something like 100 trillion neutrinos passed through your body.有大约100万亿的中微子穿过了你的身体 Most of them came from the sun,其中大多数来自太阳 but millions of them have been streaming uninterrupted through the universe但有数百万是从宇宙大爆炸后的几秒钟起 since the first few seconds after the Big Bang.就在宇宙中不断地流动 So, there we have it: four matter particles.现在 我们认识了四种物质粒子 Three that make up you, me, and everyone we know,其中三种构成了你 我和所有其他人 and one very peculiar cosmic ghost flowing through us all.还有一种就如奇异的宇宙幽灵在我们之中流动 But here’s where things start to get weird.但是 事情开始变得古怪了 Because Nature didn’t stop there.因为自然并没有止步于此 For reasons that we don’t understand,出于某种我们无法理解的原因 she took this collection of four particles她创造了这四种粒子 and made two further copies.然后又制造了两份副本 This means that there are actually three different kinds of electron-like particles.这意味着实际上有三种不同的类电子粒子 In addition to the original electron that we know and love,除了我们所了解和喜爱的原始电子 there are particles called the muon and the tau.还有两种叫做μ子和τ中微子 The muon and the tau behave exactly like an electron,μ子和τ中微子的行为极像电子 with one important exception:但有一个重要区别: they’re heavier.它们质量更大 The muon is about 200 times heavier than the electron,μ子的质量是电子的200倍 the tau almost three and a half thousand times heavier.τ中微子的质量是电子的3500倍 The same generational pattern then repeats for the quarks.同样的代际模式也出现在夸克之中 There are two heavier versions of the down quark,有两种质量更大的下夸克 that we call the strange, and bottom quarks我们称之为奇异夸克和底夸克 and two heavier versions of the up quark called charm and top还有两种质量更大的上夸克 称为魅力夸克和顶夸克 And then there are also two more neutrinos:另外 还有两种中微子: we become a little bit unimaginative in our naming我们的命名有点缺乏想象力 and call the full collection the electron neutrino, the muon neutrino, and the tau neutrino.这整个集合中有电子中微子 μ子中微子和τ中微子 Now, we don’t see the second and the third generations of particles in everyday life.现在 我们在日常生活中看不到第二代和第三代粒子 We can create these heavier particles我们可以制造这些质量更大的粒子 but they are unstable,但是它们不太稳定 which means that they quickly decay to the first generation of particles that we’re made of.这意味着它们会很快衰变为构成我们的第一代粒子: Nonetheless, we know they exist.虽然如此 我们知道它们是存在的 We can detect them in particle accelerators.我们可以在粒子加速器中探测到它们 In some cases, we’ve even been able to take photographs of the tracks they leave behind.某些情况下 我们甚至能拍下它们留下的痕迹 This is the collection of particles that makes up our world.这就是构成我们世界的粒子集合 Three sets of four.三组集合 每组四种物质粒子 Now some of this we understand very well.其中一些 我们非常了解 In particular, we understand why particles have to come in a set of four.特别是 我们理解为什么粒子必须以四个一组的形式出现 There is a mathematical consistency condition in the Standard Model标准模型中有一个数学一致性条件 that tells us that you can’t have one particle without the other three.它告诉我们 没有其他三种粒子时 粒子不能单独存在 In contrast相对而言 we don’t understand at all why there are three generations rather than any other number.我们完全不懂 为什么有三代 而不是其他数字 That remains a complete mystery.这仍然是个未解之谜 There is, however, a surprising aspect of mathematical unity here:然而 数学统一性令人惊讶的一个方面是 all particles are described by exactly the same equation.所有的粒子都由完全相同的方程描述 This equation was written down in the 1920s by the physicist Paul Dirac20世纪20年代 物理学家保罗·狄拉克写下了这一等式 originally to describe the electron.最初 它是用来描述电子的 But, as we discovered more and more particles (quarks and neutrinos)但是 随着我们发现了越来越多的粒子(夸克和中微子) we realized the Dirac equation or variants of it.我们认识到 狄拉克的等式或它的变体 also describles them.同样适用于它们 So, that’s the stuff we’re made of.这就是组成我们的基本物质 But still we’re missing something crucial!但我们仍然漏了一些重要的东西! We are missing the forces.我们遗漏了“力” Without the forces, the universe would be boring.没有这些力 宇宙将会变得无趣 All of the particles would wander around the cosmos like lost souls,所有粒子都会像迷失的灵魂一样在宇宙游荡 never interacting, never doing anything interesting.不会相互作用 也不会发生任何有趣的事 There are three fundamental forces in the Standard Model标准模型中有三种基本力 the electromagnetism,电磁力 the strong force,强力 and the weak force.和弱力 Each of these forces comes with an associated particle.每一种力都伴随着一个相关的粒子 These particles are what we called bosons,这些粒子就是我们所说的玻色子 the other half of our particle family.我们粒子家族的另一半 Bosons are force-carrying particles.玻色子是携带力的粒子 In one way of viewing things,从一个角度来看 you can think of the fermions as constantly swapping bosons between them你可以理解为费米子在不停地交换玻色子 affecting their motion影响它们的运动 and giving rise to what we call a force.并产生我们所说的力 Let’s begin with the most familiar of these forces.让我们从最熟悉的力开始 Electromagnetism is responsible for the chemical properties of the elements电磁力决定了元素的化学性质 and we’ve harnessed it to create much of modern technology.我们利用它创造了许多现代科技 It acts on anything that carries electric charge.它对任何带电荷的东西都起作用 That means that it acts on the electron-type particles and the quarks,这意味着它作用于电子型粒子和夸克 but not on the neutrinos但对中微子没有影响 because neutrinos are electrically neutral.因为中微子是电中性的 An electron sitting in space will give rise to an electric field位于空间中的电子会产生一个电场 which spreads radially outwards,呈辐射状扩散 and attracts or repels all other electrically charged particle in its neighborhood.并吸引或排斥其附近所有其他带电粒子 But if you look more closely at that electric field,但是如果你仔细观察那个电场 you will find that it’s comprised of the particles of electromagnetism你会发现它是由电磁粒子组成的 These particles we call photons.这些粒子我们称之为光子 Next is the strongest fundamental force in nature,接下来是自然界中最强的基本力 aptly named the strong force.它被恰当地命名为强力 This force acts only on quarks and, subsequently, on particles like protons and neutrons that这种力只作用于夸克 随之作用于质子和中子 are made of quarks.这些由夸克组成的粒子 it is the strong force that holds together the nuclei of atoms.正是强力 使得原子核结合在一起 It’s also this force that is responsible for nuclear fission也正是这种力量导致了核裂变 and gives the energy that is released in an atomic explosion.并产生了原子爆炸释放的能量 Just as the photon is associated to electromagnetism,正如光子与电磁力联系在一起一样 there is a particle associated to the strong force.也有这样一个粒子与强力有关 We call it the gluon because it literally sticks quarks together.我们称之为胶子 因为实际上是它将夸克粘在一起 As the electron gives rise to an electric field,正如电子会产生电磁场一样 so a quark sitting in space will give rise to a gluon field.空间中的夸克也会产生一个胶子场 But now something different happens:但是这回发生的事有些不同: unlike electromagnetism, the field doesn’t spread out radially.与电磁学不同 胶子场不会呈放射状扩散 Instead, the quark produces a thin flux tube,相反 夸克产生了一个薄通量管 a string-like object, which can only end when it finds a different kind of quark.类似于弦 只有遇到不同种类的夸克时才会停下来 This is what makes the strong force strong.这就是强力之所以强的原因 Because the quarks are joined by a flux tube,因为夸克是由通量管连接在一起的 it takes more and more energy to pull them apart.要把它们拉开就需要更多的能量 This is why we never see quarks on their own.这就是我们看不到单独的夸克的原因 They’re always bound together by the strong force inside bigger particles,它们总是被较大粒子内部的强力束缚在一 like protons and neutrons.例如质子和中子 The third and final force is the most intricate and subtle of them all.第三种也是最后一种力是所有力中最复杂和最微妙的 This is the weak force.这就是弱力 Like the strong force, the weak force acts only on subatomic distances.像强力一样 弱力只作用在亚原子的距离上 But rather than bind particles together, the weak force is all about decay.但是弱力不是将粒子结合在一起 而是衰变 We just learned that the strong force binds quarks together to form protons and neutrons,我们刚刚了解到强力将夸克结合在一起形成质子和中子 creating the atomic nucleus.创造了原子核 The weak force has the astonishing ability to allow quarks to switch their identity.弱力的惊人力量可以使夸克转换身份 A down quark can turn into a up quark,一个下夸克可以变成上夸克 releasing an electron and neutrinoin the process.在这个过程中释放出一个电子和中微子 This means that a neutron can morph into a proton.这意味着一个中子可以变成一个质子 What we call radioactive beta decay.我们称之为放射性β衰变 In this way, the weak force is responsible for the nuclear fusion reactions这样的话 弱力负责核聚变反应 that power the sun and produce the energy required for life on Earth.为太阳提供动力 并产生地球生命所需的能量 Finally, the weak force is also the reason that heavier matter particles最后 弱力也是较重物质粒子 quickly decay into the three lighter and more stable fermions迅速衰变为三个更轻更稳定的费米子的原因 that make up matter we know it.这三种费米子构成了我们所知道的物质 There are particles associated to the weak force也有与弱力相关联的粒子 we call these the W and Z bosons.我们称之为W玻色子和Z玻色子 The weak force is the only one of the three forces to act on all the particles. 弱力是三种力中唯一作用于所有粒子的力 In particular, it’s the only force that neutrinos feel.特别的是 它是唯一能作用于中微子的力 Finally It’s time to meet the last piece of the jigsaw:终于到了拼图的最后一块了: the particle that in many ways ties the whole Standard Model together.从多个方面将整个标准模型联系在一起的粒子 This is the Higgs boson.那就是希格斯玻色子 To explain why the Higgs boson is so special, 为了解释希格斯玻色子的特殊之处 I should first tell you a striking fact:我要先告诉你一个惊人的事实: none of the fundamental particles in the world have a mass.世界上的基本粒子都没有质量 This is where the Higgs boson comes in.这就是希格斯玻色子的用武之地 Its role is to endows all fermions with a mass. 它的作用就是赋予所有费米子质量 I’d love to be able to give you a clear explanation of why this happens.我很想给你们解释清楚 为什么会发生这种情况 But sadly it’s difficult to come up with good analogies for the Higgs field.但遗憾的是 要给希格斯场找到好的类比真是太难了 Here is what I would say as a so-so analogy所以我只能讲一个一般的类比 you should view the Higgs field as something like a cosmic molasses,你应该把希格斯场看作类似宇宙糖浆的东西 speard through out the universe弥漫在整个宇宙中 trapping matter particles as they travel through space在物质粒子穿越空间时捕获它们 and giving them what appears to us, to be a mass并赋予它们我们都拥有的东西 那就是质量 So this is the Standard Model:这是标准模型: 12 matter particles, interacting with 3 forces and a Higgs field.12种物质粒子与3种力和一个希格斯场相互作用 It’s a beautiful picture, the pinnacle of 400 years of science.这是一幅美丽的图画 是400年来科学的顶峰 But it’s clear that the Standard Model is not the last word in physics.但是很明显 标准模型并不是物理学的最终结论 Since the discovery of the Higgs boson,自从发现希格斯玻色子以来 physicists like me feel that in many ways像我这样的物理学家都觉得在很多方面 the Standard Model is too successful.标准模型都过于成功了 It gives the right answer to every experiment that we can do.我们做的每个实验 它都给出了正确答案 Our current hope is that we will eventually find an experiment 我们当下的愿望是 最终做出一个 that it gives the wrong answer to.标准模型无法给出正确答案的试验 And there are some hints that this is happening.有一些迹象表明这一切正在实现 Because only then can we get clues about what lies beyond.因为只有这样我们才能得到关于更多未知领域的线索 One of the open questions about the Standard Model关于这个模型的一个悬而未决的问题是 is whether the three fundamental forces are actually different这三种基本力量是否是本质不同的 or whether they are a manifestation of a single all-encompassing force.或者 是否存在一种包罗万象的力 可以囊括这三者 This is the dream of a Grand Unified Theory.这就是大统一理论的理想情况 There are some theoretical signs that this may be the way things work out某些理论表明 事情可能就是这样的 but so far no experimental confirmation.但到目前为止还没有实验可以证实 Of course, we’re also left with the obvious thing that’s missing:当然 我们还缺了一个显而易见的东西 that’s gravity那就是引力 At the beginning of the video, I talked about the problem of quantum gravity.视频一开始 我就谈到了量子引力的问题 In recent years we’ve discovered gravitational waves近些年 我们发现了引力波 which are ripples of space and time itself.它是空间和时间本身的涟漪 And, if we look closely,如果我们仔细观察 there are good reasons to believe that these waves are made of quantum particles就有足够的理由相信 这些波是由量子粒子组成的 that we call gravitons我们称之为引力子 just like light waves are made out of photons.就像光波是由光子组成的一样 There are other things missing too.缺漏的地方还有一处: the Standard Model doesn’t include the invisible realm of dark matter and dark energy标准模型不包括暗物质和暗能量这些不可见领域 which means that we’re missing an explanation这意味着我们对宇宙中 for a whopping 95% of the energy in the universe.高达95%的能量的无法给出解释 Dark matter is almost certainly made up of additional particles几乎可以肯定 暗物质由别的粒子组成 that don’t interact with electromagnetism.它们不与电磁相互作用 Perhaps these particles have their own forces and their own messenger bosons.也许这些粒子有自己的力和自己的信使玻色子 And there are still more questions about the Standard Model关于标准模型还有很多问题 that we just don’t know how to answer.我们尚不知如何解答 Why is the muon 200 times heavier than the electron,为什么μ子质量是电子的200倍 while the top quark is almost 350,000 times heavier than the electron?而顶夸克的质量几乎是电子的35万倍? Why are the neutrinos a million times lighter?为什么中微子要轻一百万倍? We have no idea.我们完全不知道 We have no way of predicting the masses of these particles我们没有办法预测这些粒子的质量 other than going out and measuring them in experiments.除非我们在实验中去测量 But there are clearly patterns within these masses of particles但是显然 这些大量的粒子存在某种模式 which strongly suggest that there is some underlying structure just waiting to be uncovered.这是存在潜在结构的有力信号 有待进一步揭示 The hope is, with experimental results going hand in hand with new theoretical ideas我希望随着实验结果与新的理论观点携手并进 we will ultimately be able to reveal the next layer of reality我们最终将能够揭示下一层现实的面纱 and understand what lies beyond the Standard Model.理解标准模型之外更多的世界 Until then, we continue Galileo’s journey,在那之前 我们会继续伽利略的旅程 with the ultimate goal致力于他的终极目标: a theoretical framework to explain the universe and everything in it.一个能够解释宇宙万物的理论框架 a theory of everything.一个万物理论
  • 2022-06-27修条环球公路可好?[ MUSIC PLAYING ][音乐播放中] It’s AumSum Time.欢迎来到《奥萨小课堂》 如果我们围绕世界修一条路会怎样? Then I will name it the AumSum Highway.那我将把它命名为“奥萨高速公路” Wow , AumSum.真棒 Aumsum Firstly, you will definitely find its name首先 你肯定会在《吉尼斯世界纪录》里 in The Guinness Book of World Records.找到它的名字 Secondly, if it had a dedicated bike lane.其次 如果它有专用的自行车道 The entire world will get fitter, much faster.整个世界将变得更美好 更快捷 Thirdly, it sounds like a good idea.第三 这听起来是个好主意 But would prove to be extremely difficult to execute from但由于地形 经济及政治因素 Geographical, financial as well as political point of view.修条环球高速将极其困难 Fourthly , global trade will probably get a major boost.第四 全球贸易可能会大幅提升 It will also prove to be a major engine of worldwide job-creation.这也证明了它是全球创造就业的主要引擎 Fifthly, car companies would be one happy lot.第五 汽车制造商们将会很高兴 While airplane manufacturers might not be too excited about it.但飞机制造商们可能就不太开心了 Lastly, if all the countries were to agree on this,最后 如果全世界能达成一致 then it would prove to be那证实它将是 one of the biggest show of solidarity by humanity.人类团结的最大表现之一 要是轮子从未被发明会怎样? No problem.那没什么 I’ll just use my private rocket.我就开着自己的私人火箭好了 Oh… AumSum.啊…… AumSum Wheels are believed to have been invented almost 5,500 years ago.据说轮子是在大约5500年前被发明的 Ever imagined what the world would be like without wheels ?你可曾想过没有轮子的世界是什么样子? How would you go to school , work or even holiday?你们将如何上学 工作 甚至度假? 若自行车 汽车 蒸汽机 甚至飞机 没有轮子的话 它们将都不会存在 Yes. Horses and sledges will be there,是的 虽然有马和雪橇 but it would be a super slow and super rough ride.但却非常缓慢 非常颠簸 不仅在运输领域 就是工业革命中 轮子也是一个重要组成部分 Elevators, blinds, cranes, etc,比如电梯 百叶窗 起重机等 all have some form of wheels hidden in them .它们构造中都有各种形式的轮子 on adding teeth to wheels,gears were invented给轮子增加齿 于是就发明了齿轮 clocks, blenders, car engines, bicycles时钟 搅拌机 汽车引擎 自行车 and other complicated machines all work with the help of gears.及其他复杂的机器 都是借助齿轮来工作 So basically,所以 总的来说 如果从来没有发明轮子 我们可能仍过着史前生活 要是我们耗尽所有化石燃料会怎样? Then I will eat all the burges in the world.那我就吃掉世界上所有的汉堡 Oh… AumSum.啊…… AumSum Fossil fuels and natural fuels化石燃料和天然燃料 such as coal,oil or natural gas, 比如 煤 石油 天然气 which is formed over millions of years.是由死去的生物的厌氧分解 from the anaerobic decomposition of dead organisms.经过数百万年形成的 Now, if we were burning of the fossil fuels in the world,现在 如果我们在世界上燃烧化石燃料 then more than 5 trillion tons of greenhouse gases mostly carbon dioxide那么 会有超过五万亿吨主要是二氧化碳的温室气体 will be released in the atmosphere.被排放到大气中 这会导致我们超过四亿年看不见温室标高 As a result,最终 global temperature will increase by more than 10 degrees celsius.全球温度将升高10℃以上 All the ice on earth would melt地球上所有的冰将融化 increasing sea levels by more than 100 feet海平面上升100多英尺 plus submerging all the costal cities of the world.淹没世界上所有的沿海城市 lastly , rainfall would be highly unpredictable.最后一点 我们将很难预测降雨 Some areas will receive the extreme rainfall,一些地区会迎来强降雨 while others would receive very less.而另一些地区雨量却很少 What if we will plant a trillion trees?要是我们种一万亿棵树会怎样? I will eat up billion burgers.那我就吃掉十亿个汉堡包 Oh… AumSum.啊…… AumSum There are about three trillion trees on earth right now. 现在地球上大约有三万亿棵树 So planting a trillion trees would increase that number by 33%.所以种一万亿棵树就会增加33% The impact will definitely be positive它对我们以及所有生物的影响 for us as well as all the living things.肯定是积极的 但这不会马上解决气候变化问题 Firstly,we bring up so much land for planting trees.首先 我们划出这么多的土地用于种树 Seems like a mammoth task.这似乎是一项很艰巨的任务 Secondly , these trees will take a number of years to grow big enough其次 这些树要过几年才能长大 to make any meaning for contribution到那时才能发挥作用 towards reducing carbon dioxide from air.降低空气中二氧化碳的浓度 Thirdly , if we do nothing about emissions第三 如果我们对排放什么都不做 and even adding carbon dioxide to the atmosphere.甚至向大气中释放更多二氧化碳 Then, by the time trees grow,那 等到树长大之时 we would have added more than one trillion tons of carbon dioxide.我们会增加一万亿吨以上的二氧化碳 Does not find the effects of these trees?没发现这些树的作用吗? So plantation of trees plus cutting emissions那就栽树的同时减少碳排放 or the need of the year.或降低全年需要 Hmmmm hmmmm Hurrah !嗯嗯 啊哈哈哈 What plastic was never invented ?什么塑料从未被发明过呢? No problem.不用着急 Instead of plastic, people all use on mastic.人们都用乳香代替塑料 Stop it , AumSum.停! AumSum Plastic is not biodegradable与有机废料相比 as compared to organic waste.塑料不能被生物降解 It takes hundreds of years to decompose.分解它需要几百年的时间 没有塑料意味着 土地和水污染将大大减少 But , plastic is cheap,但是 塑料很便宜 extremely easy to manufacture,very versatile and doesn’t get affected by water.它极易制造 通用性强且不受水的影响 It would be very difficult to replace plastic.理论上讲 玻璃和纸可以代替塑料 Glass and paper can theoretically replace plastic但这将会耗费巨大的成本 but this would come at a great cost.所以它们又很难代替塑料 Firstly,it would prove to be expensive首先 它确实是昂贵的 Secondly,as paper is made from trees,其次 由于纸是由树木制作而成的 they can prove to be a disaster for the environment.用纸取代塑料 对环境是场灾难 The electronics industry would greatly suffer随着塑料在各地的广泛使用 as plastic is widely used everywhere从电脑到智能手机 from computers to smartphones.电子产业都将受到严重影响 To conclude,总之 与其禁止使用所有塑料制品 不如禁止使用一次性塑料制品 这似乎是世界正期待的一种解决方案
  • 2022-06-27疫苗的诞生A world without vaccines would be a very dark place indeed.没有疫苗的世界一定是个非常黑暗的地方 Vaccine access is, indisputably, one of the biggest perks to living in the 21st century疫苗接种无疑是生活在21世纪最大的福利之一 – especially considering vaccination saves the lives of two to three million people every year,尤其是疫苗每年能拯救两到三百万条生命 and prevents the spread of some of the deadliest viruses in the world.还可以预防某些致命的病毒在世界上传播 “Hey, remember that time you got Polio?”“嘿 记得你患过小儿麻痹症吗? No, you don’t,没错 你不记得 because your parents got you f—ing vaccinated.”因为你的父母给你接种疫苗了 ” That said, it is important to recognize the degree to which vaccines are also a privilege.就是说 认识到接种疫苗也是某种特权很重要的 After all, not every nation has the same easy access to vaccines毕竟 不是每个国家都像富裕国家一样 that is enjoyed in wealthy countries.很容易就能打上疫苗 Even today, 1.5 million people across the world still die every year from vaccine-preventable diseases.即便是现在 全球每年仍有150万人死于打疫苗就能预防的疾病 Nonetheless, it’s a profound medical success that不管怎么说 疫苗仍是一项具有深远意义的医学成就 once-terrifying diseases such as measles, diphtheria,美国靠疫苗几乎消灭了曾经让人陷入恐慌的 and rubella have nearly been eradicated in the U.S.风疹 白喉 麻疹等疾病 One disease that has been fully wiped out, outside of laboratory samples,有一种在实验室之外已被彻底消除的疾病 was the first disease that humans were ever inoculated against – smallpox.也是人类首次接种对抗的疾病 -天花 You don’t hear much about smallpox today,如今你听不到太多关于天花的事 and that’s largely because nobody has died of it since 1978.主要是因为 自1978年后 没有人再死于天花了 But it’s easy to forget that但人们很容易忘记 smallpox was easily one of the deadliest scourges ever to face the human race天花曾是人类所面对的最致命的灾害之一 ripping through the world’s population on a scale far greater than the plague在剥夺生命时 比瘟疫的规模更甚 – and killing countless people for thousands upon thousands of years.在数千年间杀死了无数人 Evidence of deaths from smallpox go back to 1157 BCE,天花害人的证据要从公元前1157年说起 and it continued wiping away populations up through the 11th and 12th centuries,11世纪到12世纪 天花不断夺走人类的生命 where it was carried through Europe by soldiers returning from the crusades.天花由十字军东征归来带回欧洲 A few hundred years later,几百年后 the disease was brought by Spanish conquistadors to the New World,这疾病被西班牙征服者们带去新世界 where it may have been a key factor in the extinction of the Aztecs它可能是阿兹特克人灭绝的罪魁祸首 – who had not developed any immunity to the disease.阿兹特克人对它没有任何免疫力 The point is, smallpox has been around for much of human existence,关键是 天花差不多伴随着人类存在的大部分时间 and nothing ever really slowed it down,而又没有任何东西切实阻断天花传播 until vaccines came along, that is.直到疫苗出现 The degree to which vaccines turned the tide against this disease cannot be underestimated.疫苗对阻断天花传播功不可没 And a great deal of the credit for popularizing inoculation而且 推广疫苗接种的功劳 should go to an 18th-century woman named Lady Mary Montagu.应属于十八世纪的玛丽•蒙塔古夫人 Mary Montagu had faced smallpox firsthand.玛丽•蒙塔古曾直接接触过天花 It killed her brother, scarred her face,天花带走了她的弟弟 毁了她的脸 and left a profound impact on her future.还深深影响了她的未来 Later, when she visited Turkey,后来 在土耳其时 she was astonished to witness an old woman她吃惊地发现一位老妇人 who would go to people whose relatives had become sick会带着少量天花 – carrying with her small amounts of smallpox.去探望病人的亲戚 Once there, the woman would inject this liquid into到了那里 她就用针管把这些液体注射到 the other family members with needles.其他家庭成员体内 This is known as variolation,这被称为天花接种 an early form of inoculation.是早期的接种方式 Variolation of various sorts had been practiced long before the 18th century,多种引痘方式早在18世纪前就有实践了 but it had never gone widespread,但从未广泛传播 and the old woman inspired Mary Montagu to而这老妇人启发了玛丽•蒙塔古 have her own children inoculated.来给自己的孩子接种 Then, with great effort,然后 在费了大力后 she managed to to convince others in Great Britain to do the same.她说服了英国的其他人来做同样的事 This was no easy task, of course.当然 这不是件容易的事 Mary’s arguments were met with widespread mockery by the medical community,玛丽的观点遭到了医学界的一致嘲讽 who couldn’t believe the gall of a woman challenging male thinking.他们无法相信女性有胆量挑战男性的权威 And that’s to say nothing of the money这还没讲他们用 they made ripping people off with ineffective smallpox treatments.无效的天花疗法来抢黑心钱呢 However, Lady Mary didn’t back down,然而 玛丽女士没有退缩 and when another smallpox epidemic emerged in London,当另一场天花疫情在伦敦出现时 she made a point to publicize the inoculation of her daughter.她通过公开给女儿接种的成功证明了自己的观点 Unfortunately, despite changing a number of minds,不幸的是 尽管这改变了一些人的想法 inoculation still didn’t quite become mainstream.接种仍然没有成为主流 Worse still, due to Lady Mary’s gender,更糟的是 由于玛丽夫人的性别 her incredibly important role in medical history has often been ignored.她在医学史上的重要作用经常被忽略 The next big step forward occurred in 1796.下一个重大的发展是在1796年 An English country doctor named Edward Jenner proved that名为爱德华•詹纳的英国村医证明了 by taking fluid from a smallpox blister and injecting it into human skin,从天花水疱提取的液体注射到人类皮肤中 that person would not only not develop smallpox,这不仅不会令人得天花 but be vaccinated from future outbreaks.而且还可以预防天花在未来的爆发 Jenner demonstrated his case on a young boy named James Phipps,詹纳在一个名叫詹姆斯·菲普斯的男孩身上演示了他的案例 and his proof of concept inspired countless other physicians他对概念的论证激励了无数欧洲大陆的医生 across the continent to do the same procedure.来做同样的程序 Based on Jenner’s example,参照詹纳的例子 a wave of new vaccines for various diseases接下来的几个世纪里 were developed over the next few centuries,一批用于不同疾病的新型疫苗被开发出来 thus freeing much of human society from once-deadly plagues从而使人类社会摆脱了曾经致命的瘟疫 such as whooping cough, polio, measles, mumps, and, of course, smallpox.如百日咳 小儿麻痹症 麻疹 腮腺炎 当然还有天花 Check out one of our newest videos right here!看看我们最新的视频 Plus, even more Grunge videos about medical history are coming soon.此外 更多关于医学史的视频也即将推出 Subscribe to our YouTube channel订阅我们的youtube频道 and hit the bell so you don’t miss a single one.并设置提醒这样就不会错过任何一个
  • 2022-06-27电的实际工作原理I made a video about a gigantic circuit我曾制作了一个巨型电路相关的视频 with light-second long wires that connect up to a light bulb,该电路用1光秒长的电线连接着1个灯泡 which is just one meter away from the battery and switch,从电池到开关仅有1米长 and I asked you, after I closed the switch,现在我问你 开关闭合之后 how long will it take for us to get light from that light bulb?灯泡亮起需要多长时间? And my answer was 1/c seconds.我的答案是3亿分之1秒 And his answer is wrong!他的答案是错误的! We would be able to communicate faster than the speed of light!我们的通讯速度将会比光速还快! That violates causality and common sense.这有悖于因果关系和常识 This is actually a bit misleading.这实际上有点误导 Misleading.误导 Misleading in a way.某种意义上误导了 Extremely unconvinced.太难以令人信服了 Naughty Mr. Veritasium has stirred up a right hornet’s nest.调皮的真理先生捅了马蜂窝了 Clearly I did not do a good job of explaining what was really going on in the last video.很显然上个视频中发生的事 我解释得不太清楚 So I wanna clear up any confusion that I created.所以我想澄清一下这些我所制造的困惑 So behind me, we have a scaled down model of this circuit.在我身后 是按该电路的等比缩小的模型 It is only 10 meters in length on either side.两边仅有10米长 Obviously that’s a lot shorter than one light-second,显然 比1光秒短很多 but for the first 30 nanoseconds,但是对于第1个30纳秒而言 this model should be identical to the big circuit,这个模型与该巨型电路是相同的 and Caltech has very fast scopes,加州理工学院有高速示波器 so we’ll be able to see what’s going on in this time.所以我们将会弄明白这次的实验 I got a ton of help on this from Richard Abbott,Richard Abbott 给了我很多帮助 who works on LIGO, the gravitational wave detector.他在引力波探测天文台LIGO工作 Over here, we are going to put a little resistor,在这里我们要加一个小电阻 which is gonna be the stand in for our light bulb作为灯泡的替代物 and we’re going to measure it with a scope and see essentially,然后我们将用一个仪器进行测量 what is the time delay between applying a pulse看看在电路的一边施加脉冲 on the other side, basically flicking the switch,另一边仅是打开开关 电阻两端 for us to get a voltage across our resistor.产生电压需要的时间到底是多久 And the magnitude of that voltage is really important.该电压的强弱十分重要 A lot of people thought it would be negligible.很多人觉得它无关紧要 The amount of energy supplied by this is so minuscule.它提供的能量数值微不足道 A tiny, tiny effect, right?只造成极小 极小的影响 对吗? The amount of power you’re getting to the lamp over here, it’s nuff-all这个大小的能量对此电灯来说足够了 He meant the light turns on他的意思是 在任何电流强度下 at any current level immediately.这个灯泡都会立刻亮起来 That is not what I meant.我不是这个意思 Well, actually, with that assumption,呃 实际上 在这种假设下 Derek’s answer is wrong.Derek 的答案是错误的 The light never turns off no matter the state of the switch.不论开关打开还是闭合 电灯一直没被关掉 Some electrons will jump the gap有些电子可以跳过这个间隙 and result in an extremely small continuous leakage current.然后产生一种极小的 持续的 泄漏电流 Let me be clear about what I am claiming.让我清楚地解释一下我的观点 Okay, it is my claim that we will see voltage and current,好 我的观点是我们将会看到 through the load that is many orders of magnitude greater than leakage current,比泄漏电流大许多数量级的电压和电流 通过负载 an amount of power that would actually produce visible light,这样大小的电流通过一个合适的装置 if you put it through an appropriate device.它将会产生可见光 And we will see that power there in roughly the time并且大概在电流通过这一米的间距所需时间之后 it takes the light to cross the one meter gap.我们将会观察到发光现象 But to understand why this happens,但是为了理解这事发生的原因 we first have to clear up some misconceptions首先 我们要扫除我在评论中 that I saw in responses.看到的一些错误观念 Misconception number one is thinking that electrons错误观念一:认为电子 carry the energy from the battery to the bulb.把电池中的能量带给灯泡 Let’s say we have a simple circuit with a battery and a bulb,假设我们用一节电池和一颗灯泡做成了 operating at steady state.一个运行稳定的简单电路 If you zoom in on the light bulb filament,如果放大灯泡的灯丝 you’d see a lattice of positively charged cores of atoms.你会看到带正电的原子核组成了晶格 The nucleus and lowest shells of electrons这些原子核和最底层的电子 surrounded by a sea of negative electrons,被海量的 可以在晶格内 which are free to move around the lattice.自由移动的负电子包围着 The actual speed of these electrons is very fast,这些电子的实际移动速度很快 around a million meters per second,高达一百万米每秒 but all in random directions.但移动的方向都是随机的 The average drift velocity of an electron一个电子的平均漂移速度 is less than 0.1 millimeters per second.小于0.1毫米每秒 Now frequently, an electron will bump into a metal ion,电子漂移时常会碰撞金属离子 and transfer some or all of its kinetic energy to the lattice.部分或全部动能会被转移到晶格中 The electron slows down and the metal lattice starts waggling more.电子速度变缓 该金属晶格摆动开始增加 It heats up.它的温度升高 And ultimately this is what causes the filament to glow and emit light.最终导致灯丝慢慢发光发亮 So a lot of people will look at this and conclude所以很多人看到此处会认为 the electron carried the energy from the battery to the bulb电子携带电池的能量到达灯泡 where it dissipated its kinetic energy as heat,并在此处把动能释放为热能 but consider, where did the electron get its kinetic energy但是思考一下 在碰撞发生之前 from before the collision?电子的动能来自哪里? It didn’t carry that energy from the battery.它携带的动能并非来自于电池 In fact, if the circuit has only been on for a short time,事实上 如果此电路只是短时间通电 that electron hasn’t been anywhere near the battery.那这点时间还不够电子漂移到电池的附近 So how was it accelerated before the collision?因此 在碰撞之前 电子怎样加速呢? The answer is, it was by an electric field in the wire.答案是:靠电线内部的电场加速 The electron repeatedly collides with the lattice, and loses energy.电子与晶格反复碰撞并丢失能量 And after each collision, it is again accelerated by the electric field.每次碰撞后 电场再次给电子加速 So although it is the electron that transfers energy因此 虽然是电子将能量转移到晶格 to the lattice, the energy came from the electric field.但是 该能量却来自于电场 So where does that electric field come from?那么电场又来自于哪里? Well, a lot of animations make it look like the electrons呃 很多动画制作得好像 push each other through the circuit via their mutual repulsion.电子通过相互排斥 推动彼此通过电路 So you might think the electric field所以 你可能会认为电场 comes from the electron behind it.来自于它背后的电子 There is the analogy of water flowing through a hose,类似于从水管流出的水 or marbles in a tube.或者从管道滑出的弹珠 This is misconception two, thinking that这是第二个错误观念 mobile electrons push each other through the circuit.认为流动电子推动彼此通过电路 That is not how electrons flow in circuits.这不是电子流过电路的方式 The truth is if you average over a few atoms,事实是 如果按几个一组将原子平分 you find the charge density你会发现导体内部 everywhere inside a conductor is zero.任何地方的电荷密度都为0 The negative charge of electrons电子的负电荷 and the positive cores of atoms perfectly cancel out.和原子核的正电荷完美地抵消了 So for each repulsive force between electrons,因此 对于电子之间的每一个斥力而言 there is an equal and opposite force旁边的正离子对它有一个 from the positive ion next to it.大小相等 方向相反的作用力 These forces cancel out.这些力相互抵消 So mobile electrons cannot push each other through the wire.所以流动电子不能推动彼此通过电线 So where does the electric field come from?那么电场从何而来? Misconception number three is that it comes entirely from the battery.错误观念三 认为电场完全来自于电池 This makes intuitive sense,从直觉上讲 这说得过去 since the battery is the active element in the circuit,因为在电路中电池是有源元件 it has a positive side and a negative side.它有一个正极和一个负极 So it has an electric field,所以它会产生一个电场 But this is not the electric field但此电场并不是那个 that all the electrons within the wire experience.电线内所有电子都会经过的电场 Consider that the electric field考虑到靠近电池的地方 of the battery is much larger close to the battery.电池产生的电场会强得多 So if its field were really what’s pushing the electrons around,因此 如果电子真是由电池的电场推动的 then if you brought the light bulb close to the battery,那么如果让灯泡靠近这个电池 then the bulb would glow much brighter.灯泡就会变亮许多 And it doesn’t.然而并没有 The truth is that the electric field in the wire事实是 电线中的电场 comes both from the battery and from charges不仅来自于电池 也来自于 on the surface of the wires of the circuit.该电路中 电线表面的电荷 As you go along the wire from the negative end of the battery to the positive end,沿着电线 从电池的负极到它的正极 there is a gradient of charge built up on its surface,电线的表面便会形成一个电荷梯度 starting with an excess of electrons,开始时有大量的电子 through to roughly no charge in the middle,直到中间几乎没有电荷 as we’ll see the steepest charge gradient is actually正如我们所见 电荷梯度最大处 其实是 across the load to a deficiency of electrons,横跨负载 通向电子缺乏端的地方 the exposed positive cores of atoms on the surface那里 带正电的原子核 of the positive end of the wire.位于电线带正电的末端表面 All these charges and the charges on the battery所有的这些电荷以及电池的电荷 create the electric field everywhere inside the wires.在电线内部 创造了无处不在的电场 They also create an electric field in the space around the wires.它们也在电线周围的空间内 创造了电场 These surface charges were set up almost instantaneously一旦把电池安装到电路中去 when the battery was inserted into the circuit.就会立刻形成这些表面电荷 You might think you’d have to move electrons你可能认为 电子必须移动很长的距离 a significant distance to create this charge distribution,才能形成这样的电荷分布 but that is not the case.但事实不是这样 Even a slight expansion or contraction of the electron sea,即使是电子均匀地移动一个质子的半径的距离 with electrons moving on average, the radius of a proton,造成的电子海的轻度扩张和收缩 can establish the surface charges you see.都可以形成你所看见的表面电荷 So the time for the charges to move所以电荷移动所花费的时间 is completely negligible.完全可以忽略不计 The speed of the setup process is limited表面电荷形成的速度 only by the speed of light.只受光速的限制 Once that surface charge distribution has been established,一旦表面电荷分布形成 the battery does continuous work to maintain it,电池持续地逆着库仑力移动电子流过电池 by moving electrons through the battery against the Coulomb force.来维持表面电荷的运行 In the load, the electric field在负载灯泡内部 created by all the surface charges, accelerates electrons,表面电荷创造了电场 电场加速电子移动 which dissipate their energy in collisions with the lattice.加速的电子在碰撞中将能量转移给晶格 So the battery is putting energy into the field,因此电池将能量释放到电场 which electrons take out and transfer to the load.电子带出这些能量 并转移给负载灯泡 An electrical engineer who made a response video,一位叫Ben Watson的电气工程师制作了一个回应视频 Ben Watson, came up with a good analogy.他想出了一个很好的类比 The battery is like a shepherd.电池就像牧羊人 The surface charges are the sheep dogs表面电荷是牧羊犬 responding to his orders.服从牧羊人的命令 And the mobile electrons are the sheep,移动的电子是绵羊 guided by those barking dogs.由那些吠犬引导 The surface charge description of electric circuits大部分教科书中删去了 is omitted from most textbooks,对于电路的表面电荷的描述 but there is a great treatment of it但是Chabay 和Sherwood却在 in Matter and Interactions by Chabay and Sherwood.《物质与相互作用》一书中着重描述了这个知识 They also have a VPython simulation where you can see他们还建立了一个VPython仿真 the positive surface charge in red,模型中 正极的表面电荷是红色的 and negative surface charge in blue.负极的表面电荷是蓝色的 You can see how this entire charge distribution你可以看到整个电荷分布是如何 creates a net electric field shown by the orange arrow,在电路的内部和周围以及电线的内部 everywhere in and around the circuit,创造一个 如橙色箭头所示的 everywhere inside the wire,无处不在的净电场 The electric field has the same magnitude该电场有相同的强度 and its direction is along the wire.并且它的方向是顺着电线的 This is really showing you the electric field这个模型真实地向你展示了 in the center of the wire, but it’s depicted on the surface电线中心的电场 只不过它是画在表面的 so you can see it.所以你可以看到它 In this circuit,在这个电路中 all the conductors are made of the same material,所有的导体都是由相同的材料做成的 but the segment at the bottom但是下面这部分的 has a much narrower cross section.通过路径更为狭小 So it represents a resistor.所以这代表了一个电阻 Since the cross sectional area is smaller,由于这个通过路径区更小 the electron drift velocity through the resistor通过这个电阻时 电子的漂移速度 has to be higher so that it can carry the same current必须要更快 这样才能与电路中 as everywhere else in the circuit.其他地方一样 携带相同的电流 Now, drift velocity is directly proportional to electric field.现在 漂移速度与电场成正比 So the electric field must be largest inside the resistor.所以 电阻内部的电场一定是最大的 And this is achieved by having the steepest gradient这种现象得以实现 是因为 of surface charges here.这里的表面电荷的梯度最大 You can also see the contribution to the net electric field你也可以看到 紫红色箭头 from the battery in magenta,代表电池带来的电场 and the contribution from surface charges in green.绿色箭头代表表面电荷带来的电场 Far from the battery,在远离电池的地方 most of the electric field is due to surface charges,大部分的电场是表面电荷带来的 whereas close to the battery, it has a greater contribution而电池的近端 电池带来的电场占比更大 and the field due to surface charges并且表面电荷产生的电场 is actually in the opposite direction实际上与电池产生的电场 to the field from the battery.方向相反 So to sum up, electrons don’t carry the energy总得来说 电子既没有从电池处 from battery to bulb,携带能量到灯泡 nor do they push each other through the wire.也没有推动彼此通过电线 They are pushed along by an electric field,电池的电荷产生的电场 which is created by charges on the battery,以及电线的表面电荷产生的电场 and charges on the surface of the wires.推动着它们前进 With this view of circuits,带着这种观点看电路 things that might have previously seemed mysterious,原本似乎很离奇的事情 make a lot more sense.就解释得通了 Like if electrons leave a battery at the same rate,比如 如果电子离开电池 and with the same drift velocity as they return,和回流的时候速度一样 how do they carry energy from the battery?那么 它们怎么从电池带走能量? The answer is they don’t.答案是 它们没有带走能量 They are accelerated by the electric field在电子与晶格发生每次碰撞之前 before each collision with the lattice.电场会给电子加速 At a junction, how do the correct number of electrons在结点处 电子是怎样以正确的数量 go down each path?通过每条路径? Well, they’re guided by the electric field, which extends everywhere throughout the circuit.呃 它们被处处存在的电场引导着 The fields are the main actors,电场才是主要因素 extending everywhere throughout the circuit,它们遍及电路的每个角落 and the electrons are just their pawns.而电子只是它们的小兵 So how does this apply to the big circuit?所以这是如何作用于那个大电路的呢? When the battery is connected into the circuit,当把电池连入到电路时 even with the switch open, charges rearrange themselves.即使开关没有闭合 电荷也会自动重新分布 On the negative side of the battery,在电池的负极 there is an excess of electrons电线和开关的表面 on the surfaces of the wires and the switch.有大量的电子 On the positive side, there is a deficiency of electrons.而正极缺少电子 So positive charges built up on the surface of the wires.所以正电荷分布在电线的表面 The charges rearrange themselves until the electric field电荷自动重新分布 直到 is zero everywhere inside the conductor.导体内部所有地方的电场都为0 This electric field is due to all the surface charges电场由所有表面电荷产生 and the charges on the battery.以及电池的电荷 There is an electric field outside the wires这些电荷使得电线外部形成一个电场 due to these charges, but it’s zero inside the wires.但是电线内部的电场为0 We now have the full potential difference现在我们知道了电池通过开关 of the battery across the switch.形成了全电势差 And no current is full flowing, except for leakage current,除了泄漏电流 完全没有电流能够流通 which I’ll assume is negligible.而我假设泄漏电流是可以忽略不计的 When we close the switch,当开关闭合时 the surface charges on both sides of the switch开关两边的表面电荷 neutralize each other on contact.在接触时会彼此抵消 And at that instant,在那一瞬间 the electric field inside the conductor is no longer zero,导体内部的电场不再为0 and current starts flowing through the switch.电流开始流过开关 Simultaneously, the new electric field from the modified surface charges同时 改变后的表面电荷产生的新的电场 radiates outwards at essentially the speed of light.基本上以光速向四周辐射 And when it reaches the bulb,当它辐射至灯泡时 the electric field inside it is no longer zero.灯泡内部的电场就不再为0 So current starts to flow here too.因此电流也开始在此处流通 This is why I said the bulb lights up in 1/c seconds,这就是我说灯泡亮起需要3亿分之1秒的原因 because the bulb was one meter from the switch,因为灯泡离开关有1米 and the change in the electric field travels out at the speed of light.并且电场的变化以光速向外传播 As some of you pointed out,正如一些人指出的那样 the answer should have been one meter divided by C.答案本应该是1米除以光速 And I apologize for the casual use of units.我很抱歉单位上用得比较随意 If you were to move the switch,如果移动这个开关 then the bulb would take那么这个灯泡亮起 a different amount of time to emit light,需要的时间将会变得不一样 which just depends on the distance这个时间取决于 between the switch and the bulb.开关和灯泡的距离 In response to my original video,为了回应我的原始视频 Ben Watson simulated a model of the circuitBen Watson用Ansys的一款叫做HFSS的软件 using software from Ansys called HFSS.给这个电路建模 It provides a complete solution to Maxwell’s equations in three dimensions.它给出了三维麦克斯韦方程的完全解 Now I have worked with Ben and Ansys现在我与Ben合作 利用Ansys软件 to make these simulations.制作出这些仿真 When the switch is closed,当此开关闭合 you can see the electric field radiate out,你可以看到这个电场向外辐射 and as it hits the far wire, it generates current.当它到达远处的电线 就产生电流 The electric field is to the right.电场方向向右 So the electrons flow to the left.所以电子流向左边 This simulation shows the magnitude of the magnetic field,这个模型展示了磁场的大小 which falls off pretty rapidly as it crosses the gap.当通过这个间隙时 该磁场衰退得非常快 But then a magnetic field appears around the far wire,但随后在远处的电线出现了一个磁场 and this magnetic field is created by the current in that wire.该磁场是由电线中的电流产生的 To me, this suggests that it really is the electric field,这就让我想到 其实是电场 and not the changing magnetic field而不是这个正在变化的磁场 that creates the current through the load.创造了通过负载的电流 Some commenters on the original video原视频底下有人评论说 claimed my answer of three or four nanoseconds我的答案 3到4纳秒 violates causality.违背了因果关系 I guess they were thinking that the bulb我猜他们认为 would only go on if the circuit were complete.只有电路接通 灯泡才会亮起 And it wouldn’t if the circuit were broken somewhere,而如果电路在半光秒内的某处断开 which could be up to half a light second away.灯泡就不会亮 So it seemed like I was saying,所以这就像是我在说 we could get information about the status即使在半光秒开外的地方 of the whole circuit, even half a light second away,仅需几纳秒 我们就可以得到 in just nanosecond seconds.关于整个电路状态的信息 But that is not what I was saying.但我不是这个意思 What I should have stated explicitly,我本应清楚地表明 is that the bulb goes on不论电路是否接通 regardless of whether the circuit is complete or not.该灯泡都会亮起 The current flows through the load电流流过负载灯泡 due to the electric field it experiences.是因为它处在电场中 To illustrate this, Ben added a wire below the circuit为证明这点 Ben在该电路下增加了一条电线 that is completely disconnected from it.这条电线与该电路完全没有连接 You can see is that its response你可以看见下面这条电线 to the changing electric field is virtually identical对这个正在改变的电场的反应 to that of the top wire,与上面的电线几乎完全相同 at least up until the signal reaches the far end至少一直上升 直到该信号到达远端 and reflects back.并反射回来 This is why my answer doesn’t break causality.这就是我的答案没有违背因果关系的原因 At least initially, connected and disconnected wires至少开始时 已经接通的电线和 behave exactly the same.没有接通的电线的表现完全相同 Using this software,使用这个软件 you can also simulate the Poynting vector你也可以模拟坡印廷矢量 that is the cross product of electric and magnetic fields.即电磁场的叉积 In the last video, I showed how the Poynting vector在上个视频中 我展示了坡印廷矢量 indicates the direction of energy flow.是如何指示能量流动的方向的 And after the switch is closed,开关闭合后 不论另一根电线 the Poynting vector points out of the battery,是否接通 坡印廷矢量都会穿过这个间隙 across the gap to the other wire, whether connected or not,指向电池之外 到达另一条电线 because energy is carried by fields and not electrons,因为能量是由电场 而不是电子携带的 it can go straight across the gap.所以能量可以直接穿过这个间隙 So you might ask, why do we need wires at all?你可能会问 那为什么我们仍然需要电线呢? Well, we don’t, I mean, phones and toothbrushes呃 不需要 我的意思是手机和牙刷 charge without wires connecting them在没有电线连接输入电子流的情况下 to a stream of electrons,仍然可以充电 and researchers have demonstrated remote charging并且有研究表明 使用来自WiFi信号的能量 using the energy from WiFi signals.也可以远程充电 Wires are more efficient because they channel the fields电线效率更高是因为它们可以引导电场 and hence the energy from source to load.因此能量可以从电源到达负载 Here’s another angle on the Poynting vector.从另一个角度看坡印廷矢量 And you can see once there is current in the top wire,你可以看见 只要上面的电线内有电流 the fields around it carry energy in both directions.它周围的场从两个方向带走能量 Now, of course, the Poynting vector also points现在 当然 正如大多数人期待的那样 parallel to the first wire,坡印廷矢量 carrying the energy around the circuit指向与第一根电线平行的方向 as most people would expect.携带能量绕着电路走 But again, note how the energy is carried outside the wires,但是再说一遍:注意能量是怎样被带出电线的 not in the wires.而不是局限于电线内 Now admittedly, thinking about circuits this way现在不可否认 这种看待电路的方式 is complicated.是复杂的 And since nobody wants to solve Maxwell’s equations仅仅是为了分析一个基本的电路 in three dimensions just to analyze a basic circuit,没人愿意用三维麦克斯韦方程组解决 scientists and engineers have worked out shortcuts.科学家和工程师想出了简便方法 For example, Ohm’s law,例如 欧姆定律 voltage equals current times resistance,电压等于电流乘以电阻 is just the macroscopic result of all the surface charges,仅仅是所有的表面电荷 their electric fields and zillions of electrons它们的电场以及无数的电子 bumping into zillions of metal ions.与无数金属离子间碰撞的宏观结果 You can simplify all that physics你可以把所有那些物理元素 into a single circuit element, a resistor,简单归结为一个单一的电路元件 电阻 and the basic quantities of current and voltage.以及基本量 电流和电压 This is called the lumped element model,这就是所谓的集总元件模型 lump all the spread-out multi particle and field把所有分散多质点和场的交互作用 interactions into a few discrete circuit elements.归并为少量的离散电路元件 And we use this technique每次我们画电路图时 every time we draw a circuit diagram.都会使用这个技巧 So our original diagram of the big circuit is flawed因此该大电路的原始电路图是有缺陷的 because fields between the wires are important to the problem,因为电线间的场对这个问题也很重要 but there are no circuit elements to indicate these interactions.但是没有电器元件指出这些交互作用 To fix it, we need to add capacitors all down the wires.为了修正它 我们需要沿着电线添加电容器 These capture the effect charges on one wire这些电容器能够捕获一条电线的电荷 have on the other.对另一条电线的影响 If there are negative charges on the surface of the bottom wire, for example,例如 如果下面这条电线的表面电荷为负 they’ll induce positive charges on the surface of the top wire.那它们会在上面这条电线的表面产生正电荷 Also, since these wires are long,并且 由于这些电线太长了 they’re gonna create significant magnetic fields所以在它们周围将会产生显著的磁场 around them, which resist changes in current.这些磁场能让电流保持不变 So we model this with inductors all the way down the wires.所以我们沿着电线用电感模拟了该现象 We could also add resistors,我们本来也可以加入一些电阻 making what electrical engineers would recognize建立一个电气工程师所说的 as the distributed element model for a transmission line.“输电线路的分布式元件模型” But we’re assuming that these wires are super conducting.但让我们假设这些是超导电线 So this is how we could model所以我们是这样模拟 a super conducting transmission line.一条超导输电电路的 This diagram offers another way of understanding这个电路图提供了另外一种 why current flows through the load almost immediately.理解为什么电流能立刻流入负载的方式 When you first apply a voltage across a capacitor,当你第一次给一个电容器施加电压时 current flows as opposite charge builds up由于两个极板产生了相反的电荷 on the two plates.电流得以流动 In the short time limit, a capacitor is a short circuit.在有限的短时间内 一个电容器就是一个短电路 It acts just like an ordinary wire.它表现得就像一根平常的电线 Once it’s charged up, no more current flows,一旦电容充满了 电流就不再流过 but by this point, the next capacitor is charging up.这个时候 下一个电容器正在充电 And then the next one, and then the next one.然后是下一个 再下一个 And so we have a loop of current that is expanding out这就形成了一个大约以光速 at roughly the speed of light.向外扩展的电流环路 This is of course, just another way of talking当然 这只是用另外一种方式来讨论 about the effect the electric field下面这条电线的电场 from the bottom wire has on the top wire.对上面这条电线的影响 One reason it’s useful to look at the circuit this way,用这种方式看待这个电路是有效的 is because you can use the values of inductance一个理由是 你可以利用电感值和电容值 and capacitance to calculate the characteristic impedance of the transmission lines.来计算这些输电线路的特性阻抗 You can think of this as the resistance你可以把特性阻抗 看作 to alternating current that a source would see电源向电线发送信号时 when sending a signal down the wires.对交流电产生的阻碍作用 The characteristic impedance is equal to the square root该特性阻抗等于 of inductance divided by capacitance.电感除以电容之商的平方根 And for our circuit,对于我们这里的电路而言 I measured the capacitance and the inductance of the lines,我测量了线路的电容和电感 11.85, call it, microhenrys.11.85 单位 微亨 So we got a characteristic impedance of about 550 Ohms.所以特性阻抗大约是550欧姆 To maximize the power delivered to our load,为了求出传输给负载的能量的最大值 we want its resistance to equal the sum of the other我们让它的电阻等于该电路中 impedances in the circuit.其他阻抗的总和 So that’s why we picked a 1.1 kilo-Ohm resistor.所以我们才选择了一个1.1千欧的电阻 Now, I hope you’re convinced that current will flow现在 我希望“电场一到达电线远端 as soon as the electric field reaches the far wire.电流就会流动”这个道理已经说服了你 The question is, how much?问题是 数量是多少呢? Are we gonna see an appreciable voltage即使这些线路只有一米远 even with these lines a meter apart?我们也会测量到强大的电压吗? That’s what it seemed like a lot of people were doubting in the last video.在上个视频中很多人对此似乎有疑问 So that’s really what we want to find out here.所以在这里我们真的想要找出答案 Okay, so now we’re putting a pulse in there.好 现在我们会在这里施加一个脉冲 Yep.嗯 Well looky, looky, Derek.啊 看哪看哪 Derek So what do we got that yellow one is our-所以显示了什么 那个黄色的是? Got a fraction of the applied voltage overshoot.显示出外加电压过冲的一个片段 So it looks to me like the initial voltage所以在我看来现在的原始电压 that we’re getting is about five volts per division.大概每格电压值是5伏 So it looks like about five volts,看起来大概是5伏 roughly four or five volts.大概4到5伏 The green curve rising up to around 18 volts is the source voltage.上升至18伏的绿色曲线是电源电压 And the yellow line is the voltage across the resistor.黄色的线是电阻两端的电压 So after just a few nanoseconds,所以仅在几纳秒之后 this voltage rises to around four volts.这个电压上升至大约4伏 Since the resistor was a kilo-Ohm,由于这个电阻是一千欧姆 that means four milliamps of current那就意味着在该信号环绕电路之前 are flowing in the resistor,有4毫安的电流 before the signal goes all the way around the circuit.正在流经这个电阻 So we were transferring about 14 milliwatts of power.所以我们传输了14毫瓦的能量 This is what 14 milliwatts of light actually looks like.这就是14毫瓦的灯亮起来的样子 So, yeah, it’s not a fully on bulb,的确 它不是一个完全亮起来的灯泡 but it is visible light and way more than you would get但它是可见光 并且比泄漏电流 from just leakage current.能产生的光要亮得多 Now, some of you may argue,现在 一些人可能会质疑 it’s unfair to use a little LED when I showed a bulb在原始视频中我使用的是一个灯泡和车载电池 and car battery in the original video,而现在用一个小LED灯是不公平的 but those items were for illustrative purposes only.但这些物件只是为了解释说明而已 The clue that this is actually a thought experiment这实际上是一个思维实验 想法就是 is the two light-seconds of super conducting wire使用两根30万千米长的 that stretch out into space.延伸至太空的超导电线 This is not an engineering question about how best这不是一个类似于怎样在你的卧室 to wire up a light bulb in your bedroom.用最优方式安装灯泡这样的工程问题 The question was intentionally vague.我故意没有明说这个问题 And if you want to choose circuit components如果你想选用几种 such that the bulb never goes on,让灯泡永远不会亮的电路元件 you are welcome to do that我表示很欢迎 and I support your conclusion.并且我支持你的结论 Just to me, the most interesting way只不过对我而言 解决这个问题 to approach this problem is to ask,最有趣的方式是去发问: how could you make the light go on fastest?怎样才能让这个灯泡最快地亮起来? I was worried that those long wires would pick up我本来还担心那些电线会 all the radio waves passing through,传输所有经过它们的无线电波 and we wouldn’t even be able to see the signal for that noise,由于噪音的存在 我们甚至都无法分辨出信号 but you can see clearly on the graph但是你可以在图表上清楚地看见 that the signal is way above the noise level.这些信号远在噪音水平之上 Alpha Phoenix set up a kilometer of wireAlpha Phoenix建了一个一千米的电路 and got a very similar result.并得到了相似的结果 So the light bulb turns on a little bit,所以 这个灯泡亮了一点 and then after one light-speed delay,1光速之后 the light bulb turns on the rest of the way.这个灯泡便一直亮下去了 YouTuber, ZY, simulated the transmission line circuit,油管人ZY模拟了这个输电线路 and found that even with realistic assumptions,然后发现即使在现实假设之下 he transferred 12 milliwatts to the load straight away.他立刻向负载传输了12毫瓦 Derek is actually more correct than we give him credit for.Derek实际上比我们所认为的更正确 So, I believe that he’s correct on all counts.所以我完全相信 他是正确的 And the question is neither deceptive那么 这个问题并不具有迷惑性 or requires like technicalities.也不需要技术性的细节 So everyone agrees that a steady, small,所以每个人都同意这个观点:在开关闭合之后 but way-bigger-than-leakage-current signal一种稳定的 小的 flows through the load in the first second但是远比泄漏电流大的信号 after the switch is closed.在第一秒时流经了负载 Is it enough to emit light?它足够使灯泡发光吗? Yes, if you use an LED.当然 如果你用的是一个LED灯泡 But the point of the thought experiment但是这个思维实验的意义在于 was to reveal something that’s normally hidden揭露一些在我们看待或者教授电路时 by the way that we think about and teach electric circuits.隐藏的的知识 You know, we use voltage and current and lumped elements你懂的 我们使用电压 电流和集总元件 because they’re more convenient是因为比起用麦克斯韦方程求解 than working with Maxwell’s equations,它们要更方便 but we shouldn’t forget that the main actors are actually the fields.但我们不能忘记 主要的因素实际上是场 They are what carry the energy,它们才携带能量 and you don’t have to take my word for it.并且这并不是我提出的观点 This is Rick Hartley,这是Rick Hartley a veteran printed circuit board designer.一位资深的印刷电路板设计师 I used to think in terms of voltage and current.我过去常常从电压和电流方面来思考 And I used to think that the energy in the circuit并且我过去常常认为电路中的能量 was in the voltage and current, but it’s not.存在于电压和电流中 但其实不是这样的 The energy in the circuit is in the fields.电路中的能量存在于场 The most important thing you need to know你应该了解的最重要的事情是 is that when you route a trace,当你跟踪一个路由时 you better define the other side of that transmission line,你最好明确一下输电线路的另外一边 because if you don’t, those fields are gonna spread因为如果你不这样做 这些场将会蔓延 and they’re gonna leave you an unhappy individual.你会不快乐 I think one of the things that I’m most excited我认为这个电路视频让我最激动的事情之一 about the circuit’s video was the response videos I saw是我看到了许多 由很多人特别是 by so many people especially people在电气工程方面比我更有资质的人 with far better credentials in electrical engineering than me.所制作的回应视频 I really enjoyed watching those videos.我真的很喜欢看那些视频 So I feel like my circuits video was kind of like,所以我感觉在我的电路视频中 a mistake on my part in certain ways我的一个错误是 that I didn’t delve deep enough在一定层面上 into this part of the problem.我没有足够深入探究这方面的问题 I honestly didn’t think that this was the focus of the video,诚然 我认为这不是该视频的重点 but clearly everyone who watched it did,但很明显 每个看过视频的人都觉得是 so that’s on me, but by making that mistake,所以这怪我 因为我犯了那个错误 and by not going deep into my explanation,而且没有深入地解释 I invited seemingly a whole bunch of other people我还邀请了另外一大群人来解释 to make explanations, which I thought were great.那些问题我原本以为已经解释得很棒了 And some people like Alpha Phoenix even took up并且其中有人 像Alpha Phoenix 甚至 the challenge and set up his own version of the experiment.接受了这个挑战并建立了他自己版本的实验 So, frankly, I’m just really excited at what came about,所以坦白讲 虽然我承认刚开始是我的错 even though I do acknowledge that this was my fault in the first place.但随之而来的事让我感到太激动了 Like I should have done a better explanation,我本应该做出更好的解释 but by not doing so, you know,但是你懂的 因为没有这样做 there are a lot of great explanations out there.所以涌现出了很多很棒的解释 And that’s what I love.这就是我乐于见到的 So I’m gonna recommend a whole bunch所以我想向你推荐一群 of electrical engineering YouTubers to you电气工程方面的油管人 in case you wanna check those out万一你要看一看他们的视频 because they’re a lot of great channels,因为他们的频道很棒 and you should really see how they think about electronics,你真该见识一下他们是如何思考电子学的 and how they explain this circuit.以及他们是怎样解释这个电路的 Hey, this video was sponsored by Brilliant,嗨 这个视频是由Brilliant网站赞助的 the website and app that gets you thinking deeply该网站和app能够让你对数学 科学 about concepts in math, science, and computer science.以及计算机科学的概念有深层次的理解 Brilliant is sponsoring a lot of our videos this year,今年Brilliant赞助了我们很多的视频 because they know someone who makes it to the end因为他们知道 of a Veritasium video is exactly the sort of person能把真理元素的视频看到结尾的人 who would love to learn with Brilliant.正是喜欢用Brilliant学习的那种人 And they have a great course on electricity and magnetism,并且在电学和磁学方面 他们有一个很棒的课程 which methodically steps you through an introduction这个课程用问题 模拟 视频和实验 to E&M with questions, simulations, videos, and experiments.系统地一步一步引导你入门电学和磁学 I really think this is the best way to learn我真的认为这是最好的学习方式 because the sequence of steps is so well thought out.因为这些步骤的顺序都是被精心设计的 The difficulty builds gradually.困难逐渐形成 And by asking you questions,并且通过询问问题 you are forced to check your understanding at each step.你不得不检查自己对每一步的理解 If you need help,如果你需要帮助 there’s always a useful hint or explanation.课程会有一个有用的提示或者解释 You know what sets Brilliant apart is their interactivity.让Brilliant与众不同的是它们的交互性 You can learn calculus or machine learning微积分 机器学习 or computer science fundamentals或者计算机科学基础 all in this very active way.你都可以用这种积极的方式来学习 So I encourage you to go over to brilliant.org/veritasium所以我鼓励你浏览brilliant.org/veritasium网站 and just take a look at their courses.去看一看它们的课程 I will put that link down in the description.我会把那个链接放在这段话的下方 And if you click through right now,并且如果你马上点击进入网址 Brilliant are offering 20% offBrilliant将会提供20% an annual premium subscription年度订阅费津贴 to the first 200 people to sign up.给前200名注册的人 So I want to thank Brilliant for supporting Veritasium.感谢Brilliant对真理元素的支持 And I wanna thank you for watching.感谢大家的观看
  • 2022-06-27神经流形——行为的几何学该视频为3Blue1Brown夏季数学博览会参赛作品 It is the Holy Grail of neuroscience神经科学的圣杯 to understand how the information is being represented inside the brain是了解信息是如何在大脑中 encoded in patterns of activity of nerve cells.以神经细胞的活动模式编码来表示的 On this quest, we make use of tools offered by在这次探索中 我们运用了 biology, physics, chemistry, computer science,生物学 物理学 化学 计算机科学 and of course, math.当然 还有数学 Today I’m super excited to tell you about a concept很高兴 今天我要告诉你们一个 that I think is just unbelievably beautiful.我觉得非常美妙的概念 We will discuss neural manifolds,我们将讨论神经导管 and how abstract mathematics of high-dimensional spaces以及如何利用高维空间的抽象数学 can be used to unravel the secrets behind the neural circuits.来解开神经回路背后的秘密 The video is structured in the following way.视频的结构如下 First we’ll refresh some very basic neuroscience concepts,首先 我们将回顾一些非常基本的神经科学概念 and see how we can extract data from the working brain:看看我们是如何从工作的大脑中提取数据的 from patterns of neurons activating,从神经元的激活模式 to points scattered in high-dimensional space.到分散在高维空间中的点 Then we’ll talk about shapes in these high-dimensional spaces,然后我们将讨论这些高维空间中的形状 and discuss what important characteristics they might have.以及它们可能具有的重要特征 Finally, we will bring everything together,最后 我们将把所有东西放在一起 mathematically describing the clouds of points we obtain from the active brain.用数学方法描述 从活跃的大脑中获得的点云 And using the discovery that was published two years ago in Nature as an example,我会以两年前发表在《自然》杂志上的一个发现为例 we’ll see what insights could be generated看看神经回路内的数据表示 about the data representation inside the neural circuit,会带给我们怎样的见解 and how it can help us on a path to understanding our own brains.以及会如何帮助我们了解自己的大脑 If you’re ready, buckle up!如果你准备好了 我们就开始吧! 阿尔特姆·基尔萨诺夫 神经流形 摘要 The brain is made up of billions of neurons,大脑由数十亿的神经元 which are electrically-excitable cells.一种电可兴奋的细胞组成 That means a neuron can generate an electrical impulse这意味着一个神经元可以对传入的刺激 in response to the incoming stimulus.产生电脉冲 The impulse then spreads along the neuron,然后冲动沿着神经元扩散 and gets transmitted onto other neurons.传输到其它神经元上 When this happens,这种情况发生时 we say that a neuron has generated an action potential,我们说一个神经元产生了动作电位 or a spike.或峰电位 Spikes are fundamental units of communication in the brain.峰电位是大脑中沟通的基本单位 All the information it receives, be it a beautiful sunset,它收到的所有信息 无论是美丽的夕阳 the smell of freshly-baked croissants,新鲜出炉的羊角面包的气味 or the notion of Pythagorean Theorem you learned back in primary school,还是小学时学到的勾股定理的概念 are all thought to be encoded in the collective behavior都是在神经元的集体行为 — the dynamics of a particular population of neurons.也就是特定的神经元群体的动态中编码的 Which exactly neurons are firing,放电的神经元 in what temporal relationship with each other these spikes occur,峰电位的所谓放电频率 and with what frequency—what’s known as the firing rate,以及出现的时间关系 all determines the content of information encoded in this seemingly chaotic activity.都决定了这种看似混乱的活动所编码的信息内容 But how exactly is information represented inside the neural circuit?但信息在神经回路中究竟是如何呈现的呢? What variables does the brain use?大脑使用了什么变量? And how they relate to the external world?它们与外部世界有怎样的关系? To begin answering questions like these,为了回答这些问题 we first need to somehow parameterize the activity of the circuit.我们首先需要将神经回路参数化 For decades scientists were able to eavesdrop on a single neuron几十年来 科学家们在神经元中 by sticking a very thin electrode inside,插入一个非常薄的电极 and measuring how the neuron’s voltage varies with time,检测神经元电压随时间的变化 和产生峰电位的时刻 and detecting when it spikes.来“窃听”单个神经元的活动 But with that technique we are able但我们只能用这种技术 to record only from a handful of neurons at a time,一次记录少数几个神经元 which is not enough,但要想解开它们集体动态的秘密 if we want to unravel the secrets of their collective dynamics.这还不够 Only with the recent advent of multi-electrode arrays直到近来多电极阵列的问世 we can now get information我们才得以 about up to a few hundred neurons in a single recording session.一次获得多达几百个神经元的信息 Knowing when each neuron produces a spike,有了每个神经元产生峰电位的时间 we obtain what’s known as the spike train.我们就能得到所谓的峰电位序列 Each vertical bar here represents the firing of the corresponding neuron,这里的每个竖条代表了相应神经元的放电 so we can read out the activity of the entire network.这样我们可以识别出整个网络的活动 We want to calculate the firing rate,我们要计算放电频率 that is, the number of spikes per unit time.也就是每单位时间内的峰电位数量 To do so, we partition the time into short panes of fixed length,为此 我们将时间划分为固定长度的短窗格 and for each pane, we count在每个窗格中 计算 how many times has a neuron spiked during that time frame.一个神经元在该时间段内有多少次峰电位 As a technical note, we usually smooth the data一个技术说明: 我们通常对数据进行平滑处理 to get a nice continuous variation instead of discrete jumps.以获得平滑的连续变化 而不是离散的突变 Thus if we have N neurons in our recording,因此如果我们的记录中有N个神经元 then at each point in time那么在每个时间点上 the activity of this population is characterized by N numbers,这些神经元的群体活动由N个数字表征 each one representing the instantaneous firing rate of the corresponding neuron.每个数字代表相应神经元的瞬时放电频率 Those N numbers form an N-dimensional vector,这N个数字构成一个N维矢量 which corresponds to a point in N-dimensional space.对应N维空间的一个点 As the time passes and the animal is随着时间的流逝 foraging or performing some other task,动物在觅食或执行其他任务时 the pattern of activity changes.活动的模式会发生变化 Some neurons increase their firing rates,一些神经元的放电频率增大 while others fire more sparsely.而另一些神经元放电频率减小 Therefore, with time,因此 随着时间的推移 this point characterizing the instantaneous activity of the network这个表征网络瞬时活动的点 will move to a new position in this empirical neural activity space.将在这个经验性的神经活动空间中移动到一个新的位置 Tracing some trajectory,问题是:所有这些点 the question is: are all of these points achievable?都是可实现的吗? Of course, since this is a biological system,当然 作为一个生物系统 there are some physiological constraints.它有一些生理上的局限性 For example, no neuron can fire with arbitrarily large frequency.例如 神经元不能以任意大的频率放电 The rate of more than 500 spikes per second is impossible由于细胞膜的特性 due to the properties of the cell membrane.放电频率不会超过每秒500个峰电位 But other than that,但除此之外 could the trajectory pass through any point in this high-dimensional space?轨迹能否经过这个高维空间的任意点? Neurons we record with multi-electrode arrays are part of the same network.我们用多电极阵列记录的神经元都处于同一网络中 They are intertwined and directly influence each other,相互交织 直接影响着对方 so their firing rates cannot be independent.所以它们的放电频率不是独立的 And the trajectory will be confined而轨迹将只局限于 to only a subspace of this N-dimensional activity space.N维活动空间的一个子空间 How this subspace looks like, as well as the exact trajectory这个子空间形态 以及确切的轨迹 would of course depend on the connectivity of the network,当然取决于网络的连接性 the strengths of the connections between the neurons, and the task itself.神经元之间的连接强度和任务本身 It has been first hypothesized,人们首先假设 and then shown many times experimentally,然后通过多次实验证明 that although the ambient space is very high-dimensional,尽管环境空间是非常高维的 the actual trajectory is confined to a very low-dimensional structure.但实际轨迹却被限制在一个非常低维的结构中 The main assumption is that我们主要假设 certain properties of the shape that the trajectory is confined to轨迹形状的某些属性 can give us insights into the mechanisms behind this particular circuit可以让我们深入了解这个特定回路背后的机制 and the nature of variables being encoded there.和所编码变量的性质 But before we see exactly what this means,但在探究这一切的意义 and how it could be done,和形成过程之前 let’s talk about the shapes in these high-dimensional spaces,我们先谈谈这些高维空间中的形状 and discuss what properties will be important to us later on.然后讨论哪些属性对我们来说很重要 什么是流形? For further investigation,为了进一步研究 we turn our attention to a very beautiful piece of mathematics—我们来看看一个非常漂亮的数学模型—— algebraic topology.代数拓扑学 It is often referred to as the geometry on a rubber sheet,它通常被称为橡胶板上的几何图形 where you are free to twist, bend, and stretch things.在那里你可以自由地进行扭转 弯曲和拉伸 That’s why to a typologist,这就是为什么对拓扑学家而言 a circle and a square is practically the same thing,圆和方实际上是一样的东西 because one can be smoothly or continuously deformed into another.因为一个可以平滑地或持续地变形为另一个 In this case we say that they are homeomorphic.这时 我们称它们是同构的 You might ask a very reasonable question:你可能会顺其自然地发问 what’s the point of such a piece of math then?这样的数学模型有什么意义呢? Wouldn’t we be saying that all the shapes in the world我们岂不是在说 are equivalent to this flexible piece of clay世上所有形状都相当于这块柔性的粘土 which we can deform into pretty much anything?我们可以将其变形为几乎任何东西? Deformation and topology have their limits:变形和拓扑学有其限制 we can’t punch holes, tear things apart, and glue them together.我们不能打洞 不能撕开 也不能粘合 That’s why a sphere is not homeomorphic to a torus.这就是球体不能与环形同构的原因 Turning one into another requires poking a hole or stitching parts together.这种变化需要戳一个洞 或将各部分缝合起来 But we are getting a little bit ahead of ourselves,但我们有点超前了 so, let’s back up.所以 回头看看 The central object will be the notion of a topological space.拓扑空间的概念是我们的核心对象 If that sounds complicated, don’t panic.如果听起来很复杂 不要惊慌 I’m sure you’re more familiar with them than you might think.我相信你比想象中更熟悉它们 In fact, you even live within one.事实上 你甚至生活在其中 Our universe is what’s known as R3, the three-dimensional(3D) Euclidean space.我们的宇宙就是R3 即三维欧几里得空间 Euclidean just refers to the way we measure distances.欧氏距离是指我们测量距离的方式 R3 means that your position is uniquely characterized by three real numbers.R3意味着你的位置由三个实数确定 You can infinitely go in any direction and nothing interesting will happen.你可以向任意方向一直走 然后无事发生 The sister space R2 is an infinite plane,同类型的空间R2则是一个无限的平面 where your position is given by two numbers, x and y.在那里 你的位置由两个数字x和y确定 Likewise, the space R is the one you’re familiar with:类似地 你应该熟悉空间R it’s just the real number line.也就是实数线 But what about R4, R5 and even RN?但R4 R5甚至RN呢? Well, since we are three-dimensional creatures,好吧 由于我们是三维生物 we can’t directly visualize higher-dimensional spaces.我们没法直接看到更高维的空间 But mathematically it’s directly analogous:但在数学上它是直接类似的: it’s just a space它只是一个 where your position is given by four or five or N real numbers,由四个 五个或N个实数确定位置的空间 like a fourth axis sticking out somewhere beyond our world.第四个轴大概伸向我们世界之外的某处 You may have noticed你可能已经注意到 that the unconstrained version of neural activity space我们在第一部分获得的 we obtained back in Part One无约束版的神经活动空间 is actually an example of RN,实际上就是RN的一个例子 where N is the number of neurons we record.其中N是我们记录的神经元数量 But if that was the whole story about topological spaces,但如果这就是拓扑空间的全部内容 things wouldn’t be really interesting.一切就没那么有趣了 Let’s see what other topological spaces exist让我们看看 除了显而易见的RN家族 other than the obvious family of RNs.还存在什么其它的拓扑空间 One very intuitive example is the surface of the sphere,球体的外表面是个非常直观的例子 which the surface of the earth we live on这和我们所居住的地球表面 can be approximated with.是类似的 Notice that if you live on the surface of the sphere,请注意 如果你处在球体表面 and you keep moving forward in any direction,并向任何方向不断前进 eventually you will reach the point where you started,最终你会回到起点 which is not the case in R2 at all.而在R2中则完全不是这样的 Other examples include distorted spheres, planes, tori, Möbius strips,其他例子包括扭曲的球体 平面 托里 莫比乌斯带 and even some more strangely-looking things.甚至还有一些看起来更奇怪的东西 All of these are what we’re going to call manifolds.我们将称所有这些面为流形 The technical definition of a manifold is a bit more abstract.流形的严格定义要更抽象一些 But for our purposes, and to develop an intuitive understanding,但为了达到我们的目的 也为了更好理解 it’s really useful to think of a manifold把流形看作是欧几里得空间中 as some shape in a Euclidean space某种局部类似于较低维度 which locally resembles a Euclidean space of a lower dimension.欧几里得空间的形状 是个很有用的办法 Let’s try to see what it means.让我们努力理解一下其中的含义 Technically we’ll live on the surface of this sphere.严格来说 我们生活在一个球体的表面 Right? A shape in three dimensions.对吗? 一个三维的形状 But in our day-to-day lives,但是在我们的日常生活中 a surface of the Earth feels an awful lot like a flat plane.地球的表面给人的感觉非常像一个平面 That’s because we are very tiny compared to the Earth itself.这是因为与地球本身相比 我们非常微小 Indeed if you zoom in close enough,事实上 如果你在飞机上足够近地观察地球 it will be indistinguishable from the plane.你将很难区分地球表面是不是球面 You may remember from calculus how,你可能记得在微积分中 if a function is smooth, or differentiable at a point,如果一个函数是平滑的 或在某一点是可微的 around that point it could be approximated with a straight line.那么这一点附近 可以用一条直线来拟合 And it’s the same idea!这个思路是相同的! In fact, the graph of a function can be thought of事实上 我们可以将一个函数的图形 as a manifold living on the plane in R2,看作一个存在于R2平面上的流形 which locally resembles a straight line, or just R.它的局部类似于一条直线 或者说R Likewise, a torus is also a manifold,同样 环也是一个流形 because it everywhere looks like a flat plane as well.因为它也能处处近似为平面 And just to give you one counter example:仅举一个反例: if we pinch the torus,如果捏住圆环 collapsing one of the circles in its cross section into a single point,将其横截面上的一个圆收缩成一个点 it would no longer be a manifold.它就不再是一个流形 Do you see why?你知道为什么吗? Because around that very point where we pinched it,因为就在我们捏住的那一点上 it no longer looks like a flat plane.它不再看起来像一个平面 No matter how close you zoom in,无论你把镜头拉得多近 things are kind of funky here.这里的情况都有点古怪 Manifolds often arise when we solve differential equations,流形经常出现在解微分方程 or, as we’ll see, analyze experimental data.或分析实验数据时 Consequently, we need some meaningful ways to parameterize the resulting manifolds,因此 我们需要一些有意义的方法来参数化产生的流形 and to analyze their properties.并分析其属性 If we continuously deform a sphere in some funny way,如果我们以某种有趣的方式连续地使一个球面变形 we’ll still get a manifold that is我们仍然会 topologically equivalent, or homeomorphic, to the sphere.得到一个与球面拓扑等价或同构的流形 And sure it’s lost all its roundness and outside symmetry,当然 它失去了所有的圆度和外部对称性 but there are some properties that stay constant, or invariant,但有些属性在这种连续变形下保持恒定 under such continuous deformations.或者说是不变的 I would like to make an emphasis我想强调 on two of such invariant properties of manifolds流形的维度和亏格 that will be important later on:是它的两个不变属性 that is the dimension and the genus.它们在之后会非常重要 Let’s start with the first one.让我们从第一个开始 [Music][音乐] We have all heard the word “dimension”,我们都听过“维度”这个词 so we are quite familiar with it.所以我们对它相当熟悉 If i ask you, “what’s the dimension of this manifold?”,如果我问你“这个流形的维度是多少?” What would you say?你会怎么回答? Well it’s sitting inside the three-dimensional space.它位于三维空间内 We can clearly see the three axes, right?我们可以清楚地看到这三条轴 对吗? But at the same time, it’s some sort of a convoluted line,但同时 它是某种曲折的线 which we know is one-dimensional.我们知道线是一维的 What’s the catch here?这里面有什么问题呢? Manifold is characterized by intrinsic and embedding dimensions.流形以内在维度和嵌入维度为特征 An embedding dimension is the dimension of the surrounding Euclidean space嵌入维度是流形所处的周围 that the manifold is sitting inside of.欧几里得空间的维度 For our squiggly line here, the embedding dimension is three.这条弯弯曲曲的线 嵌入维度是三 Or, if it were drawn on a plane,如果它被画在一个平面上 the embedding dimension would be two.嵌入维度将是二 Intrinsic dimension, however, refers to the manifold itself.而内在维度与流形本身相关 It can be thought of as the number of degrees of freedom,它就是自由度的值 or the number of continuous variables you would need或者说 如果你生活在这个流形上 to specify your location, if you lived on this manifold.指定你的位置所需要的连续变量的数量 For example, the sphere is embedded in three-dimensional space.例如 球面被嵌入三维空间中 But it is intrinsically two-dimensional, because you only need two variables,但它本质上是二维的 因为你只需要两个变量 latitude and longitude, to uniquely determine your position.即纬度和经度 就能唯一地确定你的位置 Similarly, if you lived on a torus,同样 如果你住在一个环状体上 or, a surface of a doughnut,或者 一个甜甜圈的表面 you would still need two variables:你仍然需要两个变量: one for the angle along the big circle,一个是沿大圆的角度 and one for the other angle along the smaller circle.一个是沿小圆的另一个角度 For our line here,对于我们这条线 we can associate each point with a color of a different hue.我们可以将每个点与不同色调的颜色联系起来 Then position along the line然后沿线的位置 is uniquely given by hue value,由色相值或沿色轮的角度 or the angle along the color wheel.唯一地给出 This is what I meant by saying这就是我所说的 the trajectory will be confined to a lower-dimensional structure.“轨迹将被限制在一个较低维度的结构中”的意思 Even though the ambient neural activity space is very high-dimensional,尽管环境神经活动空间的维度非常高 the neural manifold,但网络活动 where the activity of the network lives at every point in time,在神经流形上的每个时间点 is intrinsically of a much lower dimension.本质上位于一个低得多的维度 Before we move forward, let’s see why继续推进之前 让我们看看 characterizing the dimension of such a manifold could be useful.为什么表征这样一个流形的维度可能有用 You can think of a particular neural circuit你可以把一个特定的神经回路 as part of a computer program, executing a code snippet.想象成计算机程序的一部分 执行一个代码片段 It receives inputs, carries out computations, and produces an output,它接收输入信息 进行计算 并产生输出 which then either propagates further into the brain,然后要么进一步传播到大脑 or gets executed in the form of motor commands, for example.要么 举个例子 以运动指令的形式执行 To perform computations relevant to behavior,为了进行与行为有关的计算 the brain would need some way大脑需要某种方式 to encode parameters about the external world—来编码有关外部世界的参数—— declare variables, if you will, about the animal’s声明变量 例如有关动物的 position, velocity, head direction, the intensity and irritation of the incoming stimulus.位置 速度 头部方向 传入刺激的强度和刺激性的变量 Of course, we don’t know exactly how this happens当然 我们不知道这到底是如何发生的 and what’s being encoded.也不知道编码什么 But we can infer the number of independent variables being used.但我们可以推断出使用了多少自变量 Suppose we record population activity假设我们记录了负责运动 from part of the cortex which is responsible for movement,的部分皮层的群体活动 and we discover that the activity of the network我们发现该网络的活动 is confined to a two-dimensional manifold.被限制在一个二维流形内 We can postulate that this circuit cannot encode我们可以假设这个回路不能独立地 two positional variables, x and y,对两个位置变量 即x和y and two velocity parameters in an independent way,以及两个速度参数进行编码 because then the dynamics would need to be at least four-dimensional.因为那样的话 动力学至少需要四维的 Dimension is nice,维度很好 but it would be cool to have some other information但如果能有一些关于所得流形的其它信息 about the resultant manifold,就更好了 which would relate to external variables in some meaningful way.这会以某种有意思的方式与外部变量联系起来 [Music][音乐] When people talk about topology,当人们谈论拓扑学时 they are required by the sacred oath神圣的誓言要求他们 to give an example of cups and doughnuts,举出一个杯子和甜甜圈的例子 and how they are the same thing并说明它们是同一事物 since one can be deformed into another.因为一个可以变形为另一个 “Look,”, they say, “they both have a hole.”“看” 他们说 “它们都有一个洞” What had always puzzled me is一直让我感到困惑的是 why people are so obsessed about, well, holes.为什么人们对 呃 洞 如此痴迷 Oh yes, mathematically speaking,哦 是的 从数学上讲 deformations that preserve the number of holes根据定义 洞的数量恒定 are, by definition, continuous.变形是连续的 And continuity is kind of a big deal in math连续性在数学中是个大事 because it opens up a lot of possibilities.因为它带来许多可能性 But that explanation isn’t very enlightening, either.但这种解释也不是很有启发性 I would like to show you how holes reflect something so fundamental,我想告诉你 洞如何反映出一些非常基本的东西 and so intrinsic about the manifold itself它与关于流形的本质如此贴近 that it’s actually kind of creepy.以至于我都觉得有点毛骨悚然了 Imagine you lived on a torus.想象一下 你生活在一个环状体上 Just like this sphere,就像这个球体一样 locally, it looks like a flat plane everywhere.局部看来 它处处都是平面 And in the same way as with the sphere,和球体一样 if you walk forward in any direction,如果你向任何方向走 you would eventually end up in the point where you started.最终都会走到你开始的地方 Is it possible for you to distinguish如果不飞到太空中拍照 whether you live on a torus or on a sphere你能区分你是生活在环状体 without flying into space and taking a picture?还是球状体上吗? Pause and ponder about that for a minute.暂停一下 思考这个问题 I’ll give you a hint:给你个提示: you have an infinitely-long, perfectly-slippery string.假设你有一条无限长的 完美滑溜的绳子 Here’s the thing: if you take this string,事情是这样的:如果你拿着这根绳子 and ask a friend to hold one end,让一个朋友拿着一端 then you go around the world, reaching your starting point—然后你绕着世界走 到达你的起点—— but this string has now been wrapped around the planet.但这根绳子现在已经绕着地球走了一圈 You take one end from your friend,你从你的朋友那里拿起一端 while another one is in your hands,而另一端在你手中 and you try to tie a knot.你试图打一个结 Let’s see what happens in the case of a sphere.让我们看看在球体的情况下会发生什么 Since the string is slippery,由于绳子很滑 the loop can easily slide along the surface.绳子结成的圆环可以很容易地沿着表面滑动 And eventually,最终 you’ll end up with a free string with a knot on it.你会得到一根打了结的 不受束缚的绳子 If you lived on a torus, however,然而 如果你住在一个环状体上 and you happen to go through the hole,而你碰巧穿过了这个洞 then, no matter how hard you pull,那么 无论你怎么用力拉 you won’t be able to tie a knot.你都无法打结 Do you see why?你知道为什么吗? Because the string can slide along the surface,因为绳子可以沿着表面滑动 but it can’t go through,但它不能穿过 it will be wrapped around the torus forever.它将永远缠绕在环状体上 once you go through the hole,一旦你穿过了这个洞 there is no way out other than to cut the string.除了剪断绳子 就没有别的办法了 Notice, we were able to distinguish between two non-homeomorphic manifolds注意 我们不离开两个非同构流形的表面 without leaving their surfaces.就能区分它们 In fact, we couldn’t see the exact shape.事实上 我们无法看到确切的形状 It could have been a sphere, or some sort of distorted Thing-a-magic.它可能是一个球体 或者是某种扭曲的神奇的东西 It would have the same local properties.它会有相同的局部属性 From the point of view of someone who lives on the surface,对于生活在其表面的人来说 this is indistinguishable from that.各种形状都是没有区别的 We could, however, determine whether it has a hole in it.然而 我们可以确定它是否有一个洞 But what is a hole anyway?但洞到底是什么呢? It turns out holes have different dimensions as well.事实证明 洞也有不同的维度 The intuition for one-dimensional hole is like a handle.一维洞的直观感受就像一个把手 if you can put your manifold on a necklace,如果你能用你的流形串根项链 it has a one-dimensional hole.它就有一个一维的洞 Two-dimensional hole is something we would think of as a cavity.在我们看来 二维洞是一个空腔 Take this sphere for example.以这个球体为例 It has no one-dimensional holes.它没有一维的洞 But it has empty space inside, which we can fill.但它里面有我们可以填充的空心区域 if you can fill it up with toothpaste,如果你能用牙膏把它填满 it has a two-dimensional hole.它就有一个二维的孔 Unfortunately, this is where the intuitive analogy ends.不幸的是 这个直观的比喻到此为止 But there is a mathematical definition但有一个数学定义 which generalizes the notion of a hole to N dimensions.将洞的概念概括为N个维度 I won’t go into that in this video—我不会在这段视频中讨论这个问题—— just mention that it uses the same trick只是提一嘴 它使用了同样的技巧 of continuously shrinking things down into a point,把东西不断缩小成一个点 like we did with the toroidal planet example.就像我们在环形行星的例子中做的那样 The hole is something that prevents such a shrinkage.洞是防止这种收缩的东西 By now you have probably guessed现在你可能已经猜到 that we’ll be interested in the number of holes the neural manifold has.我们会对神经流形上的洞的数量感兴趣 So without further ado, let’s see a real life example.因此 不再多说 让我们看一个现实生活中的例子 [Music][音乐] The brain has a dedicated system to keep track of the head orientation,大脑有一个专门的系统来跟踪头的方向 which consists of special head direction cells.它由特殊的头部方向细胞组成 They seem to be representing the angle—它们似乎代表了 where relative to the environment you are facing,关于你所面对的环境的角度 and play a vital role in spatial navigation.并在空间导航中发挥了重要作用 These neurons have a preferred direction,这些神经元有一个偏好的方向 and signal you whether you’re facing this direction or not并通过增加放电频率向你发出 by increasing the firing rate.你是否面对这个方向的信号 Head direction system is a well-studied circuit,头部方向系统是一个经过充分研究的神经回路 but it provides a very promising route但它提供了一个非常有前景的途径 to apply the methods可以将 of analyzing the collective dynamics of a large number of neurons分析大量神经元的集体动态的方法 to uncover the true nature of latent variables being encoded.应用于揭示被编码的潜在变量的真实性质 Remember our assumptions:记住我们的假设: the information representation unfolds at the scale of the population of neurons.信息表象在神经元群体的规模上展开 So only by examining the activity of a large number of cells simultaneously因此 只有通过同时检查大量细胞的活动 we can uncover something useful.我们才能发现一些有用的东西 If the collective dynamics of the circuit如果神经回路的集体动态 encodes a variable of a certain dimension, and certain topology,编码着具有一定维度和一定拓扑结构的变量 then the activity of this network would be localized那么这个网络的活动将被定位到一个子空间 to a subspace, or, a manifold of the matching dimension and topology或者说 一个具有匹配维度和拓扑结构的流形 And so we record activity from part of the thalamus因此 我们记录丘脑上 where head direction cells are located.头部方向细胞所在部分的活动 As time goes on, we make measurements about firing of neurons随着时间的推移 我们对神经元的放电进行测量 obtaining a cloud of points in high-dimensional space.获得高维空间中的点云 Then we reconstruct the shape of this point cloud—然后我们重建这个点云的形状—— how exactly they align in space.它们在空间中的准确排列 Under the hypothesis that the neurons we are studying假设我们所研究的神经元 represent the head direction,代表头部方向 what would you expect the resulting manifold to look like?你期望得到的流形是什么样子的? [Music][音乐] Well, if the circuit truly encodes only the direction the animal’s facing,好吧 如果这条回路真的只对动物的朝向进行编码 we would first of all expect the manifold to be one-dimensional,我们首先会期望流形是一维的 because it’s one-variable.因为这是单变量问题 We’d also expect to see a hole in the middle,我们还希望在中间看到一个洞 because the variable is measuring the angle—因为变量是测量角度的 so, basically something like a loop, which is homeomorphic to a circle.所以 这基本上是一个与圆是同构的 类似于环形的东西 And this is exactly what we find—而这正是我们所发现的—— the activity of a real group of neurons在一只真正的 跑来跑去的老鼠体内 inside a real mouse just running round一群真正的神经元的活动 is localized to a one-dimensional ring,被定位在一个一维的环上 though, granted, quite a convoluted one.当然了 尽管这是个相当曲折的环 And the state of the network described而这个环上的点 by the point on this ring at every instance of time在每个时间点描述的网络状态 directly corresponds to the animal’s head direction.直接对应于动物的头部方向 That is, just by looking at the experimental data we record from the brain,也就是说 仅仅通过观察我们从大脑中记录的实验数据 and not seeing the mouse at all,而且根本不用看到老鼠 we can definitely say which direction it is facing.我们就可以肯定地说 它正朝着哪个方向 Isn’t that fascinating?这不是很迷人吗? Interestingly, equal distances along the ring有趣的是 沿环的距离相等 correspond to equal differences in the facing angle.对应的朝向角度的差异也相等 So there is a beautiful one-to-one mapping between the two.因此 两者之间有一个美丽的一一映射 To me this is just a brilliant example对我来说 这只是一个出色的例子 of how intrinsic dimension and topology of the neural activity manifold来说明神经活动流形的内在维度和拓扑结构 inform us about the structure of data being encoded inside the circuit.是如何告知我们神经回路内部正在编码的数据结构的 Topological data analysis and computational neuroscience are both very young fields,拓扑数据分析和计算神经科学都是非常年轻的领域 and they are only beginning to intertwine with each other.它们才刚刚开始相互交织 But this interaction is very, very promising on our quest但这种互作在我们探寻 to understand how information is embedded信息如何被嵌入到高维表象 into high dimensional representations,使大脑能够执行复杂任务的过程时 allowing the brain to perform complex tasks.会是个非常非常有的潜力的方法 By analyzing the geometry of neural population activity,通过分析神经群体活动的几何形状 we can gain insights into the internal workings of various brain regions:我们可以深入了解大脑各个区域的内部运作: for example, how the structure called hippocampus encodes your position in space,例如 被称为海马体的结构如何编码你在空间的位置 how motor cortex prepares and executes movement,运动皮层如何准备和执行运动 and even how the brain creates abstractions and generalizations.甚至大脑如何创造抽象和概括 And all of that is just the very beginning而所有这些只是我们面前 of this exciting journey ahead of us.这个令人兴奋的旅程的最开始 So hopefully next time you plan to因此 希望下次你打算 impress girls by talking about topology,通过谈论拓扑学来打动女孩时 you won’t be limited to coffee mugs and doughnuts.不会局限在“咖啡杯”和“甜甜圈”上 参考文献
  • 2022-06-27为什么我们会有不同的血型?I get asked all the time what my type is.总是有人问我是什么血型 A negative.A型阴性 What? It’s way more important! What if I need a blood transfusion?怎样?太重要了好吗!我如果需要输血 该咋办呢? Hey blood brothers and sisters,嗨 兄弟姐妹们 Julian here from D-NEWS from the Youtube space in LA.我是洛杉矶油管《D News》的Julian Even if you don’t know your blood type即使你不知道自己的血型 you’ve probably heard the terms thrown around before.但很可能早就听过这些术语了 AB positive. O negative. What do they mean?AB阳性 O阴性 这些是什么意思呢? It turns out there are actually 33 different systems for categorizing a person’s blood,事实上 有33种不同的系统可以对一个人的血液进行分类 but the nomenclature you’re most familiar with is a combination of two of them:但大家最熟悉的命名法是其中两种的组合: the ABO system and the Rh system.ABO血型系统和Rh血型系统 The reason these two are so much more well known这两种血型系统之所以广为人知 is because they are by and large the most important factors in blood transfusions.是因为 它们基本上就是输血的最重要因素 In most cases these alone should be enough for a doctor to know多数情况下 仅这两种系统就足以让医生知道 what kind of blood to pump back into you if you’ve sprung a leak.当你失血时 该给你输什么血 It’s why some racing drivers in the ‘70s and ‘80s这就是为什么70至80年代的一些赛车手 had their blood type sewn on their race suit or painted on their car.把他们的血型缝在赛车服上或漆在车上 Nowadays they don’t bother,现在 不用麻烦了 the tests to determine blood types and compatibility with donor blood确定血型 和与献血者血液相容性的测试 are quick and much more foolproof than relying on embroidery or a sticker.速度很快 且比依靠把血型缝在衣服上或贴在车上更可靠 So what do the letters and plus/minus symbols actually denote?那血型字母和±符号到底是啥意思呢? They’re describing little surface markers on the blood cells它们描述的是 血细胞表面的一些小标记物 called antibody generators, or antigens for short.名为抗体生成器 或简称为抗原 Antigens come in a lot of different varieties抗原有很多不同种类 and your body’s immune system attacks cells with antigens that don’t match your own.而人体免疫系统会攻击携带异种抗原的细胞 Having the right antigens is a little like找到合适的抗原有点像是 knowing the password to get into the super secret, boys-only treehouse.知道了进入男孩子专属绝密树屋的暗号 Antigens can be either proteins or sugars.抗原可以是蛋白质或者糖 The antigens described by the ABO blood group system are sugarsABO血型系统描述的抗原是糖 and they come in 4 different combinations or “types”.该抗原有4种不同的组合或“类型” Type O means the blood cells have no A or B antigens,O型意味着血细胞没有A抗原或B抗原 so it might be easier to think of it as type zero.所以把它看成零型 可能更易于理解 People with this blood type can only receive type OO型血的人只能接受O型血 because their immune systems will attack anything with an A or B antigen.因为他们的免疫系统会攻击任何携带A或B抗原的物质 But any other blood type can accept type O blood但是其他血型都能接受O型血 because the red blood cells will be ignored by the immune system.因为免疫系统会忽略其红细胞 Type A means cells have the A antigen so they can’t receive type B blood,A型血意味着细胞有A抗原 所以不能接受B型血 and type B means cells have the B antigen and won’t be compatible with type A blood.B型血意味着细胞有B抗原 因此无法与A型血相容 I think you see where this is going:我想你们已经猜到了: type AB means the red blood cells have both A and B antigens,AB型血意味着红细胞既有A抗原 也有B抗原 and so none of the white blood cells will attack anything with A or B antigens.因此 白细胞不会攻击任何携带A或B抗原的物质 People with this blood type can accept any old human blood.AB型血的人 可以接受任何人的血 Well, so long as the Rh antigens are correct too.当然了 只要Rh抗原也能匹配 The Rh blood group system is so namedRh血型系统之所以这样命名 because 75 years ago it was discovered the antigens是因为 75年前人们发现这些抗原的表现 behaved similarly to those in Rhesus macaques.与恒河猴身上的抗原表现类似 But they ARE different! So don’t go around just injecting monkey blood all willy-nilly.但它们不一样!所以不要到处去随意注射猴血 Rh antigens are proteins, there are 49 varietiesRh抗原是蛋白质 有49种 but one in particular, RhD, is highly immunogenic,其中一种 RhD的免疫原性格外的强 meaning immune systems that don’t have it freak out when they encounter it.意味着 当不含RhD的免疫系统与其相遇时 会产生强烈反应 So if you have RhD, your blood type has a plus symbol next to it所以 如果你是RhD型血 血型旁边有加号 and you can only donate to other positive blood types,你就只能给其他RhD阳性血型的人献血 but you can accept positive and negative blood types.但你可以接受RhD阳性和阴性血型 Put the two systems together and it means O-negative is the universal donor,把这两个系统合起来 意味着O-是万能输血血型 while AB+ will be the universal receiver.而AB+则是万能受血血型 Blood types are passed down through your genes.血型会通过基因遗传 You can change blood type, but it’s extremely rare.也可能会发生改变 但极为罕见 It either happens from some sort of illness,要么是某种疾病所致 or if you get a bone marrow transplant,要么是你做了骨髓移植 your blood will eventually convert to your donor’s type.那你的血型最终会变得跟捐赠者的一样 So now you know! Unless you have some rare blood type现在你懂了吧! 除非你是罕见血型 that needs one of the other 31 blood group systems to describe it,才需要另外31种血型系统来鉴别 you now understand what the letters and symbols of your blood type mean.现在 你明白自己血型的字母还有符号的含义了吧 In some places like Japan,在一些地方 如日本 it’s believed that blood types also correspond to personality traits,人们相信血型与性格特征相对应 but really it only affects your immune system.但事实上 血型只会影响你的免疫系统 Thinking Type O blood makes a person confident and controlled认为O型血使人自信自律 is kind of like thinking Jupiter is going to affect your luck today.就像认为木星能影响你今天的运气一样 Speaking of, here’s Laci talking about why Astrology is silly.说到这里 Laci正在讲述为什么占星术是无稽之谈 Check the description for a link if you’re on your mobile.如果你是移动端 查看简介里的链接 Astrology can’t be proven wrong and that’s the heart of what science is.占星术并无法被证实是错的 而印证正是科学的核心所在 The assertions of astrology are so general and open to interpretation占星术的断言如此笼统 从哪方面都说得通 that we can always find a way to see it in a factual light.以至于我们总能从现实中找到角度去解释它 Are there any other things like blood types you take for granted还有没有其他像血型这样的 只因你从未思考 because you just never thought about it?就觉得理所当然的事情呢? What if you want us to explain them, go ahead and ask us in the comments,如果你想听我们的解释 请在评论区留言 it’s what we’re here for.这就是我们的初衷 I’ll see you next time on D-NEWS.我们下期《D News》见
  • 2022-06-27打破关于新陈代谢的迷思“Green tea boosts your metabolism.”“绿茶能加速新陈代谢” “Don’t eat after 7 pm.”“晚7点后不能吃东西” “Work out on an empty stomach.”“空腹锻炼” We are surrounded by myths谈到机体如何消耗能量 when it comes to talking about the way our bodies burn energy.我们身边从来不缺各种奇谈怪论 Another common one is that your metabolism is doomed to go downhill after you become an adult.另一常见说法是成人后新陈代谢必然下降 But the good news is that might not actually be true.不过好消息是 这不一定是事实 Every minute of every day,机体每时每刻都在 your body is converting food or stored fat into energy to keep itself going,将食物与存储的脂肪转化为能量来维持自身运转 doing things like pumping blood, expanding and contracting your lungs,维持泵血 肺部收缩扩张 plus all kinds of stuff on a cellular level,和所有细胞层面的活动 like making new cells and getting rid of old ones.比如生成新细胞并清除衰老细胞 This is your basal metabolic rate.这就是你的基础代谢率 On top of that, there’s the energy you expend除此之外 还包括了你的 to move around and do the physical activity of your day…自身活动 日常体力劳动 plus the energy it takes to process your food into energy in the first place.加上消化吸收食物所消耗的能量 The exact amount of energy it takes to do all this varies from person to person.以上活动具体需要消耗多少能量 则因人而异 If someone burns through a lot of energy in a given amount of time,若一个人在特定时间内能消耗很多能量 we say they have a fast metabolism.我们就说他新陈代谢很快 Those who burn less energy in the same amount of time have a slow metabolism.同样时间内消耗能量较少的人新陈代谢慢 There are so many crash diets and quick fixes有很多快速减肥饮食和速效减肥方案 that promise to speed up your metabolism to help you achieve weight loss,声称可通过提高新陈代谢来达到减重目的 but the truth is that the speed of your metabolism is determined almost entirely by your genes.但事实上新陈代谢速度基本完全由基因决定 And research is also telling us that我们通过研究得知 metabolism actually plays a relatively small role in weight management anyway,事实上 新陈代谢对于体重的影响较小 the biggest factors for this are good ol’ diet and exercise.影响最大的因素是健康的饮食和锻炼 So how about that “our metabolism gets slower as we age” factoid?那么你对“新陈代谢随年龄而下降”的说法怎么看呢? Well, for years it was widely accepted by the scientific community,很多年里科学界居然普遍认同这一观点 but a 2021 study has given us a much-needed update.但2021年有项研究提出了我们急需的最新成果 A team of 80 co-authors have analyzed metabolic rate data一个包含80名合著者的团队研究了 collected by different labs over the course of 40 years.来自众多实验室长达40年的新陈代谢率数据 This data comes from more than 6,400 people数据来自6400多人 ranging from 8 days old to 95 years old.年龄在8天到95岁之间 Turns out, there are metabolic shifts in our lives,从中发现人的一生中确实会发生新陈代谢率变化 just probably not when you think.只是可能不是你想象的那样 Our calorie-burning peak is actually when we’re infants,实际上我们消耗能量的巅峰在婴儿期 when from birth to 15 months从出生到15个月这期间 we’re using crazy amounts of energy to grow our brains and our bodies.我们消耗大量能量供给大脑和机体发育 Infants actually burn calories 50% faster than adults!事实上婴儿消耗能量的速度比成人快50% After these early days,这一时期过后 our metabolism slows down throughout childhood and adolescence儿童和青少年时期新陈代谢有所放缓 before it settles around age 20 into our adult rate.直到20岁左右进入成年期才会稳定下来 Then at 60 years old, our metabolic rate drops again,到60岁时新陈代谢再次下降 and keeps declining until the end of our lives. 并持续下降直到生命结束 But between 20 and 60, that big span of time in the middle但在20到60岁这个大跨度生命中期 our metabolism stays pretty much the same, 哪怕经历怀孕或更年期的巨大生理变化 even through big changes like pregnancy or menopause.新陈代谢也基本保持不变 Your metabolism may be different from someone else’s, 你的新陈代谢可能与他人不同 but it’ll be pretty much the same throughout your adulthood.但在整个成年期内它基本保持不变 That means that when we do see weight changes as we age,所以当我们发现体重随年龄改变时 it’s likely not due to metabolic shifts directly, 新陈代谢可能不是直接原因 but the countless other things that can affect the way our body stores energy,压力 睡眠质量 基因 服药情况 饮食等很多其它因素 stuff like stress, sleep quality, genes, medications, diet and so much more.反而是影响机体储存能量方式的主要因素 While this new data can help us新的研究数据帮助我们 cut through the crap of ‘magic metabolism boosting pills’摒弃无用的“神奇的促新陈代谢药物” or blaming weight gain on middle age,以及“中年人新陈代谢下降导致增重”的谬论 it also lays the groundwork for some really cool medicine.也同时为一些很棒的药物研究铺垫了基础 Now that we know about the metabolic decline after 60, we can look into specialized ways如今已知60岁后新陈代谢会下降 我们可以 of prescribing medication that takes metabolic decline into account.基于新陈代谢下降的情况有针对性地开处方药 The other end of the age spectrum may hold some answers too,年龄谱另一端的人也有所收获 like early life metabolic rates could tell us幼年时期的新陈代谢率揭示了 what an infant’s weight gain might mean for their health as an adult.婴儿体重增长对其成年后的健康意味着什么 Research like this could hold the keys这类研究也是解决肥胖 to tackling health issues like obesity and malnutrition too.和营养不良这类健康问题的关键 And because metabolism is really a process at the cellular level,由于新陈代谢本质上是细胞层面的过程 if stuff goes wrong here it can result in issues like cancer.若出了问题可能导致癌症等疾病 So knowing more about how all of this works throughout someone’s life所以 深入了解新陈代谢在一生中的变化规律 is about so much more than just weight.带给我们的可不只是体重上的改变 This study offered us many data points,这项研究为我们提供了很多数据点 but each from a different person at a different point in their own life.但分别来自不同个体的不同生命时期 The next steps could be to follow the same person over time.接下来我们要对同一个人进行跟踪观察 Doing this with multiple people, over long periods of time,长期在多个人身上重复实验 is a really difficult research endeavor, so you can see 确实是一项艰难的研究任务 由此便知 why we don’t have a lot of clear data in this area yet.为何这个领域我们还未获得大量翔实数据 It gets more complex when researchers want to take an 当研究人员想对诸如特定基因的表达 even closer look to like the activity of specific genes,免疫系统 甚至肠道微生物构成等因素 the immune system, even gut microbiome composition进行更进一步观察并把这些变量合并研究 and bringing all these variables together.研究就会变得更加复杂 Why it stays steady, 新陈代谢为何保持稳定 what’s happening in those periods of growth spurt and decline at the bookends of our lives, 生长激增期和末期衰退时发生了什么 how and why metabolism differs so much 为什么人与人之间新陈代谢相差甚远 from individual to individual, 而这又是如何造成的 these are the questions that we’ll hopefully get some answers soon这些问题我们有望在不久的将来得到答案 and get us closer to our healthiest selves.并使我们有能力更进一步追求自身健康 So… how do our bodies actually transform food into energy?所以……想知道食物如何被机体转化为能量? You can check out our Human episode all about that here.请观看我们《人类》选集中相关内容 And if there’s another health science topic you want us to cover,若有其它想听我们聊的健康科学话题 let us know in the comments.请在评论区告诉我们 Don’t forget to subscribe, thanks so much for watching别忘了订阅哦 感谢观看 and I’ll see you next time on Seeker.期待下次和你在《探索新闻台》见面
  • 2022-06-27超越光速Imagine a galaxy and its light took 25,000 years to get to us.设想某个星系发出的光要经过两万五千年才能到达地球 How far away is that galaxy?那这个星系离我们有多远? Euh…25,000 light years away.呃……两万五千光年那么远吧 Beautiful!很棒! Now, imagine a galaxy现在 设想有一个星系 and it took the light 13.4 billion years for the light to get to us.它发出的光要经过134亿年才能到达地球 How far away do you think that galaxy is?你认为这个星系离我们有多远? I’d imagine it’s 13.4 billion light years away.我想它有134亿光年那么远吧 The answer is actually 32 billion light years.实际上答案是320亿光年 How does that work? Wait.这怎么可能?等一下 Yes!就是这样! I got the first one, right?我第一个问题答对了 是吧? There is a galaxy that we actually discovered in 2016,我们在2016年确实发现了一个星系 it’s called GN-z11.叫做GN-z11星系 It took about 13.4 billion years for that light to get to us.它发出的光要经过约134亿年才能到达地球 But the galaxy right now is 32 billion light years away.但是现在这个星系距我们320亿光年远 How was that possible?这怎么可能呢? I don’t know, my brain’s already broken.不知道 我脑子已经不转了 带上编辑去远足之 复杂事件探秘(太空篇) The universe is just like this stagnant thing.宇宙就像静止的物体一样 You know, like all these rocks are where they are,你看 就像这些石头一样纹丝不动 and light is emitted from that rock光是这边的石头发出来的 all the way over to this rock.然后照射到另一边的石头上 If nothing moved, and it took 13.4 billion years如果它们都保持不动 光需要经过134亿年 for the light to get across from one to the other.才能从一块石头照到另一块 Then they would be 13.4 billion light years apart.那它们之间的距离就应该是134亿光年 But imagine the space between all the rocks and dirt—但是想象一下这些石头和尘土之间的空间 imagine that’s all expanding with the rocks.如果这些空间和石头一起不断膨胀 So as light travelling across,那么 当光线穿过它们时 the distance between the rocks is getting bigger and bigger.石头之间的距离就会随之越来越大 So even though, it only took 13.4 billion years因此即使GN-z11的光只需要134亿年 for the light to get from GN-z11 to us,就能到达地球 we are now 32 billion lightyears away from that galaxy.但现在地球距这个星系却有320亿光年 The universe expanded in that time.因为宇宙在此期间膨胀了 Yeah, I think it’s one of the most unintuitive things about the universe.是啊 我觉得这是关于宇宙的最难理解的事情之一 Space itself can expand.宇宙自身会膨胀 When I first learned that the universe is 13.8 billion years old,当我第一次得知宇宙已经138亿岁了 so the edge of it should be 13.8 billion lightyears away.我以为它的边界也应是在138亿光年处 So that’s how we always talked about distance when we talk about light years.我们谈及光年时 总是会这样推测距离 But it’s not, it’s 46 and a half billion lightyears away.但并非如此 宇宙边界实际有465亿光年远 I have to call myself out here,我得跳出这个旧思维 because when I talk about the size of the universe,因为当我谈到宇宙大小时 what I meant was the size of the observable universe,我指的是可见宇宙 即到目前为止 which is the sphere of stuff that we have been able to see so far,那些由于光有足够的时间到达地球 because light has had enough time to get to us.从而能被我们观察到的物质 所构成的球体的大小 Our observable universe is growing.我们的可见宇宙在变大 We don’t know how big the universe is.我们不知道宇宙实际上有多大 We don’t even know if it has size.我们甚至不知道它是否有边界 Any way, the observable universe is a lot bigger than I thought.无论如何 可见宇宙比我想象中大得多 I was so confused.我曾经很困惑 How is it possible for the univese to be so much bigger宇宙怎么会如此之大 than light has had time to get to us?让光都来不及到达我们这里呢? That concept to me is so confusing and mind bending.这个概念一直令我疑惑不解 But it comes because all of space is expanding and streching in the entire universe.但这是因为整个宇宙中的所有空间都在膨胀和拉伸 Space is not this stagnant thing.和我们之前看到的石头不一样 It’s not like this field of rocks.宇宙空间并不是静止的 All of this space-time is spreading apart.时空在不断延展 There is more and more space being created越来越多的空间正在产生 and the effects of that is that space is expanding with galaxies其结果是空间随着星系的扩大而扩大 and carrying them apart from each other.而且星系之间也越离越远 You start to notice that galaxies are actually receding away from us.你开始意识到 星系实际上正在远离我们 So the futher away they are, the faster they are moving away from us.它们离我们越远 远离的速度也就越快 Something that’s a megaparsec away from us一个距离我们百万秒差距的物体 is moving at 70km/s away.会以70km/s的速度远离 Something that is twice that,两倍来算 so 2 MPC is moving at 140 kilometers.两百万秒差距的物体会以140km/s的速度运动 You can keep going eventually until you get to 299 thousands km/s.你可以继续算下去 直到速度到达299000 km/s Do you know what that speed is?你知道这是个什么速度吗? As the speed of light?和光速一样吗? Yes, yeah, it’s the speed of light.没错 就是光速 So eventually you get to that speed,你把最终得到的这个速度 and you plug into your equation,代入到你的等式中 and you get that the distances away from us to a galaxy你会得到一个以光速远离地球的星系 that’s moving from us at the speed of light和地球之间的距离 is about 14 bilion light years away.大约是140亿光年 And that is far within the boundary of the edge of our universe.然而这离我们的宇宙边界还十分遥远 Here’s us. We’re…you know where we are,我们在这里 我们……你知道的 at the center of our observable universe.我们在可见宇宙的中心 And then if you go in all directions out 14 billion lightyears,如果你从中心向所有方向运动140亿光年 you get a sphere and that sphere is called the Hubble Sphere.会形成一个球体 叫做哈勃球 Beyond which, everthing is moving away from us faster than the speed of light.在哈勃球之外 一切都在超光速远离我们 And it’s not a little bit of stuff,这不只是一小部分 it is 97% of all galaxies in the universe宇宙中97%的星系 are moving away from us faster than the speed of light.而绝不仅仅是几个 It’s not just a couple.都在以超光速远离我们 It’s crazy.太疯狂了 I am just trying to process it, honestly.说实话 我只是在努力还原这个过程 即将播出…… Here’s the question.我有个问题 Do you think that we can see things你认为我们能看到那些 that are moving away from us faster than the speed of light?超光速远离我们的物体吗? Well, now that you said it,呃 既然你这么问 it doesn’t sound like we could, or will ever be able to, right?听起来我们现在或将来都看不到 是吧? 即将播出…… Before we learn how things can move faster than the speed of light,在我们了解物体如何超光速运动之前 I want to share the sponsor of this video: 3M我想先介绍本视频的赞助商:3M and also my masterpiece.还有我的杰作 Turn off the lights, we’re gonna turn on the flashlight on and take picture again.关上灯 我们打开手电筒再拍张照片 It is so bright, ah!它好闪 啊! This is made with 3M’s retroreflective tape.这是用3M的反光胶带制作的 How they work totally surprised me.它们的作用原理令我大吃一惊 If you look closely to the material,如果你仔细观察这个材料 there’re these microscopic beads with perfect reflection angles上面这些微小的珠子有完美的反射角 so that more light reflects directly back the direction it came.能让更多的光线直接原路反射回去 3M is a poineer in developing the science behind retroreflection,3M公司是研发反光相关科技的先驱 and has been advancing the technology in new在过去80年里 它一直以新的 and ground-breaking ways for 80 years.突破性的方式发展技术 Their products keep you safer by making you more visible他们的产品在任何天气 条件 环境 in any kind of weather or condition, situation都能提高可视性 从而保证你的安全 like running at night, which I like to do比如我喜欢的 在晚上跑步 and it looks kind of rainbowy sometimes.而且它有时候看起来五彩斑斓 Oh, that’s so cool!哇 这也太酷了! That’s because its little glass beads are like little raindrops.这是因为它的小玻璃珠就像小雨滴一样 You probably have a 3M product 无论你在哪 房间里大概都有 within arm’s reach in your room wherever you are.触手可及的3M产品 You know I think that science is amazing.你知道 我觉得科学很神奇 But the people who take it and are super creative但那些理解了科学原理 又极有创造力 and make technology, that’s where the butters at.并创造出新技术的人 才是最优秀的 As a company, their mission is improving lives with science,作为一家公司 3M的使命是用科学改善生活 which is why they want to inspire the next generation of STEM innovators.这也是他们想要激励下一代科技创新者的原因 So, every October 3M’s Young Scientist Challenge因此每年十月的3M青年科学家挑战赛 allows students to meet their superheroes,让学生能见到他们的超级英雄 and work with 3M mentors还能和3M导师合作 to turn their ideas into reality.把他们的想法变为现实 The finalists of this challenge are being announced in a few days,这次挑战赛的入围选手将在几天后公布 but they hold the challenge every October.但他们每年十月都会举行这个比赛 So maybe you know someone who can participate.也许你能让亲朋好友来参赛 Alright, thank you so much to 3M for supporting Physics Girl.好了 很感谢3M对《物理女孩》的支持 And now back to me explaning to Levi how things can move faster than the speed of light.现在回到我向Levi解释物体如何超光速运动的部分 Slide transition.切场景 That’s good.很棒 Yeah, how is it possible that something is moving faster than the speed of light, 好 如果光速是宇宙中最快的速度 if the speed of light is the fastest thing in the universe?一个物体怎么会运动得比光速快呢? The fastest thing, like the ultimate speed limit? 最快的速度 类似终极速度限制? The universal speed limit?宇宙速度限制? What you’re referencing is Einstein’s Special Theory of Relativity,你参考的是爱因斯坦的狭义相对论 which says that nothing can move through the universe, through space即任何物体都不能在宇宙中 在空间中 faster than the speed of light.以超过光速的速度运动 And that’s true.这是对的 But space itself can expand,但是空间自身会膨胀 and the space between two objects can expand两个物体之间的空间也会膨胀 such that moves those objects apart faster than the speed of light.所以这些物体能以超过光速的速度分开 So nothing is actually voilating Special Relativity.这实际上并不违背狭义相对论 Nothing is moving through space faster than the speed of light.没有任何物体在空间中运动得比光速快 Here’s a question. Do you think that we can see things有个问题 你认为我们能看到 that are moving away from us faster than the speed of light?那些超光速远离我们的物体吗? Well, now that you said it.既然你这么问了 It doesn’t sound like we could or will ever be able to, right?听起来我们现在或将来都看不到 对吧? If something moves faster than the speed of light如果物体运动得比光速快 we will never see it via lights.我们将无法通过光看见它 Good guess. I mean that’s like, what you would intuitively think guess.猜得不错 我觉得这像是你靠直觉猜的 We’ll never see that galaxy as it is.我们永远看不到那个星系真正的样子 We’ll only see it for how it was when the emitted light left it.能看到的只是发出的光刚离开它时的样子 So what you are saying is like, you could imagine getting light from a distant galaxy就是说 你能想象你看到了很久以前 that the light was emitted like far in the past,一个遥远的星系发出的光 when things were a lot closer together,那时候它离我们更近 and then now we’re seeing that light,我们现在看到的就是那时的光 but we will never see those galaxies as they are now.但我们永远无法实时看到那些星系的样子 Okay, you are right and wrong.好的 你对了一半也错了一半 Cool! Glad it, glad it can.真棒!能对一半真开心 So, ok, that galaxy we’ve talked about at the beginning, GN-z11.好的 我们回到刚开始说的GN-z11星系 That galaxy is about 31.96 billion lightyears away from us now.它现在距离我们约有319.6亿光年 So that galaxy is moving away from us like,所以那个星系正在 three times the speed of light or something like that.以三倍光速远离我们 But you’re right. We are seeing it但你对了一部分 as it was 30.4 billion years ago.我们看见的是它304亿年前的样子 Now it may not even be there anymore,现在它甚至可能已经不在了 like all the stars might have burned out就像所有恒星 and might have been swallowed by another galaxy.可能都已经毁灭或被别的星系吞噬了 It’s crazy that I think that there’s a galaxy we’re seeing that我们现在看到的星系 might not even be in existence anymore.甚至可能已不复存在 No…That’s crazy.哦不……太不可思议了 So you’re right. There’re some galaxies that are所以你说对了 有些星系 space expanding them away from us fast enough所处的空间膨胀 远离我们的速度足够快 that we’ll never see them as there right now.所以我们永远无法实时看到它们的样子 But…there are some galaxies that are outside of our Hubble Sphere.然而……还有一些星系存在于哈勃球之外 So we mean that they’re moving away from us faster than the speed of light.意思是那些星系以超光速远离我们 But we will be able to see them as they’re now.但将来我们能看到它们现在的样子 So they are emitting light now and it will get to us.它们现在发出的光将在未来照到地球 This is crazy! You look confused.这真不可思议!你看起来很懵 You should be…you’re correct!你应该是……你是对的! It’s…OK…the galaxy is moving away from us faster than the speed of light.好……这个星系正在超光速远离我们 It emits light at us.它发出的光照向我们 And initially that…that light moves away from us.但是最初……那个光是在远离我们的 But it’s traveling through space,但它会在太空中穿行 until it gets inside of our Hubble Sphere.直到到达我们的哈勃球内部 And it’s no longer moving away from us.这时候它就不再远离我们了 Euh..let me draw it.呃……我来画一下吧 Here’s us,这是我们 and then here’s like shells of distance away from us.这是和我们距离相同的点构成的一层层壳 So imagine like this is the Hubble Sphere.假设这个是哈勃球 So this galaxy is moving away from us faster than the speed of light,那么这里的星系由于宇宙的扩张 because of the expansion of universe.正在以超光速远离我们 It emits light toward us which initially…它朝我们发光 这个光最初…… you know, because the light was emitted from this object going faster than the speed of light.你看 因为光由这个超光速运动的物体发出 It’s gonna be moving away from us.它会远离我们 So the lights moving away, but it’s making its way slowly.所以光在远离我们 但是速度很慢 This way even though this part is moving away from us.这样 虽然这部分在远离我们 It’s making its way slowly and eventually,但它行进的速度很慢 it’s gonna get to distances that are… think about it like this.但最终它的距离会达到……你这样想 So, remember how I talked about how consecutive distances还记得我说过的连续距离吗? or distances that are further and further away from us are moving faster and faster.就是越来越远的距离 会远离得越来越快 So, this right here, say moving…I don’t know,这里的这个 可能移动了……我不确定 10. This distance may means 20.10光年吧 这边距离可能代表20光年 So as the light goes this way,当光线通过这里时 now it’s going into space that moving less and less fast away from us.就进入了这个以越来越慢的速度远离我们的地方 Because the expansion rate of the universe由于宇宙膨胀速率 or the Hubble parameter is slowing down,又称为哈勃参数 正在变慢 which means that the stuff that’s now at that first circle意味着第一个圆圈里的东西 is not moving away from us as fast as the stuff that was there.和圈外的东西远离我们的速度并不相同 Does that make sense?有道理吗? The light does this crazy path光沿着这条疯狂的路径 where most like a boomerang is like it goes forward…ignore this.像回旋镖一样前进……忽略这些 Light emitted here goes forward away from us这里发出的光向前远离我们 and then comes back toward us, and eventually gets to us.又朝着我们返回 最终照到我们这里 -Does that make sense? -Yeah.-我说的有道理吗? -有 No, it doesn’t make sense. But it could.不 没道理 但它能做到 [Laughter][笑声] So as light gets closer to us,所以当光靠近我们时 it starts moving faster and faster relative to us.它相对于我们的运动速度就越来越快 There are galaxies that are outside of what we call the Event Horizon—有些星系在我们称之为事件视界 The Cosmic Event Horizonan —it’s on the outside of that.或者叫宇宙视界 的外部 All the galaxies and stars outside of that will never be able to contact them.我们接触不到视界外的所有星系和恒星 They’ll never be able to send light to us.它们发出的光也照不到我们 And is the Hubble Sphere the edge of the Event Horizon?那视界的边缘就是哈勃球吗? No. Those are actually two different things.不 它们是两回事 The Hubble Sphere is, inside that everything is moving less than the speed of light.哈勃球内是一切都运动得比光速慢的物质 Event Horizon is everything that we can see.事件视界是我们所能看到的范围 There’s actually a boundary between those two.实际上这两者之间有一个界限 It’s like a shell between those two.就像是它们中间有一段空壳似的区域 Stuff that’s moving away from us faster than the speed of light…那些正在超光速远离我们 But the light being emitted from those things now will eventually get to us.但发出的光能最终能够照射到我们的物质 That’s what’s inside that shell.就是这个壳儿里的物质 It’s like a magical shell,它就像一个魔法壳儿 and our Hubble Sphere is also expanding.而我们的哈勃球也在膨胀 More light is coming inside our Sphere of things哈勃球里的物质在超光速远离我们 that are moving away from us faster than the speed of light.而更多的光正在进入哈勃球 Because the universe is expanding.因为宇宙在不断扩张 But since universe is expanding,但正因为宇宙在膨胀 then light can be emitted from a galaxy initially…然后光最初可以从一个星系发出…… This is so nuts.这太扯了 But the light will move away from us to star and then eventually stop,但光会远离我们 照向恒星 最终停下来 and then start coming toward us.然后又照向我们这里 Relative to us, which seems like that’s violating Relativity.以我们为参照 光的运动似乎违背了相对论 But it’s not, because it’s moving through space, still at the speed of light.然而并非如此 因为它始终以光速在空间中运动 Because space is expanding.只是因为空间在膨胀 Do objects get bigger when the universe expands?当宇宙膨胀时里面的物体会变大吗? Haha… Good question.哈哈……好问题 Emm…Objects do not get bigger…No…Actually.嗯……物体不会变大的……实际上不会 So things can be easily push and pull through space.物体在空间中能够很轻易地被来回推拉 It’s almost like they have…like space has no friction.就像……其中没有摩擦力一样 I can easily pull you toward me.我能轻松地把你拉向我 I want…because I like this camera.我想这么做……因为我喜欢这个相机 Like I’m overcoming…I don’t know…Space.就像我克服了……怎么说呢……空间 So easily.如此轻易就克服了 Gravity overcomes the expansion of space,除非你达到了大概一亿光年外的地方 up until you get to something like 100 million light years.否则重力会把空间的膨胀克服掉 So little local clusters of galaxies所以只有极少的局部星团 are not really affected by the expansion of space.能够真正不受空间膨胀的影响 I mean…yeah…things are in space,我是说……物体在空间中 and then space expands and moves and the things go with it.空间会膨胀和运动 物体会跟着膨胀和运动 But that’s not true if there’s something else there to overcome但如果还有其他需要克服的力存在 that movement.可能也就不会这样了
  • 2022-06-27一抔净土掩风流,人死后还能体面吗?Yes, partially decayed zombies are gross.是的 部分腐烂的尸体很恶心 But what really happens to this beautiful specimen of human meat但是鲜活的人体死亡后 after it dies?究竟会发生什么? Let’s get into the gross details!让我们来看看到底有多恶心 Hey everybody! Trace here for D NEWs. 大家好 我是Trace 欢迎收看《D新闻》 Death is as natural as birth,死亡和出生一样自然 but it celebrated a lot less.但很少有人庆祝死亡 At the moment of death,在死亡的瞬间 the brain has a surge of activity as its last oxygen is depleted由于最后的氧气被耗尽 大脑活动激增 and it then goes dark.之后才会归于沉寂 Hormones which regulate body functions stop being secreted by the brain,大脑不再分泌调节身体机能的激素 and though some physical functions continue for a few minutes,虽然某些生理机能仍会持续几分钟 eventually all human functions stop但最终所有的人体机能都会停止 and the post-death process begins.死亡后的过程就开始了 Firstly, at death, all your muscles relax.死亡初期 你的全部肌肉会放松 It takes burning oxygen for energy to keep you tense.因为肌肉通过消耗氧气产生的能量来保持张力 No O2, no tension.没有氧气肌肉就会松弛 This includes the body’s sphincters,包括身体的括约肌 which is why death often causes defecation and incontinence.所以死亡经常会导致大小便失禁 Now, just because the body is medically DEAD,此时从医学上看身体已经死亡 doesn’t mean everything in the body is.但并不意味着身体里的一切都死亡了 Some cells continue burning remaining energy,一些细胞继续燃烧剩余的能量 which contributes to what happens after we die.这导致死后一系列身体变化 Not to mention the 100 trillion bacteria living inside of our intestines,更不用说生活在我们肠道内 皮肤上 on our skin and elsewhere.和其他部分的100万亿个细菌 They’ve been with us our whole lives…它们伴随我们一生 so there’s no reason for them to stop now.所以没有理由让它们现在就死掉 Algor mortis, or the death chill, begins immediately at death.尸冷在死亡的瞬间就开始了 On average, a human body loses 1.5 degrees (.83 C) an hour平均而言 尸体温度每小时会降低0.83℃ until it reaches room temperature.直至与室温相同 Without a heartbeat,没有了心跳 blood and fluids begin the lividity process at that point,由于重力作用 血液会流向身体最低点 succumbing to gravity, and pooling the blood at the lowest points in the body.此时 血液和体液会让尸体开始出现尸斑 In light-skinned people, 对于浅肤色的人来说 pooling blood is visible outside the body as a dark purplish-blue,体表处可以看到呈暗紫蓝色的淤积血液 and after two hours that blood clots!两个小时后血液会凝结成块 This is how forensic specialists can tell if a body has been moved.法医可以由此推断出尸体是否被移动过 Within three to six hours,三到六小时内 rigor mortis sets in, tensing the muscles again.尸僵出现 肌肉再次绷紧 After death, calcium floods the muscles tissue,人死后 钙会充斥肌肉组织 and bonds with proteins that control muscle contraction.并与控制肌肉收缩的蛋白质结合 This uncontrolled bonding causes muscles这一不受控制的结合过程会导致 to tense up for about 24-to-48 hours肌肉绷紧约24到48小时 until they wears off.直至肌肉萎缩 The eyes will cloud during this time as well, 与此同时 瞳孔变浑浊 especially if they’re left open.尤其是死时眼睛是睁开的 And once rigor sets in, they’re pretty much stuck open for a while.一旦出现尸僵 眼睛就会持续睁开一段时间 So that whole closing eyes in the movies,像电影中完全紧闭双眼也是可能的 It’s possible as long as you get to them real quickly.只要你尽快把它们合上 Though you might not have to,不过你不必为死者合眼 because according to one study,因为一项调查显示 63 percent of people fully closed their eyes at death!63%的人在死亡时会完全闭上眼睛 Which actually kind of seems like a lot to me… 这好像对我来说有点重要哦…… Okay. So, let’s get back to it.言归正传 You’re dead, your decomposition is starting.人死了 分解过程开始了 This is exciting.真刺激 Your cells are dead, and they are beginning to break down.细胞死亡并开始分解 In this case, cell death happens because of necrosis.此时 细胞出现死亡是因为坏死 It’s messy,场面很混乱 and without circulation没有了循环机能 the body can’t come clean up that dead cell matter.身体就无法清除坏死的细胞 As carbon dioxide builds up随着二氧化碳的累积 and the pH of the tissues in your body arise.身体组织的pH值升高 The cells weaken, and eventually their cell membranes break,细胞衰弱 最后细胞膜破裂 releasing the insides fluids into the surrounding tissue.细胞内的液体被释放到周围组织中 Enzymes in that fluid cause damage,细胞液中的酶会破坏组织 blistering and color changes,尸体出现起泡和变色 So this continues for a one while.这一过程会持续一段时间 By the second or third day, putrefaction sets in.到第二或第三天 尸体开始腐烂 Assuming you’re just leaving your body out.假设把尸体裸露在外 Oxygen has been depleted by the natural microorganisms呼吸道和消化系统中的天然微生物 in our respiratory and gastrointestinal systems.会将体内的氧气耗尽 And they’ve begun to spread into other sections of the body.并开始扩散到身体其他部位 For example: enzymes in the pancreas cause it to actually digest itself,比如 胰腺中的酶实际上是自己蚕食自己 and the gut bacteria love that!肠道细菌也虎视眈眈 so they eat it too,所以它也吃胰腺中的酶 which turns the abdomen into a greenish color.这会让腹部呈现成一种类似绿色的颜色 Gas begins to build up,气体开始聚积 forcing any non-digestibles like feces out of the body.迫使粪便等不能消化的物质排出体外 This is when the smell is just… it’s beyond horrible.这时的气味……简直无比可怕 Like it’s really bad.真的很臭 I’ve smelled it, you do not wanna smell it.我闻过 你不会想闻的 Two organic amine chemicals在这种相互作用中会产生 putrescine and cadaverine are created during this interaction,腐胺和尸胺两种有机胺化学物 and eventually this makes its way into the blood vessels.最终这两种物质会进入血管 Picture like a post-apocalyptic highway, right?就像驶入了末日高速路 对吧? Using that, they can get to the rest of the body and通过血管 它们能到达身体的其他部分 ooze out causing a really……释放出一股非常…… I can not stress this enough,难以言喻的 horrible rotting smell.可怕的腐烂味道 Eventually, necrosis and the work of bacteria 最终 在坏死和细菌的作用下 changes that greenishness of skin, to purple,皮肤由青变紫 and then to black.最后变成黑色 The smell causes more insects to come lay eggs这股味道吸引更多昆虫来这里产卵 and invade the body,并侵入人体 which has been happening already.这种情况一直在发生 But this is way more.但远不止这些 A single blowfly can lay 300 eggs which will hatch in a single day.一只绿头苍蝇能产下三百颗卵并在一天孵化 Their larvae will eat tissues nearby the egg site for a week卵孵化成蛆并在一周内 as a maggot before transforming into a blowfly and going away!吃掉卵周边的人体组织 然后变成苍蝇飞走 Over the next week,接下来的一周中 maggots and bacteria pop holes in the body,蛆虫和细菌让身体爆开洞 releasing the gas and the smell, even more.释放出气体和味道 甚至更多物质 These maggots can consume 60-percent of a body in like a week!这些蛆虫一周左右便可吃掉60%的尸体 But there’s still a lot to go,但腐烂过程远远不止如此 Because again this was just the first week, guys.因为这仅仅是第一周 Next, butyric fermentation starts接下来 丁酸开始发酵 and the organs and tissues begin to dry out and wax over.器官和组织开始变干和蜡化 Think of like a mummy in a museum!就和博物馆里的木乃伊一样 The tissues are being slowly digested 这些组织会慢慢地被 by more bacteria, insects, protozoa, and fungi.更多细菌 昆虫 原生动物和真菌消化 This stage takes a long time,这个阶段会持续很久 maybe as much as a year or more in moderate temperatures.在适宜温度下可能需要一年甚至更久 Faster in hot temperatures, slower in cold ones.温度高时比较快 温度低时比较慢 Once the fluids are mostly dry, post-decay starts.当体液基本变干 腐败后的过程开始了 The soft tissues and organs are pretty much dried up and consumed,软组织和器官将近萎缩 耗尽 but bones and hair, cartilage 但骨骼 毛发 软骨和 and sticky by-products of these earlier stages are all still around.前几个阶段的粘性副产物依然存在 This is when a variety of beetles and flies move in这时各样的甲虫和苍蝇来了 each species looking to eat away part of what’s left.每个物种都想吃掉剩下的部分 Over the subsequent years,在随后几年里 plants and animals will eat away the skeleton and eventually…植物和动物会吃掉遗骸 最后…… dust to dust.尘归尘土归土 You are gone forever.你永远消失了 Of course, in modern life,当然 在现代 we usually never get past the first few days.我们通常不会经历前几天 Embalming helps delay much of these processes,尸体防腐处理有助于延缓这些过程 as does cooling the body down!低温处理也可以 This is more like if you left a human laying around,就像一个活人躺在那儿 you know, like an old pizza.但看着像块干瘪的披萨 Sure, we die.当然 人死了 But all these things live on 但多亏我们恶心潮湿的尸体 thanks to our gross wet corpses!以此为生的生物才能存活 It’s inevitable, and kind of fascinating.这是不可避免的 还有些迷人 I could do like five more episodes, just on all of these stuffs and what happens later.关于死后发生的这些 我还能再拍五集 Let us know what you think about this down below.在下面发表你对死亡的想法吧 Not like… down below like buried.我说的下面不是地底下 Just down in the comments.只是在下方评论 And make sure you hit subscrib for more D NEWs.请订阅《D新闻》了解更多 Laci did a vedio.Laci制作了个视频 You can find it over here.在这里可以看到它 About how we even know when someone dies.内容关于我们如何判定死亡 And me and Wilson talked about if you can be scared to death.我和Wilson还谈论过 人能否被吓得半死 Right here!就在这儿 Thanks for watching, everybody. Happy Halloween!感谢大家的观看 万圣节快乐
  • 2022-06-27电力过剩的小岛Yes, I am standing somewhere windswept and talking about infrastructure.是的 站在大风肆虐的地方 谈论基础建设 I have a style!是我的作风 Also, that whooshing sound you can hear?听到呼呼的声音了吗? That’s the other turbine that you can’t see in this camera shot.那是另外一个风力机 没办法在镜头中看见 Anyway, power grids! They have to balance supply and demand.无论如何 电网 必需平衡供给和需求 I’ve talked about that a few times in the past here. But as a quick catch up,过去我已经讲过几次了 不过还是快速解释一下 if there’s not enough power being generated, things break,如果发电不足 就会发生故障 but if there’s too much power being generated, things also break,但如果发电过多 也会产生故障 and arguably in a worse way.可以说是很糟糕的故障 There isn’t a battery in the world世界上没有哪种电池 big enough to deal with the daily peaks and troughs of national demand.电容量大到足以应对一国日常的高峰与低峰需求 So power grid engineers have to make sure that the power being generated因此电网工程师须保证产电量 is always close to the power that’s being used.总是接近用电量 There are a lot of possible technologies to help with that balance.很多潜在的技术手段 能助力于两者的平衡 And I’ve talked about some of those before here, too,在此之前我也讲过一些 pumped storage that uses a lake as a giant battery,比如抽水蓄能 使湖泊成为巨型电池 or even the big lithium-ion setup in Australia that’s only caught on fire once so far.或者是目前为止 着过一次火的澳大利亚大型锂电池装置 But all of those technologies assume that supply and demand但这些技术都假设 will balance each other out over time, usually over a few hours.供给和需求量通常在几小时内能达到平衡 What happens if you always have too much power?那么经常产电过量 会发生什么呢? Welcome to the Orkney Islands, in the far north east of Scotland.欢迎来到苏格兰遥远的东北部 奥克尼群岛 About 22,000 people live here, on around 1,000 windswept square kilometers.在一千平方公里被风肆掠的土地上 生活着两万多人口 And they have so much renewable energy from wind and waves and tides他们这里有太多风 海浪与潮汐的可再生能源 that it’s genuinely a problem.以至于这带来了问题 Solution number one is: turn off the turbines.方案一:关掉风力机 2013, we were producing up to 130% of our electrical needs.2013年 生产电量超过需求量的30% So there can be quite a lot of curtailment on several turbines.因此 风力机被大幅关停 There’s active network management.这里有自动电网管理系统 The wind turbine will be shut down because the network can’t handle the load.当系统负载过大时 风力机会被关闭 There’s been a moratorium on any new grid connections.暂停向电网输电 There is potential for some microgeneration, but nothing of any scale.风力机还会产生微弱的发电 但不会形成规模 So when you’re in a place like Orkney,在奥克尼这样的地方 where you have some of the best generation potential,虽然有很好的发电潜能 it’s a complete waste.但完全浪费了 Turning off the turbines isn’t a good solution. It’s wasteful.关掉风力机不是一个好的选择 这很浪费资源 Depending on the time of day and year,一天或一年内的不同时间 these islands need between 7 and 46 megawatts.奥克尼需要7到46兆瓦的电量 It’s almost always windy here, so a couple of big commercial wind farms这里几乎一直刮风 所以像这样的几个大型商业风力发电场 like this can produce all the power that folks here need.就能满足这里居民的用电需求 But they’ve also got 500 domestic turbines, privately owned.但是这里也有500台私人家用风力机 1 in 12 households generate their own power.每12户家庭中就有1户自己发电 Because why wouldn’t you?为什么不呢? Once you pay the installation costs,只要你支付了安装费用 you’ll probably turn a profit, year after year after year.你就能年复一年地获利 One of the things I struggled with, writing this script is我写这个脚本遇到的困难之一 that there is so much going on up here.就是这里正在发生许多事 There’s an electric hybrid plane being tested at the airport.机场正在测试一架电动混合动力飞机 There are tidal power experiments, wave power experiments.还有有潮汐动力实验 波浪动力实验 Every type of renewable energy, almost, is being tested here.几乎每一种可再生能源都在这里进行测试 There’s not much solar.除了没有多少太阳能 And there’s a backup:还一种备用能源: for the very rare days when the wind is calm,在少有的风平浪静的日子里 there are interconnector cables that can pull up to 40 megawatts from the Scottish mainland.互连电缆能从苏格兰本土输送高达40兆瓦的电力 But OK: they’re generating a massive surplus of power,但还好 它们与英国国家电网相连 and they’re connected to the British National Grid.能产生大量盈余电力 So surely solution number two is: use those interconnectors.所以第二个解决方案当然是:利用那些连接电缆 They can just sell the extra power back to the mainland.将多余的电力卖回本土 Well, those 40 megawatts that the interconnectors can handle?那么 互联电缆能应对40兆瓦的电量吗? That’s not actually all that much.其实电量并没有那么多 The interconnector cables we’ve got are small.这里的互联电缆电量很小 We reckon there’s 2,000 megawatts of tidal and wave generation around here.我们估计这里能产生2000兆瓦的潮汐能和波浪能 We reckon there’s 17,000 megawatts of offshore wind在几百公里范围内内 within a couple of hundred kilometers of here.能产生17000兆瓦的海上风能 The interconnector was built for an old day建设电缆是因为从前 when you used to burn coal and send us electricity.需要烧煤来为我们输送电力 That’s gone. We don’t do that anymore.这样的情况已经没了 我们不再这样做了 We now need to be in a position where we’ve got a better way现在我们需要找到一个更好的办法 to get the power from these islands away.来从岛上获取电力 If the new interconnector is built, it carry enough power对于奥克尼未来几年内可能建造的风力机来说 for all the turbines that Orkney could reasonably put up in the next few years.如果新的互联电缆建成 产生的电力就能够输送出去 They could power most of the highlands of Scotland.供苏格兰大部分高地使用 But building that new interconnector will cost a quarter of a billion pounds.但是建造新的互联电缆将花费2.5亿英镑 National government requires that the islands approve plans for enough国家政府要求奥克尼在获得批准之前 new turbines to make sure it’s going to be used, before it’s approved.确保有足够的风力机 让这些电缆能发挥作用 That’s all still in the balance politically.这在政治上仍然悬而未决 So solution number three is that the islands could start using more electricity.方案三:奥克尼可以尽力消耗更多电力 There’s already a larger share of electric cars here than anywhere else in Scotland.这里的电动汽车已经多于苏格兰的任何地方 But most vehicles still use petrol or diesel.但是大多数车辆仍然使用汽油或柴油 That could change. There’s still a lot of oil heating.可以改变这个情况 这里还大量用油供暖 The ferries, vital for getting around, still burn fossil fuels.重要的出行工具 渡轮 仍然依靠化石燃料 The transition is a slow process.转变是一个缓慢的过程 No one’s going to scrap a perfectly good car or heater or ferry unless they have to.除非万不得已 否则没人愿意报废一辆完好的汽车 取暖器或渡船 But there are plans.但是我们有规划 And Orkney’s also had a hydrogen fuel system for years,多年来 奥克尼一直有一个氢燃料系统 to help soak up a bit of the excess power.用来吸收多余的能量 We’re producing hydrogen from, effectively, spare electricity.实际上 我们正在利用多余的电力生产氢气 That’s why we started.为此我们开始行动 We’re taking electricity, putting it into fresh water,我们给淡水通电 and it splits the water into hydrogen and oxygen.将水分解成氢和氧 We’re getting rid of the oxygen and we’re just capturing the hydrogen.排除氧气 捕获氢气 We’re compressing it, and then we’re using it in this fuel cell.再压缩氢气 把它做成燃料电池 We have ferries that operate within the islands. One of those ferries岛内有渡轮运营 其中一艘渡轮 is able to be powered by this fuel cell when it ties up alongside at night.夜间停靠时能用这种燃料电池补充动力 And it saves it running its own engines,这样就不用发动引擎 or it saves it drawing power from the grid.也不用从电网获取电力 This is just the start of something.这只是个开始 This equipment is experimental这个设备是实验性的 and believe me, it’s not efficient.老实说 效率也不高 This is not the best way of doing it.这不是最好的方法 But we’re finding our way into new territory.但我们正在探索新的领域 We try and unearth some of the challenges so that when we scale this equipment up,我们试着挖掘一些不足 这样当我们扩大设备规模时 then those faults have been polished out.这些缺陷已经被消除 These islands are years ahead of the rest of the world.奥克尼领先世界其他地方好几年 This is the test bed.这里是试验台 This is a small version of the changes that the whole planet is going to make.是整个地球发展方向的小小缩影 The transition to renewables is happening faster here in Orkney than, I think,我认为 奥克尼向可再生能源的转变 anywhere else in the world.快于世界上任何其他地方 But as you travel around these islands, it just seems normal.但当你在这里旅行时 一切似乎都很平常 Nothing’s visibly changed, but the lessons没有什么明显的变化 that they’re learning here will hopefully pave the way for the rest of the world.但在这里学到的经验将有望为世界提供借鉴
  • 2022-06-27为什么东京设计得这么好This is a blueprint of Shinjuku Station,这是世界上最繁忙的公共交通枢纽 the busiest public transportation hub in the world.日本新宿站的规划设计图 This structure stretches one kilometer这一交通枢纽绵延一千米 through the Shinjuku district横穿新宿区 and facilitates 3.6 million daily commuters.每天能为360万通勤人员提供便利 We utilize it to go to different parts of Tokyo.通过它 人们可到达东京的各个地区 On its five main levels, you’ll find one of three major means of travelling.其五大主线占了人们主要出行方式的三分之一 For those on the go,对于那些忙碌的人来说 Shinjuku boasts three subway lines that are connected to sister districts新宿有三条地铁线路连接姊妹区 like Shibuya, Minato and Chiyoda,它们是涩谷 港区和千代田 all within minutes.都是几分钟的路程 Those using trains have their pick of five different railway companies新宿站有五家不同公司的子车站供乘客选择 that arrive and depart simultaneously,其地铁同时到达或者离开各地 located throughout the station’s 20 different platforms.并且子车站设置了20个不同的站台 If you’re looking to travel long distances, though,然而 如果你想长途旅行 Shinjuku’s impressive bus terminal hosts 1,600 long distance travel lines宏伟的新宿公交总站有1600条长途线路 that connect commuters, Tokyo and greater Japan.让通勤者与东京及整个日本连接起来 It’s a shining beacon of Tokyo’s envious and ambitious infrastructure design它是东京基础设施里宏伟又令人羡慕的一座发光的灯塔 and what’s crazier is the fact that this same formula is repeated更疯狂的是 同样的模式 throughout the mega city in different districts在这座特大城市的不同地区重复出现 all interconnected in an urban design而所有地区都因无与伦比的城市设计相互关联 that’s unmatched and quite frankly a masterpiece.坦率地说 这真是一件杰作 Tokyo is not just a city,东京不仅是一座城市 it’s a nation within a city.也是一个城中之国 The population measures 37 million people东京拥有3700万人口 meaning it’s the biggest megacity in the world.意味着它是世界上最大的特大城市 And when you consider the tourists and visitors from other parts of Japan,再想想还有来自日本其他地方的游客和访客 the numbers are even higher.人口会更多 Tokyo has 50% more people than any other urban setting globally.东京的人口比全球其他任何城市都多50% But despite the high population and never-ending movement,尽管城市人口众多 还有不断迁入的人员 it has often been known as one of the safest cities in terms of infrastructure.但就基础设施而言 东京经常被称为最安全的城市之一 City planners have not only found a way城市规划者不仅找到了一个方法 to make sure that the 3.9 billion yearly users来确保依赖于地铁网的39亿年度用户 who depends on the subway system get to where they need to go,能到达任何他们想要去的地方 but that they and others have alternative means of traveling并且能确保他们以及其他人在任一天 through Tokyo on any given day.都有可选择的出行方式穿越东京 If you’re walking, for example,举个例子 如果你正在走路 each Tokyo district has what you need right around the corner,你需要的东西在东京任何地方都可以找到 if not for a grocery store,如果不去杂货店购物的话 there’s tons of vending machines waiting for you.还有许多自动售货机可供你使用 Even though some bikes which make up 14% of full transportation in the city自行车占整个城市运输系统的14% have found a way to deal with the admittedly imperfect biking infrastructure,尽管找到方法解决了公认不完善的自行车基础设施 but while walking is convenient,但步行很方便 and an entirely viable option.而且是完全可行的选择 57% of travel in Tokyo is done through public transit,东京57%的出行依赖公共交通完成 which can be compared to New York city’s 58%,这可以和纽约58%的公共交通出行率相比 but that’s where the comparisons end.但只有在使用公共交通出行率上是相当的 Take a look at this 3D rendering of the Times Square 42nd street subway station,请看时代广场42街地铁站的三D渲染图 it’s no Shinjuku but it’s part of a public transport system这不是新宿 而是纽约公共交通系统的一部分 that is quite shockingly bigger than Tokyo’s.比东京的公共交通系统大很多 Seriously, the New York City Subway has 34 lines说真的 纽约城市地铁有34条线路 and 468 stations all servicing four boroughs,468个车站 全都服务于4个行政区 namely Manhattan, Brooklyn, Queens and the Bronx.即曼哈顿 布鲁克林 皇后区和布朗克斯区 But bigger doesn’t always mean better,但更大并不总是意味着更好 and that’s definitely the case here,这里的交通情况就是这样 because despite its size, it comes second to Tokyo’s annual passenger frequency.因为即便它的规模很大 年客流量却次于东京 This is possible because Tokyo system while much smaller is way more efficient.这可能是因为东京的系统虽然小得多 但却更高效 It’s the results of a necessity that grew over time随着人们不断地涌向大城市 空间越来越小 as people flocked to the big city and space decreased.这是一种必然的结果 The flexibility and constant work on each transport system每套交通系统持续灵活地运行 and the insane $200 billion annual budget加上 从2013年到2023年 for Japanese public construction from 2013 to 2023,日本在公共设施上疯狂投入2000亿美元的年度预算 which is 40% of their entire GDP, by the way,占其总GDP的40% make Tokyo a brilliantly built city.成就了一个光彩夺目的东京 But it didn’t get there overnight.但这样的东京并非一夜达成的 After the end of World War II,第二次世界大战结束后 Japan, like many other countries, had to rebuild its nation.日本跟其他许多国家一样 不得不重建家园 However Japan didn’t have access to oil reserves然而 日本无法获得石油储备 and expensive oil transport systems并且缺少昂贵的石油运输系统 which led to the auto boom in countries like the United States.不能像美国等国家一样推动汽车热潮 So the Japanese government in collaboration with private companies于是日本政府与私营公司合作 invested in railway lines投资铁路线 instead in an attempt to connect Tokyo’s more suburban areas with the city center.试图将更多的东京郊区与市中心连接起来 Combine this with the historically lower income of Japanese households再加上 日本家庭历来收入较低 and the demand for solid public transit grew,以及民众对稳定公共交通的需求不断增长 this completely left the car as a means of transport in the dust.因此 汽车运输完全望尘莫及 Hence it’s no wonder the average car ownership per household in Tokyo is 0.56,所以 难怪东京每户家庭平均汽车拥有量为0.56辆 which is shockingly low for a developed urban area这对于发达城市地区而言低得惊人 in comparison to a city like Chicago相比芝加哥这座城市 that has a car ownership rate of 1.12 per household.每户家庭的汽车保有率为1.12辆 Betting on public transport was a risky move将赌注押在公共交通上是一个冒险的举措 that paid all for Tokyo但却为东京带来了回报 as it’s one of the few examples of a system that is practical and profitable.因为它是为数不多的实用且盈利的系统之一 I know you’re probably thinking the same thing as me,我猜你可能和我想的一样 public transport and profit are words that don’t ever appear in the same sentence,认为公共交通和盈利从来不可能同时存在 but in the case of Tokyo, they do.但东京做到了 And to achieve this, Tokyo city planers为了实现这一目标 东京的城市规划者 collaborated with private builders与私营建筑商达成合作 and the government made the idea of using cars and taxis to get around the city政府尽可能让使用小轿车和出租车在城市中穿梭的想法 as unattractive as they possibly could get away with.变得尽可能不吸引人 Just look at Tokyo’s traffic,看看东京的交通状况 it’s a nightmare that can pretty much only be compared几乎只能与在洛杉矶臭名昭著的拥挤道路上 to long hours spent navigating LA’s infamous road congestion,花费大量时间导航相比 简直是噩梦一场 although Tokyo is worse for a very simple reason.尽管东京情况更糟糕的原因很简单 Take a look at the shuto expressway of greater Tokyo,看看大东京的首都高速公路 the winding and overlapping roads may make the US’s interstate highways,蜿蜒重叠的道路如同美国的州际公路 but with an extra feature但东京有个额外的特征 – a feature that US highways rarely have –美国公路很少有的特征 cartels.那便是垄断利益集团 Drivers along any expressway will run into a few of these,任何高速公路上的司机都会遭遇这种情况 and these guys take 25 yen per kilometer,这些家伙每公里要收取25日元 and after that the 150 yen in initial fees,还有150日元的初始费用 oh and there’s a 10% consumption tax,哦 还有10%的消费税 so, yeah, even if you’re going only five kilometers,所以 即使你只走了五公里 you end up paying 300 yen or 2.6 dollars.你最终要支付300日元或2.6美元 And if you do that every day of every week of every year, it adds up.如果你天天如此 总费用将会累积更多 If you travel greater distances though,然而 如果要行驶更长的距离 it requires expressway passes则需要高速公路通行证 that could cost you as much as 14,000 yen or $120需要花费14000日元或120美元 for specific areas over a one to two week period.持有此证 可在一到两周时间内来往特定的区域 It might sound ridiculous but it helps public support for transit systems.这听起来可能很荒谬 但却有助于公众支持交通系统 It makes it so there’s no competition这使得汽车运输在地铁 巴士和火车面前 when comparing cars with the subway, bus or train,没有一点竞争力 and that’s a good thing, because public transit in Tokyo这是一件好事 因为客观来看 is objectively the superior option to a capital city.公共交通是作为首都城市的东京的最优选择 Even if one did want to make a swing at using a car to get around,即使有人确实想乘车到处转转 they better have a lot of free time,他们最好有很多空闲时间 because a train or subway will get you to your destination much faster than a car will,因为火车或地铁相比汽车 能更快地把你送到目的地 as transit vehicles run on a strict time crunch因为公共交通工具的运行时间受限 operating within a minute of expected arrival or departure time.其操作需要在预计到达或离开时间的一分钟内完成 They’re also super fast它们的速度超级快 moving at 1.5 times the speed of a car是汽车的1.5倍 that’s submitted by speed restrictions, traffic and unpredictable roadblocks.因为汽车受限于路况和不可预测的路障 So yeah, public transit is the way to go所以 公共交通是可行性 and passengers only need one card to travel across Tokyo.乘客只需要一张卡即可走遍东京 The pasmo card, which might sound like it should go without saying,pasmo卡听起来像是个理所当然的存在 but before the 2000s, people would have to line up in huge crowds但在21世纪以前 人们不得不排大长队 to buy tickets from different train and subway companies.购买由不同公司发售的车票 And the pasmo card collaboration has solved this issue而pasmo一卡通解决了这个问题 while also leading to a shared railway system同时也形成了一个共享的铁路网 that has only unified Tokyo’s great infrastructure further.这只会进一步统一东京的伟大基础设施 Now you might be thinking that Tokyo subway and rail systems现在你可能会认为东京地铁和铁路系统的先进技术 are simply too technologically advanced to be compared to cities like New York.是纽约等城市无法轻易比拟的 But what Japan is doing is pretty basic,但日本正在做的事情是相当基础的 it’s not alien technology,这不是外星科技 it’s just common sense.这只是常识 I mean, look at this train from a terminal in Minato, Tokyo,看看这辆从东京港区站点驶来的列车 coupled with this one in Chicago,再一起看看芝加哥的地铁 or what about this subway in Shinjuku paired against this one in New York,或者把新宿的地铁与纽约的地铁相比较 they look alike,它们看起来很相似 the difference lies in what they are connected to,区别在于它们所连接的地点 as well as the maintenance that these systems are taken through daily.以及这些系统每天的维护情况 See, most of tokyo stations are empty through the night,看 东京的大部分车站在夜间都是空的 even the one in Shinjuku,就连新宿站也是如此 which makes it the perfect time to do the mandatory nightly inspection.这使得夜间成了进行强制性检查的最佳时机 Yep, you have been right.是的 你是对的 The subway tunnels and tracks are checked every night,地铁隧道和轨道每晚都要检查 minor damages are fixed,轻微的损害会进行修复 while major ones are reported and alternative routes are chosen.而严重的损害将上报并选择替代线路 But Tokyo goes even further than this但东京做的更多 by doing a thorough dismantling and inspection of all their train cars every four years.他们会每四年对所有火车车厢进行彻底的拆卸和检查 The cars are stripped down by hand这些车厢都是通过人手去拆卸的 and all parts are tested for malfunction before they’re cleaned and put back together.所有部件在清洁并重新组装之前都会经过故障测试 It’s a highly coordinated effort这是一项高度协调的工作 that ensures accidents along these stations, tunnels and railways are kept to a minimum,确保把这些车站 隧道和铁路沿线发生事故的概率减到最小 and unforeseen damages that caused all times are therefore virtually non-existent.因此几乎没有造成过不可预见的损害 Oh, and let me just quickly mention the Shinkansen,简单介绍一下新干线 Tokyo’s bullet train, that has a maximum operating speed of 320 kilometers per hour,东京的子弹头列车 最高运行速度为每小时320公里 making trips out of Tokyo a breeze.它让从东京出发的旅行变得轻而易举 A commuter could board 18 Kansen in Tokyo通勤者可以在东京登上18干线 and arrive at the Shin-Aomori Station in northern Japan只需3小时20分钟 in just 3 hours and 20 minutes.即可抵达日本北部的新青森站 The same can’t be said for Amtrak’s Acela train,美国铁路公司的阿西乐特快列车却并非如此 which is currently the fastest train in the United States,这是美国目前“最快”的火车了 and it does the same distance of 713 kilometers从波士顿到华盛顿 同样要行驶713公里 from Boston to Washington in seven hours.却要用时7个小时 So all in all, Tokyo is really well designed and connected in an efficient way.总而言之 东京设计很合理 交通运输效率高 And while it can look chaotic sometimes from an outside perspective,虽然有时从外部角度可能看起来有些混乱 like when you watch videos of the crosswalks,如你看的这些人行横道的视频所示 it’s really the exact opposite.而事实恰恰相反 Everything is well thought out,一切都经过深思熟虑 down to the smallest of details,直到最细微的细节 and everything seems so coordinated.一切似乎都如此协调 But that’s it for this video.这个视频就到这里 Thank you for watching. I’ll see you in the next one.感谢收看 下个视频见
  • 2022-06-27尼采的思想4:上帝之死The ideas of Nietzsche尼采的思想 Nietzsche and Nihilism尼采和虚无主义 Lecture 4 – Twilight of the Idols第四讲 偶像的黄昏 In his book ‘Twilight of the Idols’, Nietzsche announces,在《偶像的黄昏》一书中 尼采说道 ‘What is called idol on the title page“本书扉页上所说的偶像 is simply what has been called truth so far.就是迄今为止称作真理的东西 Twilight of the idols – that is:偶像的黄昏就是 the old truth is approaching its end.’旧的真理就要结束了” In the last lecture,在上一讲中 we investigated True World Theories我们研究了真实世界理论 which were examples of some of the ‘Old Truths’列举了一些尼采给出的 Nietzsche thought were on the decline.“旧真理”正在衰落的例子 In this lecture, we will investigate本视频我们将探讨 why Nietzsche thought these ‘old truths’ were appoaching their end.尼采为什么认为“旧真理”已行将就木 To do this, we will analyse what is perhaps为此我们将分析 Nietzsche’s most famous and controversial statement ‘God is Dead’.尼采最著名也最受争议的论断“上帝已死” We will look at what such a statement meant to Nietzsche,我们来看看该论断对尼采的意义 what led him to make such a bold pronouncement,是什么致使他做出如此大胆的声明 and what he thought would happen,以及如果该信念如他预期那样广泛传播 if this belief were to become as wildespread as he anticipated.会导致什么样的社会现象 So what did Nietzsche mean by his statement ‘God is Dead’?尼采的“上帝已死”是什么意思? On the surface it may appear that表面来看 he was referring to the observation that他指的是自己观察到 believe in the monotheistic god of Christianity was on the decline.对基督教一神论的信仰正在衰落 However, such a view is not generally accepted by modern-day scholars.然而 这种观点并不被现代学者普遍接受 Rather many suggest instead that with this statement,相反 很多人认为 Nietzsche wanted to symbolize his conviction that尼采想用这句话来象征他的论断 faith in true world theories in general was deteriorating.即人们大体上正渐渐放弃信仰真实世界理论 Many scholars and philosophers, who have been influenced by Nietzsche,许多受尼采影响的学者和哲学家认为 have claimed that in communicating the death of God to the masses.在向众人传达上帝之死讯息时 Nietzsche should be characterized as a modern-day prophet.应该把尼采称为现代先知 What is it about his message that那么尼采的什么思想 qualifies him for such an honorable title?使他有资格获得如此光荣的头衔呢? Nietzsche was only one of a number of thinkers in his time尼采是他所在时代众多思想家中 to recognize the growth in skepticism towards Christianity,唯一认识到人们对基督教 as well as other less prominent true world theories.以及其它籍籍无名的真实世界理论的怀疑正与日俱增的人 So surely this alone does not qualify him for the title of phophet.但这肯定不足以使尼采成为先知 Rather the uniqueness of Nietzsche’s messages相反 尼采预言的独特性在于 lay in his remarkable ability to foresee the potentially devastating consequences,他具有非凡能力 能预见潜在的毁灭性后果 which would befall those individuals而这些后果将降临到 unable to retain their faith in true world theories,那些无法坚定信仰真实世界理论的人身上 Nietzsche thought that when true world theories lost their influence,尼采认为 当真实世界理论失去影响力时 individuals would be torn from the very worldview,个人将从赋予他们生命意义的世界观 which gave their lives meaning and the strength to persevere in life赋予他们力量在艰难困苦时坚持生活的世界观中 despite sometimes miserable conditions.剥离出来 In short, Nietzsche understood that the death of God could简而言之 尼采知道上帝之死可能会导致 potentially vault a large majority of the human race into a state of Nihilism.绝大部分人陷入虚无主义的状态 The great Walter Kaufman, in his classic work on Nietzsche,著名的沃尔特·考夫曼在其关于尼采的经典著作中 described exactly why Nietzsche is often heralded as a morden-day prophet.详细描述了尼采频繁被誉为现代先知的原因 ‘Sometimes prophecy seems to consist in man’s ability“有时候预言似乎存在于人能够 to experience his own wretched fate so deeply深刻体验自己的悲惨命运 that it becomes a symbol of something larger.由此预言成了更广泛意义上的象征 It is in this sense that在这种意义上 one can compare Nietzsche with the ancient prophets.我们才能将尼采和古代先知相提并论 He felt the agony, the suffering尼采强烈地感受到苦恼 折磨 and the misery of a godless world so intensely,和无神世界的悲惨 at a time when others were yet blind to its tremendous consequence,当其他人还没意识到无神论造成的严重后果时 that he was able to experience in advance, as it were,尼采在某种程度上已经能够提前感知到 the fate of a coming generation.’下一代的命运” The generation following Nietzsche in many ways尼采之后的一代人在很多方面 seemed to have experienced the fate he had predicted.似乎已经经历了他预知的命运 As the historian Ronald Stromberg in his book ‘Redemption by War’ explained,历史学家罗纳德•斯特龙伯格在《战争救赎》一书中写到 ‘The turn of the 20th century marked the time20世纪之交意味着到了这样一个时刻—— when intellectuals in Europe were gripped by a growing sense欧洲知识分子被与日俱增的一个概念束缚 that life is meaningless.即“生活没有意义” And it was this feeling which can help to explain the now forgotten fact这种虚无感能够帮我们解释一个被遗忘的事实 that the vast majority of European intellectual were,即在一战前夕 in fact, pro-war in the years leading up for World War I.’绝大多数欧洲知识分子都是好战分子” Stromberg wrote,斯特龙伯格写到 ‘How, in the end, are we to explain this so fateful explosion of warlike ideas and sentiments“1914年欧洲知识分子中好战倾向致命性爆发 among all manner of European intellectuals in 1914?我们最终该如何解释这种现象呢? Of the ingredients we have found to be pervasive, all are important:我们所发现的普遍存在的原因都很重要 hatred of the existing society;对现有社会的仇恨 the apocalyptic ‘sense of ending’;末日终结感 need for some kind of worthy cause to give meaning to one’s life;需要某种有价值的事业来赋予生命意义 sheer thirst for adventure against the background of a dreary materialism…’现实世界枯燥乏味 强烈渴望冒险……” Fortunately,幸运的是 the morden age is much different than the spirit of the early 20th century,当代精神与20世纪初大不相同 as today most individuals are not fervent war supporters.因为今人大多不是战争发烧友 Instead, morden individuals seem to search for a cause相反 现代人似乎在寻找一个正当理由 which will give meaning to their life in different ways.来以不同方式赋予生活意义 However, this search for many appears to be a lost cause,尽管我们西方人享受着高水平的生活 as despite the high standard of living we enjoy in the west.但对许多人来说这种寻找似乎仍是徒劳 The question ‘what is it all for?’“这一切是为了什么?”这个问题 still grips most of us in our moments of solitude.在我们大多数人独处时依然横亘在心头 As the psychologist Victor Frankl pointed out,正如心理学家维克多·弗兰克尔指出 ‘For too long we have been dreaming a dream“长久以来 我们都在做一个梦 from which we are now waking up:如今梦醒了: the dream that if we just improve the socioeconomic situation of people,那个梦就是 只要改善社会经济状况 everything will be okay, people will become happy.一切就会好的 人们就会快乐起来 The truth is that as the struggle for survival has subsided,而事实是 随着生存斗争的平息 the question has emerged: survival for what?问题浮现了:我们为什么而活? Ever more people today have the means to live,如今 越来越多的人有了谋生的手段 but no meaning to live for.’却丧失了活着的意义” It is quite remarkable了不起的是 Nietzsche was able to hypothesize this ‘Nihilistic Mood’,尼采能够假设这种“虚无主义情绪” which has survived to this day.并且这种说法一直延续至今 Nietzsche announces ‘The Death of God’ in a famous aphorism,尼采在《快乐的科学》一书中 in his book ‘The Gay Science’ called ‘the madman’.借疯子之口说出名言宣布“上帝之死” In this passage, he tells a tale of a madman,在这篇文章中 他讲述了一个疯子的故事 who runs out onto the street screeching,疯子尖叫着跑到街上 ‘I seek God! I seek God!’“上帝去哪了 上帝去哪了” Understandably those on the street give him a strange look如你所料 行人奇怪地看看他 and continue on with their evening.就继续干自己的事了 However, the madman does not cease.但疯子并没有就此而止 He yells,他大叫起来 ‘God is dead!“上帝死了 God remains dead! And we have killed him!上帝已经死了 我们已经杀死他了 How shall we comfort ourselves, the murderers of all murderers…作为最大的谋杀犯 我们将如何宽慰自己 There has never been a greater deed;没有比这更伟大的事迹了 and whoever is born after us –而我们的后人—— for the sake of this deed he will belong to a higher history than all history hitherto.’亦将因此感到无上荣光” Despite the madman’s attempt to enlighten his fellow citizens,尽管这个疯子试图以上帝之死的严重性 regarding the enormity of the death of God,启迪他的同胞 the individuals on the street paid little attention to him.但街上几乎无人注意到他 When he noticed the utter indifference of those around him,当他注意到周围人完全漠不关心时 he threw his lantern on the ground他沮丧地把灯笼扔到地上 so that it broke in pieces and was extinguished.灯笼破碎成片 火熄灭了 ‘I have come too early,’ he said then;随后疯子说了句“我来得太早了” ‘my time is not yet.“时机未到 This tremendous event is still on its way, still wandering;上帝死了这件大事还没传播到此地 it has not yet reached the ears of men.’还没传到人们耳中” Later in his life,尼采晚年认为 Nietzsche reached the opinion that the loss of faith in true world theories对真实世界理论失去信心 was in fact the most glorious event to befall mankind.实际上是人类所遭遇的最光荣的事件 In his book ‘The Gay Science’, he wrote,尼采在《快乐的科学》一书中写到—— ‘In fact, we philosophers and ‘free spirits’ feel,事实上 对于我们哲学家和“自由的灵魂”来说 as if we are illumined by a new dawn,一听到“旧神已死”的消息 on receiving the news that ‘the old God is dead’;就觉得自己好像被新的曙光照亮了 our hearts overflow with gratitude, wonder,我们心中充满了感激 惊讶 premonition, anticipation.好的预感 以及期待 At last the horizon seems to us open again…终于 我们似乎再次看到了地平线…… the sea, our sea again lies open before us;大海 我们的大海 再度展现在我们眼前 perhaps there has never yet been such an ‘open sea’.’也许是前所未有的“开放之海” A universe, without God or without a transcendent purpose尼采认为 一个没有上帝的宇宙 driving the lives of men toward a common end,一个没有超然目的推动人们走向共同目标的宇宙 was in fact, a universe, according to Nietzche,实际上是一个强大的宇宙 we’re strong and creative individuals,在这个宇宙中 我们都是坚强而有创造力的人 could freely sculpt their own worldviews.可以自由塑造自己的世界观 However, this attitude of Nietzsche’s did not come naturally,然而尼采的这种态度并不是自然而然产生的 but was an attitude that he came to adopt only after years of而是他经历了多年的挣扎 痛苦和折磨后 struggle, pain and suffering.才逐渐形成的 Early in his life,尼采在早年间 Nietzsche experienced firsthand the misery of曾认为自己生活在无神世界 living in what he believes to be a godless world.他亲身体验了这种生活的痛苦 It was a world with no transcendent purpose这是一个没有超然目的的世界 and thus no meaning,因此也没有意义 in which mankind had no special place in the scheme of things.在这个世界上人类的行为没有特别的意义 In other words,换句话说 this world view led him to experience the agony of Nihilism.这种世界观让他经历了虚无主义的痛苦 In one of his earlier works ‘Human All Too Human’,在其早期作品《悲剧的诞生》中 Nietzsche expressed this agony, he wrote,尼采表达了这种痛苦 他写道 ‘But the tragic thing is that“但悲剧就是 we can no longer believe those dogmas of religion and metaphysics,人们一旦心中对真理有了严格的标准 once we have the rigorous method of truth in our hearts and heads,就不会再相信那些宗教和形而上学的教条 and yet on the other hand,而另一方面 the development of mankind has made us so delicate, sensitive, and ailing人性的发展也使人类变得太脆弱 敏感和病态 that we need the most potent kind of cures and comforts —人们迫切需要最有效的疗愈和安慰 hence arises the danger that man might bleed to death from the truth he has recognized.而结果是 知道真理的人可能会流血而亡 Byron expressed this in his immortal lines:拜伦用他不朽的诗句表达了这一点 Sorrow is knowledge:忧患为知 they who know the most通晓天下之最者 must mourn the deepest over the fatal truth,必极深痛于致人死命之真理 the tree of knowledge is not that of life’.知识之树 非生命之树矣 The question we will now examine is:我们接下来要探讨的问题是 Why he held the conviction that ‘God was dead’?为什么尼采坚信“上帝已死”? In our modern times, it is usually taking for granted that,现在的我们一般会理所当然地认为 the general decline of faith and religions and true world theories,宗教信仰和真实世界理论的普遍衰落 is a result of growth of the natural sciences.是自然科学发展的结果 However, Nietzsche took a different stance.但是尼采持不同的立场 In his book ‘The Dawn’, he illuminated his position:他在《朝霞》一书中阐明了自己的立场 ‘In former times, one sought to prove that there is no God –“从前 人们试图证明上帝不存在 today one indicates how the belief that there is a God could arise现在人们却表明上帝存在这种信念是如何形成的 and how this belief acquired its weight and importance:以及其如何获得分量和意义 a counter-proof that there is no God thereby becomes superfluous.使上帝不存在的证明因此变得多余 When in former times one had refuted the ‘proofs of the existence of God’ put forward,以前 当人们驳斥了“上帝存在证明”之后 there always remained the doubt whether better proofs might not be adduced than those just refuted:人们依然总是怀疑 是否能提出比这些证明更好的证明 in those days,那时候 atheists did not know how to make a clean sweep.’无神论者还不知道如何追本溯源 Nietzsche didn’t think it was possible尼采认为不可能通过提出一个 to refute the existence of true worlds by putting forth an argument,利用科学所确定的最新发现的论点 which utilized the lastest finding as certained by science,来反驳真实世界的存在 as he understood因为尼采知道 that true world believers would counter with arguments of their own.真实世界的信徒也会捍卫自己的论点 Instead, Nietzsche thought相反 尼采认为 he had refuted the existence of true worlds他用卓越而敏锐心理学洞察力 with his keen and penetrating psychological insights.驳斥了真实世界的存在 He looked into the mind of the believer他深入信徒的内心 and understood why it is they held such beliefs.明白了他们为什么会持有这样的信念 Faith and true world theories, Nietzsche espoused,尼采认为 人们对真实世界理论的信仰 fulfilled deep-seated psychological needs-满足了他们根深蒂固的心理需求 such theories were created by individuals in need of solaces这些理论是由需要慰藉的个人创造的 to protect them from the harsh realities of this life.以保护他们免受生活严酷现实的伤害 Before we conclude,本视频结束之前 we will examine an apparent contradiction in Nietzsche’s thought我们来看看尼采的上帝之死观点中 with regards to his views on the death of God.一个明显的矛盾 In a very important and often neglected passage from his book尼采在《悲剧的诞生》一书中 ‘Human All Too Human’,有一段非常重要却经常被忽略的话 Nietzsche admits that for all we know尼采承认 就我们所知 a true world, or what he here calls it a metaphysical world,一个真实世界 即他所说的形而上学世界 could indeed exist.确实可能存在 He wrote:他写道 ‘It is true, there could be a metaphysical world;“的确可能存在一个形而上学的世界 the absolute possibility of it is hardly to be disputed.’它的绝对可能性是不容置疑的” Of all the misunderstandings Nietzsche has been the victim of in the last century,上个世纪尼采一个人扛下了所有误解 and there have been many.误解至今仍有 One of the most erroneous of them all would be to call him a dogmatist.最大的一个误解就是称尼采为教条主义者 Nietzsche, as the above quote signifies,尼采 正如以上引用所言 admitted that a true world or Gods for that matter他承认 一个真实世界或神明 could exist for all he knew.可能存在于他所知道的一切 As human beings, we are fallible animals.我们人都是容易犯错误的动物 And our knowledge of this vast universe is extremely limited.我们对浩瀚宇宙的了解是极其有限的 And so in terms of the existence of the true worlds,所以就真实世界是否存在而言 we really have no way of knowing one way or the other.我们真的没有办法下断言 This may appear at first glance to be a contradiction in Nietzsche’s thoughts.乍一看 这似乎是尼采思想中的一个矛盾 How could he proclaim the death of god他怎么能一边宣告上帝已死 while also state that a true world could exist for all we know?一边附议真实世界可能存在于我们所知的一切呢? This possible contradiction is cleared up with the realization that,这个可能的矛盾也得到澄清了 Nietzsche thought that his psychological insights into the mind of the believer因为尼采认为他对信徒心灵的心理洞察 had discredited the validity of true world theories.已经使真实世界理论的有效性受到质疑 But he did not think it had disproved the existence of the true world,但尼采并不认为这足以否定真实世界的存在 whatever that may be altogether.无论它可能是什么 In the back of his mind,在尼采的内心深处 Nietzsche was always aware that he, like all other humans,他一直觉得自己和普通人一样 did not have special access to ultimate truths,没有特别的机会接触终极真理 whatever such truths would entail.不管这些真理会带来什么 So although he claimed God is dead,即使尼采宣称上帝已死 he admitted that in fact, a true world,他也承认真实世界的存在 in some form or another, could indeed exist.可能以在某种形式确实存在 However, Nietzsche himself was steadfast in his conviction to live the rest of his life然而 尼采本人坚称 without believing in any form of a true world.自己余生不相信任何形式的真实世界存在 The reason for such a conviction being utilitarian, that is,真实世界存在这种信念之所以功利 he thought that his life,是因为尼采认为自己的生活 and in fact that the lives of all human beings,乃至全人类的生活 would be more successful without such a belief.如果没有这样的信念 会更加成功 By believing a better life is awaiting one following death or some point in the future,因为人如果相信死后或未来某刻会有更好的生活 the individuals escapes from the responsibility and burden of having to make the most of this life.他们就会逃避现实生活中的责任和负担 Thus, in discarding faith in true world theories,因此 抛弃对真实世界理论的信仰之时 an individual is left alone in this world,一个人将独自留在这个世界上 with the choice of either making the most of it,要么选择过有价值的生活 or spending their days in a state of guilt and self-pity over what could have been.要么在内疚和自怜中度日 Therefore, for more than any other reason, Nietzsche proclaimed ‘the Death of God’,因此 尼采宣布“上帝之死”的原因无他 because he felt 仅仅因为他认为 that the world composed of individuals who did not believe in true world theories,由不相信真正世界理论的个人组成的世界 would be a much better world.将会是一个更美好的世界 In his aotobiography ‘Ecce Homo’,尼采陷入疯狂不久前 written shortly before Nietzsche descended into madness,他写成了一本自传《瞧 这个人》 he conveyed this idea, he wrote:里面表达了这样一种观念 ‘The concept ‘beyond’, ‘true world’ invented构想出“超越”“真实世界”等概念 in order to devalue the only world there is—是为了贬低唯一存在的世界 in order to retain no goal, no reason, no task for our earthly reality!’让我们的生活没有目标 没有理由 没有使命” In the next lecture,下期视频 we are going to investigate the phenomenon of Nihilism from Nietzsche’s perspective,我们要从尼采的角度来研究虚无主义现象 looking at among other things:看看虚无主义的其他方面: the difference between active and passive Nihilism,积极虚无主义和消极虚无主义的区别 and why Nietzsche thought Nihilism was a ‘transitional stage’.以及尼采为什么认为虚无主义是“过渡阶段” We will then have put ourselves in a good position for the final lecture,一起拭目以待下期视频吧 where we will look at different ideas Nietzsche thought,我们将看到尼采的不同想法 would help an individual overcome in Nihilistic Mood.它有助于人克服虚无主义情绪哦
  • 2022-06-27海底秘境——盐池The deep sea is a peculiar wonderland of underwater worlds深海是水下世界的奇异仙境 that the ocean holds in secret.是海洋的秘境 At mid-ocean ridges,在大洋中脊 towering hydrothermal vents pump superheated mineral-rich fluids高耸着的深海热泉将温度极高且富含矿物质的液体 out into the water,喷入海水 supporting a collection of curious creatures.为一群奇特的生物提供养分 Meanwhile, swarming the sunken carcasses of whales还有 沉入水底的鲸鱼尸体上 are communities of scavengers converging to feed on the decaying carrion.挤满了以腐肉为食的食腐动物所集合而成的群落 But perhaps even stranger than these two unexpected ecosystems但相较于这两种不可思议的生态系统 are the brine pools,更为奇妙的 或许就是 vast cumulations of saline-saturated water.积聚着饱含盐分的海水的——盐池 The display is surreal deep water lakes这沉睡在海底深处的湖泊 resting on the ocean floor展现出犹如梦幻般的奇观 and seem to defy the laws of physics.就好似有悖物理定律一般 Though unexplained and alluring,尽管迷人又充满着未知 these are highly toxic death traps for many creatures.对于许多生物来说 它们却是有剧毒的死亡陷阱 On the one hand,一方面 在海底 the pools themselves create undersea death zone on the ocean floor.盐池本身制造出了水下的死亡区域 And yet, on the other,然而 另一方面 they provide the basis for life through chemosynthesis,它们又通过化能合成作用提供了生命的基础 supporting vibrant gardens of life.供养着生机盎然的生命花园 Two distinct worlds,两种截然不同的世界 existing side by side, at the bottom of the endless blue.在无尽的海洋底部并存着 [Music Playing][音乐播放中] Brine pools are a hauntingly beautiful landscape.盐池有着令人梦萦魂牵的美景 The Gulf of Mexico contains a large number of these lakes,在墨西哥湾 有大量的盐池湖 varying in size from 1 meter across它们大小不一 跨度从小到1米 to up to 20 kilometers long.至长达20千米不等 And their origins can be explained by the processes of salt tectonics.而它们的起源可以从盐岩构成的过程说起 During the Jurassic period,在侏罗纪时期 the gulf was a shallow sea这里是片浅海湾 that became closed off from the rest of the ocean那时它被周围陆地包围 by the surrounding land.与海洋的其他部分隔开来 Over time, the sea evaporated,时光荏苒 海水蒸发 leaving behind a layer of salts and minerals.留下了富含盐分和矿物质的表层 Layers of sediment buried the salt bed over time,随着时间推移 盐床埋藏在沉积物表层下 protecting the minerals from being dissolved后来 墨西哥湾再次融入大海 when the gulf later rejoined the world ocean.矿物质在盐岩层的保护下没有被海水溶解 Under the weight of sediment and water,在沉积层和海水的重压下 the salt bed deformed and shifted.盐床开始变形和移动 Cracks and the sediment above海水顺着上层沉积物和裂缝 allowed water to creep down to the ancient salt deposits,渗入古老的沉积盐内 dissolving the salt into a concentrated brine.将这些盐分溶解为盐卤水 Along with trapped gases,由于盐层的变形与开裂 the brine was forced out of the seafloor盐卤水顺着喷涌而出的气泡 by warping and cracking of the salt plates.被挤出海底 Highly salty water seeped up into the ocean,高盐分的水渗入海洋 where its density far exceeded that of the water that surrounded it.它的密度远远超过周围的海水 This difference in density密度的差异 allowed the brine to flow across the seafloor landscape使盐卤水得以流经海底地貌 where it pooled into basins,汇聚成盆地 forming expansive lakes.形成广阔的湖泊 At certain points along their length,盐卤水会顺着盐池周围的某些点 the brine overflows and trickles down like a waterfall.形成瀑布一般的细流向外溢出 This is the outflow正是这种溢出 which maintains the level of the pool不断地向下层盐床补充盐卤水 while it’s replenished continually from the salt beds below.才使得盐池的水平面得以维持 But the landscape here is characterized also然而 构成了这里独特景观的 by a series of strange ridges, slopes and valleys还有一连串奇异的山脊 山坡和山谷 caused by salt tectonics and mineral deposition它们是盐岩层构建和矿物堆积 sculpting the overlying landscape.塑造出来的覆盖层地貌 This encased the brine pools in mineral dams of their own creation,这一奇特地貌 使得盐池被其本身所形成的矿物堤坝包裹起来 and laid the foundations needed for the birth of a whole new ecosystem.也为全新生态系统的诞生 打下了基础 Brine pools create two distinct environments盐池创造出两种全然不同的生态环境 that exist side by side in equilibrium on the seafloor.它们相互平衡 同时并存于海底 [Music Playing][音乐播放中] Within, the brine itself is toxic to most organisms,盐池中的盐卤水本身对大多数生物是有毒的 for it contains almost no oxygen,因为它盐浓度太高 且几乎不含氧气 and is far too salty to support life.无法供养生命 In addition, the dense layer of brine harbors toxic chemicals此外 盐卤水的致密层蕴含着有毒的化学物质 such as hydrogen sulfide and methane.比如硫化氢 还有甲烷 When an organism enters a brine pool,如果生物进入盐池 they attempt to breathe the hypersaline environment,试图在高盐环境下呼吸的话 which in many cases brings on toxic shock.多数情况下会陷入中毒性休克 Those who delve below the surface never return,扎进盐池里的生物无一生还 and they become pickled,之后它们的尸体被腌泡起来 their bodies preserved in perpetuity within the brine将在盐卤水里永久保存 for centuries without decay,几百年不会腐烂 like these crabs, which may have lost their footing就如同这些在盐池边 while searching for prey along the shores.捕猎觅食失足滑落的螃蟹一样 The grey crust that seems to cover the insides of the pools这层似乎覆盖了池水和动物尸体的 and the bodies within,灰色的外壳 are crystals of barium sulfate是盐卤水析出的 that precipitates out of the brine.硫酸钡结晶 The deadly nature of these pools has earned them a number of titles,盐池致命的特性使得它臭名昭著 they are often dubbed “pits of despair” and “hot tubs of death”,常被称为 “绝望陷阱” 及 “死亡热水池” and it’s easy to see why.而这也不难理解 But despite this,尽管如此 around their perimeter,这些死亡陷阱的周边 these death traps create biological hot spots on the seafloor.却形成了海底的生物热点地区 There is a fine border between where life seems altogether absent在一条精妙的边界一侧 似乎完全没有生命迹象 and where it’s able to thrive in great abundance.而另一侧 却是生机勃勃 Tiny amphipods dwell atop a mineral-rich biologically diverse seafloor.微小端足生物栖息在富含矿物质 生态多样的海底 Vast colonies of tube worms stretch beyond the dim horizon,巨大的蠕虫群落一直延伸出海底昏暗的地平线 while the shores are fringed with dense mats of giant mussels.而盐池边缘生长着密集的巨型贻贝床 Life is found in such high abundance here这里能发现如此大量的生命 for a number of reasons.是有一些原因的 The ridges and valleys surrounding the pools环绕盐池的山脊和山谷 provide a hard substrate for sessile organisms,为管状蠕虫 海百合和海葵等固着生物 like tube worms, crinoids and anemones to attach to.提供了牢固的生长基底 In contrast, out on the soft muds相反 在构成大面积深海平原的 that comprise much of the abyssal plain,软泥之上 these organisms can not settle.这些固着生物则无法栖息 [Music Playing][音乐播放中] In addition, brine pools are regions of high primary productivity.另外 盐池是有较高初级生产力的区域 Food is scarce in the deep sea.海底深处食物匮乏 The lack of sunlight means there are no photosynthesizers缺少阳光意味着 没有能进行光合作用的生物 like plants or phytoplankton例如植物或者浮游生物 to generate energy and form the base of a food web.来产生能量 供给食物链的基础所需 So instead, many creatures of the deep作为替代 深海里的大量生物 are drawn to chemosynthetic oasis被深海热泉和盐池之类的 like hydrothermal vents and brine pools有化能合成作用的绿洲所吸引 where they rely on energy derived not from the sun,在那里 它们依靠的不是源于太阳的能量 but from chemicals.而是源自化学物质 At these pools,在这些盐池中 it’s the presence of the toxic dissolved gases正因可溶解有毒气体的存在 that support the unique food web.才支撑起独一无二的食物链 These chemicals, though deadly to the animals themselves,虽然这些化学物质 对动物本身是致命的 are converted into food by specialized bacteria却可以被特殊的细菌 through the process of chemosynthesis.通过化能合成作用转化成食物 This forms the foundation of the ecosystem这形成了海底生态系统的基础 as the bacteria here occupy the role of producers因为细菌在这里成为了能量生产者 held by phytoplankton, in the sunlit surface waters.起到了光照水域上浮游植物的作用 Thus, a community of uniquely specialized organisms就这样 一个独一无二的特化生物群落 thrives on the borders of a toxic dead zone.在有毒的死亡地带蓬勃兴旺起来 An entire ecological system has developed一整套生态系统得以发展壮大 within habitants interacting through symbiosis, predation,正是栖息其中的生物彼此共生 捕食 and fierce competition for space and nutrients.为了争夺地盘和养份激烈竞争 相互作用的功劳 The mussels depend on these chemosynthetic bacteria贻贝依靠着生存在自己鳃内的 living within their gills for survival.可以进行化能合成作用的细菌存活 And together, they form a mutualistic relationship.同时 它们形成了互相依存的关系 In return for supplying the energy needed to sustain themselves and the mussels,细菌供给能量维持贻贝和自身的生存需求 the bacteria are protected from being predated by grazers作为回报 贻贝则保护细菌 that stalk the shores of the lakes.免遭岸边非肉食动物的窥视捕食 In their large numbers,大量双壳贝类集聚起来 these bivalve aggregations create a rocky beach for the pools为盐湖构建了坚如岩石的湖畔 partaking in a commensal relationship它们和蜗牛 虾 大螯虾 with snails, shrimp, and squat lobsters建立了共生关系 that use the mussels for shelter,这些动物或是把贻贝作为掩体 or trail across their shells in search of the bacteria.或是在贻壳之间穿行 觅食细菌 Larger predators also make the most of these gardens of life,大一些的猎食者如章鱼 鳗鱼和大型蟹类 like octopuses, hagfish, and large crabs也充分利用了这些生命花园 visiting the pools opportunistically to feed on the mussel beds.它们伺机造访盐池 以这里的贻贝床为食 But often, these delicate ecosystems are at risk of collapse.但这些脆弱的生态系统常常面临崩溃的风险 In some cases,有些情况下 the fragile perimeter oozes of the lakes’ crumble,盐池脆弱的边缘 会在崩裂处发生渗出 whelming the mussel beds with toxic brine有毒的盐卤水淹没贻贝 that leaves behind a boneyard of shells.将这里变成布满贝壳的坟场 Brine pools represent a hidden world盐池展现了一个隐秘在海洋深处 of fascinating ecology in the depths of the ocean.有趣迷人的生态世界 They are islands of abundance,它们是富饶的小岛 isolated from one another by the barren abyssal plain,被贫瘠的深海平原隔绝开来 and home to crowded congregations of life也是生命种群荟集的家园 interacting and coexisting in a bizarre landscape.它们相互作用 在奇异地貌里共同生存 In many of the ecosystems found in the deep sea深海里发现的许多生态系统 from whale full communities从鲸落群落 to scalding hydrothermal vents and toxic brine pools,到滚烫的深海热泉 有毒的盐池周边 there is a pattern of life thriving in very close proximity to death.存在着极其接近死亡 却又蓬勃旺盛的生命的模式 Whether organisms are deriving nutrients from sunken corpses无论生物 是从数十年来带给贫瘠的深海平原 that give life to the barren abyssal plain for decades,基础生命供给的沉尸中汲取营养 or somehow finding a way to exist in the fine gradient还是在那些供给能量的死亡陷阱 与死气沉沉海底之间 between an energy-giving death trap, and the lifeless seafloor,微妙的变化梯度中设法生存 the richly diverse creatures of the deep are specialized to survive在一度被认为完全没有生命存在的领域里 in a realm once thought to be devoid of life altogether.丰富多样的深海生物被环境所特化 而得以存活 And since their discovery,自从它们被发现以来 brine pools have represented a new frontier盐池便成为了海洋深处 for research and exploration down in the ocean depths.研究与探索的全新领域
  • 2022-06-27万能溶剂—水Chemicals like turpentine, ethanol, and sulfuric acid松节油 乙醇 硫酸等化学物质 are great at dissolving stuff.具有很强的溶解能力 they can break down paint, oil,它们可以分解颜料 石油 metal, skin, bones, and more.金属 皮肤 骨骼等物体 But there’s another liquid out there但还有一种液体 that can dissolve more substances能够溶解掉 than perhaps anything else on the earth:地球上几乎所有其他物质 water,它就是水 which is sometimes called “the universal solvent”. 有时人们称它“万能溶剂” Yet this super-dissolver is everywhere;这种超级溶剂随处可见 it falls from the sky and fills our pipes,从天而降的是它 灌满水管的是它 it’s what we bathe in, wash our hands with,我们用水洗澡 洗手 and pour down our delicate throats. 甚至把水倒进我们脆弱的喉咙里 If water is such a powerful solvent,如果水有这么强的溶解力 why doesn’t it dissolve everything away?它为什么没有把一切都溶解掉? Welcome to MinuteEarth.欢迎收看分钟地球 It’s true that water is really good at dissolving lots of stuff.的确 很多物质都易溶于水 For a liquid to dissolve something,液体溶解物质 it has to pull apart the molecules that make up that substance,需要将构成物质的分子拆分开来 and keep them apart.并使其保持分离 Water is pretty much built for that job,水能很好地胜任这个工作 its molecules have strong positive and negative charges,它的分子有很强的正负电荷 so they can pull apart and get between other molecules,因此它们可以分离并进入其他分子 or pieces of molecules with charged parts.或带电分子的碎片之间 And lots of different molecules out there happen to have charged parts,并且有许多不同分子碰巧是带电分子 which means that lots of different substances on our planet dissolve这意味着我们地球上各种物质 at least to some extent in water.在水中至少都会有某种程度的溶解 That’s why water is our go-to for cleaning stuff.这就是为什么水是我们清洗东西的首选 It can dissolve sticky orange juice right off your counter水仅仅是将黏黏的橙汁从柜台上溶解掉 or blood off your clothes.或将血迹从衣服上溶解掉 But water doesn’t dissolve the counter,但是 却没有溶解掉柜台 or the clothes, or our windows, or streets.也没有溶解掉衣服 窗户以及街道 which at first glance seems like a pretty lucky coincidence.这乍一看像是个颇为幸运的巧合 I mean, it would be not great我的意思是 if cleaning something would make it disintegrate, 如果什么东西洗一洗就分解了 or if rain could wipe out an entire city.或者 雨水能摧毁整座城市的话 就太糟了 But the super dissolving abilities of water但是水超强的溶解能力 are exactly why our world is built the way it is,正是世界表现为现在的样子 or really, the way it isn’t.而不是其他样子的原因 We make our countertops with quartz,我们用石英制作厨房台面 our clothes with cotton, our windows with glass,用棉花做衣服 用玻璃造窗户 and our streets with asphalt用沥青铺马路 because water can’t dissolve these materials.是因为水不能分解这些材料 They’re made mostly of molecules with no charged parts.它们主要由不带电粒子组成 It would be silly to build, say, windows with something用糖之类在水中能溶解的材料 that can dissolve in water, like sugar…制造比如说窗户 是个很蠢的行为 unless you’re going to eat them.除非你想把窗户吃掉 And lots of the substances that water DOES dissolve,很多可溶于水的物质 like washable markers, 比如可水洗记号笔 are things we engineered so that they can be washd away.是我们特意设计的可水洗产品 We’ve also engineered versions that aren’t dissolvable in water不想让产品被洗掉的时候 for when we don’t want them to be washed away.我们就设计不溶于水的版本 By making sure water dissolves what we want it to通过保证水只溶解我们要溶解的东西 and only what we want it to.而不溶解其他东西 We’ve been able to adapt a life to a world人类的生活已经适应了 in which water dissolves so much stuff.水能溶解如此多物质的世界 We humans also literally adapted to a world我们人类自身真正适应了 in which water dissolves so much stuff.这个水能溶解如此多物质的世界 The outer layer of our skin is built in a way that makes it uncharged我们皮肤的表皮层是由不带电的分子构成 and therefore undissolvable.因此不会被水溶解 And the membrane surrounding each of the cells inside us我们体内每个细胞的细胞膜 has a similar undissolvable layer.都有类似的不可溶解的结构 The only reason we humans exist at all on this watery planet我们人类能够存在于这颗充满水的星球 or that trees, fish, bacteria, or anything else exists或是树木 鱼类 细菌等存在的唯一原因 is that we evolved barriers that could keep water是我们进化出了可以阻隔水的屏障 from dissolving us into goo.以防止我们被水溶解成粘液 Any life forms that didn’t were simply dead in the water.不具备这一点的生物就直接丧命于水中了 Realizing our entire planet is built around意识到整个地球都是围绕着 water’s awesome dissolving ability水的强溶解力建立的 has changed how I see the world改变了我看待世界的方式 which is one of our goals at MinuteEarth.这也是分钟地球的目标之一 It’s also why we’re partnering with MEL Science,以及我们与MEL Science合作的原因 a kids’ subscription kit that truly brings science to life.这是儿童会员礼包 它能真正使科学走进生活 MEL’s hands-on activitiesMEL的动手活动 transform the invisible science happening all around us将我们身边无形的科学 into something accessible,变得触手可及 like this awesome tin hedgehog,就像这个有趣的锡刺猬 which got my kids super excited让我的孩子对不同化合物 about the crystal structures of different compounds.的晶体结构产生了浓厚的兴趣 Plus, along with a monthly subscription,此外 一月一次的更新 you’ll get access to live classes with professional teachers,将使你有机会参与专业老师的授课现场 and an augmented reality app还有一个增强现实应用 to dive deeper into the scientific concepts.帮助你更深刻地理解科学概念 We’ve been talking with MEL我们与MEL讨论过 about some really exciting partnership ideas,一些令人激动的合作想法 but first we need to see if our viewers are as excited about但是首先 我们需要了解观众是否 what MEL does as we are.对MEL和我们同样感兴趣 So go check melscience.com.那就去MEL的网站看看吧 And use code MINUTE50 to get 50% off your first box.使用优惠码MINUTE50 即可享受首单五折 That’s melscience.com,网址是melscience.com promo code: MINUTE50优惠码:MINUTE50 Thanks, MEL.感谢MEL的支持
  • 2022-06-27内含玄机的刺客茶壶[upbeat music][欢快的音乐] This is an assassin’s teapot.这是把刺客茶壶 It can be used to pour yourself a drink可以用它给自己倒一杯茶 and to pour a drink for your enemy.再给敌人倒一杯 You can then down your drink然后喝掉自己的那杯 to prove that the drink isn’t poisoned.以此证明茶没有毒 There’s no poison there.你看 没有毒 Don’t worry about the poison, there is no poison.别担心 根本就没有毒 But then when your enemy takes a drink,但一旦敌人喝了下去 they find out that it is poisoned.他就会中毒 And by the way, this doesn’t require you to spend而且你无需花几年时间 the last few years building up an immunity to iocane powder.研制解药 It works straight off the bat, no preparation required.这把茶壶很容易上手 无需提前准备 That’s because the assassin’s teapot因为它 can be used to pour three different drinks,能倒出三种不同饮料 which I’ve shown here using three different colored liquids.我们在此用三种颜色的液体来区分 And by the way, if you plan to poison your enemy,插一嘴 若你想给敌人下毒 I recommend using liquids of the same color.那还是建议使用同种颜色的液体 Do I need to tell the viewers that they shouldn’t我是否该告诉观众给别人下毒 be trying to poison people, legally?是犯法的呢? Just ’cause it would break the flow of the video.但这会打断视频的连贯性 Film myself having a fake phone call with a lawyer哦 把我假装和律师打电话 in which I explain the problem,解释这个问题的过程拍下来 and so long as I say out loud, “Don’t try to poison people,”只要我大声说出:“别给别人下毒” then that should have me covered?就没事了 Okay. Click.好的 明白了 The way you choose the drink is by sneakily选择其中一种饮料的方法 covering up one of these holes.是悄悄按住其中一个孔 If you cover this hole, you get a blue drink.按住此孔 倒出的是蓝色液体 If you cover this hole, you get a yellow drink.按住这个孔 倒出的是黄色液体 If you cover no holes, you get a green drink.哪个都不按 倒出的便是绿色液体 So three drinks in total.总共有三种液体 Though, actually no, four drinks.但其实是四种 If you cover both holes, you get the null drink.因为两个孔都按住就没有液体流出了 But how does it work?它的原理是什么呢? Well, you know me, if I want to describe为了解释 how a hydrodynamic mechanism works,水动力结构的运作机制 I like to make a transparent 2D version of it.我一般会制作一个透明2D模型 I’ll put a playlist of those videos我会在描述页面里 in the card and the description.放上这些2D模型视频的播放列表 First, I needed to figure out首先 我们要弄明白 what was going on inside the teapot,茶壶的内部构造 and a bit like with the gluggle jug,它的内部有点像魔术罐 the only really sensible way to do that唯一可行的方法就是 was to hit it with a hammer.用锤子把它砸开 So you can see there are two chambers here, side by side,我们可以看到这里面有两个并排的空室 and they both lead up to the spout.都通往壶口 Additionally, one chamber leads up to this hole,此外 其中一个空室连着这个孔 the other chamber leads to this hole.另一个连着这一个 For the 2D version, I don’t want to put them side by side,在2D模型中它们不是处于并排的位置 ’cause then it wouldn’t be 2D, but I feel like因为那样就不是2D了 但我觉得 I can put them top to bottom and it should still work.可以调整为上下排列 功能应该不会改变 And here it is.就像这样 So if I want a blue drink, I cover this hole.若想要蓝色液体 就按住这个孔 If I want a yellow drink, I cover this hole.想要黄色液体 按这个孔 And if I want a green drink, I cover neither of the holes.想要绿色液体则两个孔都不按 And for completeness, here’s the null drink.为了演示得完整些 也看看无法倒出液体的情况 Similarly, I could have a black coffee or I could have milk,同理 它既可以倒出黑咖啡也可以倒出牛奶 or I could have a milky coffee.还可以倒出奶咖 So that’s how it works, but why does it work?这便是它的运作机制 但其中的原理是什么呢? Why is it that putting your finger over different holes为什么按住不同的孔 causes different liquids to flow out?便会有不同的液体流出来呢? What it comes down to is surface tension.这一切 归根结底是表面张力造成的 it’s similar to this demonstration you might’ve seen before.你可能看过下面这个演示 里面的原理是类似 Look, I can pour water from this bottle,看 我们可以从瓶子里倒出水 but if I turn the bottle upside down, no water pours out.但把瓶子倒置后水便无法流出 The trick is that there’s a gauze这是由于这里有张网纱 covering the opening of the bottle,盖住了瓶口 so when I pour it like this, water can flow out因此可以这样倒 水就会流出来 and air can flow in, but when I turn the bottle upside down,空气也可以进入瓶内 但把瓶子倒置后 for water to flow out, air would need to flow in水要流出 空气就得流入 and for air to flow in,空气要流入的话 surface tension would need to be broken.就需要打破表面张力 Here’s another example where instead of a gauze,再看一个不用网纱的例子 there’s a small hole.这里有个小孔 The hole is actually big enough to push a straw up into,孔的大小可以插入一根吸管 and it floats to the top of the bottle.插入吸管后 它会漂浮起来 It’s a really cool trick.这是个很酷的把戏 You know, strictly speaking, ultimately,其实严格来说 归根到底 it’s not surface tension That’s keeping the liquid in place.并非是表面张力 而是气压 It’s air pressure.让水无法流出 The assassin’s teapot and these bottle tricks刺客茶壶和这个瓶子魔术 wouldn’t work in a vacuum.在真空里就不奏效了 So the reason the liquid doesn’t fall out所以用大拇指按住孔 of the assassin’s teapot when you have your thumb液体就无法流出茶壶 over the hole is because the atmosphere is pushing on it.是因为大气压压迫了水流 Atmospheric pressure is holding the liquid in place.将液体困在了壶内 And that’s counter-intuitive.这看起来违背常理 You’d think, well, the real explanation大家可能会认为 应该是 is that if the liquid did fall out a little bit,若液体流出一点 it would create a vacuum and the vacuum就会产生真空 would pull the liquid back in.真空会将液体拉回壶内 But there is no pulling force,但实际上并没有什么拉力 there’s only pushing force from the atmosphere.只有大气压的推力 It’s like when you suck on a straw.就像吸吸管时 It’s not the suction that’s pulling the liquid up the straw.并非是吸力让液体在吸管中上升 It’s the atmosphere pushing the liquid up the straw.而是大气压推着液体升到吸管上部 And that’s really counter-intuitive because you feel like,你觉得它违背常理 well, look, that’s me doing the work.因为现在不是你亲自在尝试 I am sucking on the straw.而是我 在吸这根吸管 I’m pulling the liquid up with my lungs.是我在用肺把液体吸上来 At this point, I want to go off on a bit of a tangent说到这 我想偏个题 and talk about a type of pedantry谈谈 一种我并不觉得 that I think isn’t always helpful.始终有益的学究做派 Like imagine you say, “I’m sucking liquid up a straw now.”比如你说:“我正用吸管吸液体” I mean, it’s a weird thing to say out loud,当然 大声讲这个会很怪异 but hypothetically, and then an annoying physicist但假设有个烦人的物理学家 comes along and says, “Well, technically过来说:“实际上 you’re not sucking water up a straw.不是你将水吸上来 It’s the atmosphere pushing it up the straw.”而是气压将水推上来的” And then in the next breath, that physicist might go on紧接着物理学家可能又开始 to talk about the flow of positively charged holes跟你讲半导体里 in a semiconductor.带正电的空穴的流动 Well, holes don’t flow and a hole can’t have charge.好吧 其实空穴无法流动 也不可能带电 So why is it okay to talk about但为什么“带正电的空穴的流动” the flow of positively charged holes?这个说法没错呢? What the reason it’s okay is because it’s useful.之所以没错 是因为它有用 But I would also argue that it’s useful但我同样会辩解 说 to talk about a suction force.那谈论“吸力”也有用 so long as you keep the underlying physics in mind,只要记住背后的物理原理 you should be okay.就可以了 Like for example, you can’t just举个例子 你不可能 increase a suction force indefinitely.一直增加吸力 Eventually when you get to about a hundred kilopascals,当你最终吸到100千帕斯卡左右时 it stops working because you’ve run out吸力就无法继续增加了 因为 of atmospheric pressure, the thing that’s really真正使液体上升的大气压 doing the work underneath.已经用尽了 Similarly, I think it should be all right同样 我们再来看看 to talk about the flow of the cold.寒气的流动 Like if I put an ice cube in my drink,若将冰块放到饮料里 the cold flows from the ice cube into the drink.冰块融化 寒气释放到饮料中 Of course that’s not really what’s happening,当然 事实并非如此 the warmth from the drink is flowing into the ice cube其实是饮料中的热量进入到了冰块中 and so it gets colder, but it’s useful to talk about饮料因此变冰 但只要能帮助你弄清背后的物理原理 the flow of cold, again, so long as you understand说成“寒气释放”也无妨 the underlying physics, like you can’t just例如你不能 keep pumping cold into something because eventually,只是一直向某一物体传递寒气 you reach absolute zero.因为最终 物体会达到绝对零度 By the way, these animations are from a video I made顺便说下 这些动画均来自我制作的视频 about how all LEDs are secretly solar panels主要解释了为何发光二极管其实是太阳能电池板 and all solar panels are secretly LEDs.太阳能电池板其实也是发光二极管 The link’s in the card and in the description.视频链接在播放列表和描述页面里 Okay, tangent over.现在回归正题 The point is, we all know that for the water to get out,关键是我们都明白想要水流出 air needs to be able get in and with your finger就需要有空气流入 手离开孔 off the hole, well, air can get in at the top,空气便可以自顶部流入 but if you cover over the hole,但若按住孔 the only way for the air to get in is through the spout,空气就只能从壶口进入 and that’s where surface tension comes in.壶口处也就形成了表面张力 Surface tension acts to minimize surface area.表面张力能够减小表面积 You might think, well, one way for the water to get out你可能在想 若空气能溜进壶口 is if the air can sneak past it on the way,水就能流出了 but what would that look like?但这会变成什么样呢? Well, it might look a bit like this.可能会有点儿像这样: You’ve got a drip of water starting on one side.一开始 一边是一滴水 And on the other side, you’ve got a bubble of air forming,而另一边则是气泡 but see how that increases the surface area of the water.水的表面积便由此增大 And because surface tension acts to decrease因为表面张力主要用于减小表面积 the surface area, that’s not energetically favorable所以空气流入壶口的假设不具有能量优势 and so you don’t get this bubbling effect,因此 也并不会有这种气泡出现 and instead the liquid is trapped inside the chamber.相反地 液体会留在壶中 This is also the principle behind a magic trick, by the way,这也是一种魔术背后的原理 sometimes called inexhaustible bottle, or think a drink.人们有时称之为“取之不尽的瓶子”或“饮料闪现” It’s usually a bit more elaborate.这种瓶子的构造更复杂些 It’ll have more chambers and different options for drinks,有更多空室 可以倒出更多种饮料 but anyway, you can read all about it in my kids book,不过不管怎样 你都可以从我写的儿童读物 “Science is Magic,” available from all good bookstores.《科学即魔术》里读到这些 各大书店都能买到噢
  • 2022-06-27繁盛宇宙中的外星生物Imagine you’re an interstellar traveler.假如你是个星际旅行者 What sorts of alien life might you find out there in the universe?在宇宙中你会发现什么样的外星生命呢? It’s interesting to speculate on how life might evolve in the depths of a planet covered by oceans,推测生命在被海洋覆盖的行星深处 or the skies of a world with an atmosphere teeming with floating life.或是在大气中充满漂浮生物的星球的天空中如何进化是件趣事 Perhaps one day, humanity will be able to set out into the universe,或许有一天 人类能够深入宇宙 and document these unfamiliar worlds first-hand.并亲手记录这些未知星球的信息 This concept is explored in great scientific detail in The Teeming Universe,这一观念在科幻作家和艺术家Christian Cline的星际野外指南 an interstellar field guide by speculative author and artist Christian Cline《繁盛的宇宙》一书中进行了详细的科学探讨 The book, which I have a link to down below, explores how alien life might evolve这本书我在下面有一个链接 它探讨了外星生命 on various types of planets much different from our own.可能如何在与我们大相径庭的各种类型的星球上进化 So, for this entry into the archive,因此 为了进入这个档案 we’ll be joining a scientific vessel on a journey into the beyond我们将加入一艘科学考察船 踏上一段通往远方的旅程 — and will explore just some of the worlds that Cline covers in his field guide.探索一些Cline在他的星际野外指南中涵盖的星球 Several million light-years from Earth,我们着陆的第一颗虚构星球 the first fictional planet we’re touching down on…距离地球几百万光年 -doesn’t look like much.看上去没什么特别的 This is planet Menir, a world of ice and rock这是被冰雪和岩层覆盖的Menir星球 with a diminished atmosphere and high levels of ultraviolet radiation.这里大气层稀薄 紫外线辐射强 Stepping out onto the surface, it seems like there isn’t any life here.踏上它的地表 看上去没有什么生命存在 But that’s because to find life on Menir那是因为要在这个星球发现生命 you have to look under a microscope.需要借助显微镜 That’s right, the first alien life we’ve found is a kind of bacteria.没错 我们发现的第一种外星生物是一种细菌 It might seem disappointing,看上去也许有些扫兴 and there be will much larger aliens to come later in this entry,后面的旅程中会有一些大得多的外星生物 but even discovering microscopic life on an exoplanet但即使是在太阳系外行星上发现微观生命 would be a huge movement in science.也会是科学上的一大进步 And just because these lifeforms look like Earth microorganisms to the untrained eye,虽然这些生命形式在外行人看来像地球微生物 it doesn’t mean they’re the same.但并不意味着它们是一样的 Called Menirophiles by the artist,它被作者称为Menirophiles he imagines their unique purplish-pink color他设想它们独特的紫粉色 helps them reflect excess radiation有助于反射过量的紫外线 and because they contain hydrogen-peroxide within various organelles instead of water并且它们各种细胞器内含有过氧化氢而不是水 they don’t freeze.因此不会被冻住 While such a mixture would be deadly to Earth bacteria虽然过氧化氢对地球上的细菌是致命的 menirophiles are protected from the harsh effects by silicon in their molecular structure.但menirophiles分子结构中含有的硅保护它们免受伤害 So, while the life on the desolate Menir may be tiny,所以尽管荒凉的Menir上的生物也许微小 it’s exceptionally resilient.却有很强的适应力 But the time has come to leave this exoplanet到了离开这个系外星球 and head to world where life gets a little bigger…前往有着大一点生命体的世界的时候 At first glance, our next planet — Ateria — appears far more Earth-like.乍一看 我们的下一个行星Ateria似乎与地球相像得多 With a protective atmosphere and liquid oceans,由于有保护性的大气层和液态海洋 Ateria offers a much better opportunity to find complex alien life.Ateria为发现复杂的外星生命提供了更好的机会 Touching down on the surface, it’s a beautiful foggy day.在这里着陆的时候是个美丽的雾天 Out of the mist rise grand plant like structures,建筑物般高大的植物从薄雾中耸立出来 and the air is filled with the buzzing of animals.空气中充满了动物的喧闹声 Yet we’ll find Ateria is much different from earth in one critical way…然而 我们会发现Ateria在一个关键方面与地球有很大的不同 its seasons.它的季节 On earth, seasonal change happens gradually due to earth’s axial tilt,在地球上 由于地球轴向倾斜 季节变化是逐渐发生的 with most animals having numerous strategies to adapt to the predictable changes.大多数动物都有很多策略来适应这种可预测的变化 But due to a past asteroid impact但由于曾经遭受过小行星撞击 Ateria has a wildly elliptical orbit:Ateria的运行轨道是狭长的椭圆形 meaning it moves close to its sun for some of its orbit意味着它的部分轨道靠近它的恒星 and far out into the cold of space for the rest.其余部分远离恒星进入寒冷的太空 This means the seasons on Ateria are truly extreme…这使得Ateria星球上的季节很极端 and life on this planet has had to get creative.在这里生活的生物必须有创新性 Beginning with plants, we might spot Strungs, which possess a bright red tint从植物开始 我们会看到Strungs 它有淡淡的亮红色 to get the most out of the sun’s slightly dimmer light.可以最大限度的利用微弱的光线 During winters when the environment cools,在冬季 当环境变冷时 Strungs partially hollow bark retains insulating air,Strungs部分中空的树皮会保留隔热空气 allowing for extra heat protection.使额外的热量保护成为可能 But other organisms — like the Fisher Crame但其它生物 例如我们旅途中 the first animal we’ve encountered on our voyage见到的第一个动物Fisher Crame have a different strategy to survive the seasonal changes.有不同的策略在季节变化中生存 They might look someone like insects,Fisher Crames看起来像昆虫 but Fisher Crames are far larger,但比昆虫要大得多 with wingspans of four feet, or 1.2 meters.其翼展可达4英尺 即1.2米 To outsmart the cold, these creatures simply die after laying eggs,为了战胜寒冷 这些生物索性在产卵后死去 which a new generation emerges from when temperatures rise again当温度再次上升时 新一代就会从卵中诞生 to start the cycle anew.开始新的循环 Another insect-like creature , the Tripperhog,另一种类似昆虫的生物Tripperhog has the more familiar strategy of hibernating during the long winter,用我们更熟悉的冬眠策略过冬 with their thick shells camouflaging them and protecting them from harm.它们用厚重的壳伪装 保护自己免受伤害 Another clever solution.是个不错的办法 Ateria is a fascinating and extreme world,Ateria是个迷人和极端的地方 but we must look to the horizon once again,但我们必须再次远眺 and see how much more incredible alien life can get.寻找更多不可思议的外星生物 The next stop on our journey is a massive fictional planet called Toreya.旅程的下一站是一个巨大的虚构星球Toreya The brilliant blue of the planet comes from the fact它的亮蓝色是由于 that 99% of the surface is comprised of an incredible planetwide ocean.表面的99%都是由浩瀚的海洋组成的 Life in our own oceans can already be so alien地球的海洋生命已经如此怪异 so you can imagine what’s under the waves of these endless waters…所以可以想象 在这无边的海洋里的生命又是如何 The region closest to the surface is called The Pelagic Zone —最接近海面的区域被称为远洋区 and contains entire ecosystems founded on towering colonies of kelp-like plants.它包含了建立在高大的海藻状植物群上的整个生态系统 Nicknamed ‘Heavenkelp,’ these plants can grow up to an astonishing 750 feet,这些被称为“天藻”的植物可以长到惊人的750英尺 or 228 meters in length — almost like underwater trees.即228米长 相当于水下的树 Among the leaves, aquatic life such as the fish-like pelagonareans水生生物如形似鱼的pelagonareans seek shelter and food.在树叶间寻求庇护和食物 Some fish on Earth live in undersea forests of kelp or seaweed for similar reasons.出于类似的原因 地球上的一些鱼类也生活在海藻或海草的海底森林中 Pelagonareans, or Pelegs for short, are a highly diverse groupPelagonarean简称Pelegs是一个已经进化到 that have evolved to fill all manner of underwater niches.占据了各种水下生态位高度多样化的群体 The incredible diversity of the PelegsPelegs令人难以置信的多样性 makes the oceans of Toreya a teeming aquatic wilderness,使Toreya的海洋成为一片拥挤的水生荒野 much like the richest areas of Earth’s oceans.与地球海洋内最富饶的区域很相似 The artist imagines that one species of Pelegs作者设想有一种Plege — the gallant gulls — can even leave the water altogether,“勇敢的海鸥”可以完全离开水面 as they’ve evolved powered flight.因为它们进化出动力飞行 Due to their aquatic ancestry, however,然而 由于它们水生的天性 they still need to occasionally dive back underwater to breathe.仍然需要偶尔潜入水下呼吸 But the Pelegs aren’t the only lifeforms that lurk below the waves.但Pelegs并不是潜伏在海浪下的唯一生命形式 Further down, in the twilight of the Bathypelagic Zone再往下 在深海区域的微光中 you can find various translucent or bioluminescent species你可以看到各种各样的半透明的或者发光的物种 feeding on floating pieces of organic matter… or on each other.以漂浮的有机物为食……或者彼此捕食 And it’s here where the largest organisms on Toreya dwell: the Anoom这是在Toreya居住的最大生物体: Anoom — the most gigantic creatures we’ve encountered on our journey so far.它是目前为止我们在旅途中遇到的最大生物 They’re able to reach a staggering 250 feet, or 72 meters in length由于Toreya的海洋之广大 它们的身长 due to the vastness of the planet’s oceans,能达到惊人的250英尺(72米)长 which the Anoom navigate on an enormous transparent sail.它们乘着巨大的透明帆在海上航行 Curiously, the Anoom are composed of vast colonies of jellyfish-like invertebrates,奇怪的是 Anoom是由巨大的水母状无脊椎动物群组成的 which work together as a single giant lifeform.它们共同组成了一个巨大的生命体 And at the bottom of this planet-wide ocean在这片广阔海洋的底部 you can find the Abyssopelagic zone,你可以发现深渊带 where ghostly, pale-grey species swim through the dark在那里 幽灵般的淡灰色物种在黑暗中游动 in the absence of sunlight,由于缺乏阳光 many lifeforms in the abyss survive off a chemical soup supplied by hydrothermal vents,深渊带的许多生物 依靠深海热泉提供的化学汤状物生存 an extreme form of survival that also occurs in our own oceans这种极端的生存方式也出现在我们的海洋中 — proving life can take hold almost anywhere.证明生命几乎可以在任何地方生存 And the next imaginary planet on our interstellar journey is no exception.我们星际旅行中的下一个科幻星球也是如此 At 64% of earth’s mass,Yulene是我们迄今为止访问的最小的星球 Yulene is the smallest planet we’ve visited yet.质量只有地球的64% its gravity therefore is so low因为它的重力如此小 it’s on the very edge of the minimum for planetary habitability —处于行星宜居性的最低限度的边缘 which has had a fascinating affect on the planet’s native life.这对它的原生生物产生了奇妙的影响 Much of Yulene’s surface is locked in permanent ice caps,Yulene的大部分表面都被冰冠永久覆盖 as the low gravity has resulted in a thin atmosphere that retains little heat.这是因为低重力导致了大气稀薄 无法保存一点热量 While some forms of life venture into these frozen wastes,尽管一些物种冒险进入这些冰冻的荒原 most of the planet’s organisms live on the warmer equatorial tundra.但星球上的大多数生物生活在更温暖的赤道苔原上 Here, for the first time in our interstellar voyage,在这里 我们在星际航行中第一次 we can spot trees which are quite similar to those on earth.看见了与地球上非常相似的树木 Similar doesn’t mean the same, however,相似并不意味着相同 and upon closer inspection of their leaves,仔细检查它们的叶子 you can spot some key differences.你可以发现一些关键的区别 Due to a higher presence of blue visible light on Yulene,由于Yulene上有更多的蓝色可见光 leaves have evolved to use not chlorophyll,树叶已经进化到不利用叶绿素 but the yellow pigment xanthophyll for photosynthesis.而是利用黄色色素叶黄素进行光合作用 Above the yellow foliage, you can spot the magnificent Clerei在黄叶上方 你可以看到巨大的Clerei flying animals similar to birds or pterosaurs.一种类似于鸟类或翼龙的飞行动物 These low-gravity fliers have wingspans of nearly 40 feet, or 12 meters,这些低重力飞行生物的翼展接近40英尺 即12米 which they use to soar on mountain thermals它们利用翼展在山上的热气流中翱翔 that help them achieve lift-off despite the thin atmosphere.热气流有助于它们在稀薄的大气中起飞 After mating, Clerei build nests in the branches of Yulene’s trees交配后 Clerei在Yulene的树枝上筑巢 raising their young in pairs like many species of birds.像许多鸟类一样成双成对抚养后代 And their newborn babies are called Cerilets,新出生的幼鸟称作Cerilets which is one of my favorite details.这是我最喜欢的细节之一 Clerei typically feed on animals like the Cobbleback Trate,Clerei通常以Cobbleback Trate之类的动物为食 an aquatic creature that gets its name from a pattern of stone-colored markingsCobbleback Trate是一种水生生物 其名字来源于它身上石头颜色的斑纹图案 that help camouflage it from predators gliding overhead.这种斑纹帮助它伪装 躲避头顶上滑翔的捕食者 To lay their eggs, the Cobbleback Trate, like many freshwater Earth fish,为了产卵 Cobbleback Trate像许多地球淡水鱼类一样 must make a trying voyage必须进行一次艰难的航行 upstream to the frigid regions where predators are scarce.逆流而上到掠食者稀少的寒冷地区 One creature that doesn’t have to worry about predators,然而有一种动物不需要担心捕食者 however, is the armored Sisobe,那就是全副武装的Sisobe low-gravity grazers that can grow up to 20 ft, or 6 meters in length.这种低重力食草动物可以长到20英尺 即6米长 From the edge of the tundra to the continental deserts,从苔原的边缘到大陆上的沙漠 you can find these shaggy giants,都可以看到这些皮毛粗糙的庞然大物 which move in great herds not unlike Earth bison.它们成群结队地活动 就像地球上的野牛一样 And as the sun sets on Yulene,当其恒星在Yulene落山时 many plants let off a brilliant glow to attract pollinating species.许多植物发出明亮的光芒来吸引授粉物种 It’s a dazzling display,这是一场令人眼花缭乱的展示 but the time is come to continue our expedition.但是到了继续我们的探险的时候了 And the next imagined world is perhaps the most extreme so far.而下一个假想星球可能是目前为止最极端的 Borold is a planet that closely orbits a red dwarf star,Borold是一颗紧绕一颗红矮星运行的行星 only 20% the size of our sun, and far cooler红矮星大小只有太阳的20% 温度也低得多 Borold is also tidally locked,Borold 也是被潮汐力锁定的星球 with one side of the planet perpetually facing the sun in endless day,它的一边在无尽的白天永远面对着太阳 and the other trapped in endless night.而另一边被困在无尽的夜晚 Yet despite the harshness of Borold尽管Borold的环境很恶劣 there is life upon this rock.在这块岩石上还是有生命存在的 In the less extreme twilight region between the dark and light sections of the planet,在行星的亮部和暗部之间不太极端的昏暗区域 you can find the Borold Stars.你可以发现一种生物叫Borold Star The largest animals on this planet’s surface它们是这个星球上最大的动物 these creatures can grow up to 30 ft, or 9 meters long.这些生物可以长到30英尺 即9米长 Since the gravity on this planet is almost 3 times that of earth.由于这个星球的重力几乎是地球的3倍 These Stars creep slowly across the ground —这些动物几乎像巨大的陆地海星 almost like giant terrestrial starfish.在地面上缓慢爬行 The real challenge for Borold Stars, however, is food and water.然而Borold Stars面临的真正挑战是食物和水 Unable to hunt due to their top speed being one mile,由于它们的最高时速只有一英里 即1.6公里 or 1.6 kilometers per hour,所以无法捕猎 Borold Stars simply crawl over anything edibleBorold Stars仅仅爬过任何可食用的东西 and crush it under their body.用身体将它们压扁 And when they find water,但当它们发现水源 these unusual creatures can drink hundreds of gallons at a time.这些不寻常的生物一次可以喝下数百加仑 Borold Stars aren’t alone on this rock, however.然而Borold Stars并不孤单 There are also plants… just not plants as we know them.还有植物作伴 只是不像我们熟知的植物那样 These are Vleian Ojur, which look like jagged, tall stones,这些看起来像锯齿状的高大石头叫Vleian Ojur but are actually cone-shaped photosynthetic lifeforms most analogous to Earth trees.但实际上是与地球上的树木非常相似的锥状光合生物 Their design helps protect them from the planet’s brutal winds,它们的外形有助于保护它们免受星球上狂风的侵袭 which are the result of the extreme temperature gradients produced by the planet’s tidal lock.狂风是地球潮汐锁定产生的极端温度变化率导致的 Our final Borold organism, however,然而 我们要讲的最后一种生物 can take advantage of these perpetual winds to achieve lift-off.可以利用这些无休止的风来实现飞升 You might not expect to find creatures on a world with such crushing gravity,你可能没指望在重力如此大的星球找到会飞的生物 Borold Kites are scavengers that let these currents carry them to their next meal.Borold Kite就是凭借风寻找食物的食腐动物 Unique, Certainly,奇才? 那是当然 but even more fantastical lifeforms might be waiting on the final stop of our journey.但更奇妙的生物可能正等在我们旅程的最后一站 The last fictional planet we’ll be visiting is also the largest of them all.我们将要访问的最后一个虚构星球也是其中最大的一个 A world somewhere between a terrestrial planet and a gas giant,Hurcelion是一个介于类地行星和气体巨星之间的世界 Hurcelion has a thick atmosphere divided into layered ecosystems,它有分成了多层次生态系统的厚厚的大气层 almost like an aerial ocean.几乎就像空中的海洋 And it is in this atmosphere正是在这种大气层中 where we’ll find some of the most awe-inspiring life in all the cosmos.我们能找到宇宙中最令人惊叹的生命 In the stratosphere, ballon-like animals float on sacs of internal hydrogen,在平流层 气球状动物通过体内的氢气囊漂浮在空中 steering themselves through the air on specialized fins.用特制的鳍在空气中航行 Many of these animals feed on green clouds of areofoliage,它们中的许多以绿色云状的areofoliage为食 groups of small floating plants held aloft by the windareofoliage是一堆堆随风漂浮的小植物 which contribute to the high oxygen levels in Hurcelion’s atmosphere.它们导致了Hurcelion大气中的高含氧量 And feeding on the herbivores are Speldos: airborne predators以这些食草动物为食的是空中掠食者Speldos: which despite being twice as long as a school bus, are quite agile.尽管它们的身长是校车的两倍 却非常敏捷 Speldos lack jaws, but their gaping mouths are filled with teeth,Speldos没有下颚 但它们张大的嘴里却长满了牙齿 so to hunt they simply ram into their prey.所以要捕猎的话 它们直接撞向猎物就可以了 But the Speldos aren’t the true titans of these skies,但Speldos并不是这片天空中真正的大块头 Oones are the largest animal we’ve found on this expedition,Oones是我们在这次探险中看到的最大的动物 at over three times the size of a blue whale.体型是蓝鲸的三倍多 Indeed, Oones are more than just singular lifeforms,实际上 Oones不仅仅是单一的生命体 and incorporate dozens of symbiotic species into their bodies.在它们的身体里融合了几十种共生物种 Oone mites are among the most importantOone 螨虫是其中最重要的 as they act as the colony’s guardians.因为它们是群体的守护者 While normally docile, they become fierce protectors虽然平时温顺 但当它们称之为家园的那个 Oone 受到威胁时 when the Oone they call their home is threatened.它们就变成了凶猛的保护者 Sometimes, however, an Oone passes away然而有时一个Oone会死亡 and falls through the atmosphere to Hurcelion’s surface,穿过大气层落到Hurcelion的表面 in a striking event known as an Oonefall.这一惊人的事件被称为“Oonefall” Below the calmer upper-atmosphere,在较平静的上层大气下面 the surface of Hurcelion is a volcanic, stormy wastelandHurcelion的表面是一片火山肆虐的荒原 — and one of the most extreme regions glimpsed so far.也是迄今为止我们所看到的最极端的地区之一 Yet even here there is life,但即使在这里也有生命 like the tiny Praglerworms,比如微小的 Praglerworms which you can spot illuminating the dark with their bioluminescent displays.你能看到它们用生物发光照亮黑暗 these humble organisms prove once for all这些不起眼的生物完全证明 that life can take advantage of even the most extreme scenarios生物可以利用哪怕是最极端的情况 Although our journey through the cosmos is over for now,虽然我们在宇宙中的旅程暂时结束了 Christian Cline’s book The Teeming Universe但Christian Cline的书《繁盛的宇宙》中 contains many more incredible speculative worlds and alien creatures,包含了更多令人难以置信的新奇世界和外星生物 I encourage you to check out the link to it below我建议你查看下面的链接 I’ve also included a link in the description to Astrovitae,我还在下面加入了Astrovitae的链接 a relatively new speculative biology magazine这是一本比较新的推理性生物学杂志 you can read online for free.你可以线上免费阅读它 The Teeming Universe was recently featured there,《繁盛的宇宙》是近期的主要内容 and they’ve got a lot of other cool stuff too,但是里面也有许多其它很酷的内容 so I wanted to spread the word to fans of the genre.所以我想把这个消息传给这一类的粉丝 And as always, thanks for watching.感谢您的收看 If you enjoyed this entry,如果你喜欢本次旅行 please lend your support and like, subscribe,请给予支持 点赞 订阅 and hit the notification icon to stay up to date on all things Curious.点击通知图标 了解Curious所有的最新动态 See you in the next video.下期再见!
  • 2022-06-27如果月球爆炸了会怎么样?“Oh, did you see that?”哦 你看见了吗 “Oh my god.”我的天啊 Is it a meteor shower?那是流星雨吗 Space debris?太空碎片? No, it’s something much, much worse.不 是更 更 更糟糕的东西 Our nearest neighbor我们最近的邻居 is a full Moon no more.不再是一个完整的月球了 The Moon exploded and splintered月球被炸裂成 into millions of fragments.无数个碎片 Enormous lunar rocks are hurtling toward Earth.巨大的月球岩石块正冲向地球 Could this wipe us out of the face of the planet月球的爆炸会让我们荡然无存吗? How could the Moon explode in the first place最初月球是如何被炸成碎片的呢? And if we do survive还有 如果我们存活下来 How would losing the Moon change our lives we know it失去月球给现在的生活会带来什么变化? This is WHAT IF, and here’s what would happen这里是《自然无常》 接下来将为你讲述 if the Moon exploded?月球爆炸的话将会发生什么? Okay, so how on earth did the Moon blow up?那么 月球究竟是怎样爆炸的呢? A blast mining operation gone wrong?爆炸式采矿作业出错? A nuclear blast?发生核爆炸? A collision with a rogue planet?与流浪行星相撞? Whatever caused this catastrophe,无论是什么造成这个灾难 you’d have to be packing你都必须装备 some serious firepower to blow up the Moon.一些强力的火药来炸掉月球 “Guns, lots of guns.”我要枪 很多枪 The largest nuclear bomb ever built,曾经制造的最大原子弹 the Tsar Bomba,沙皇炸弹 had the energy of over 57 million tons of TNT.拥有超5700万吨TNT炸药的威力 Think that’s strong enough?觉得那足够强劲了? It’s just a drop in the ocean与炸掉月球 compared to the amount of force总计所需的火力相比 you’d need to blow up the Moon.那只不过是沧海一粟 You’d need the power of over 600 billion Tsar Bombas你需要 超过六亿个沙皇炸弹的火药威力 to destroy the Moon.才能毁灭月球 With anything less than that,要是火力不及的话 the Moon would just crack into pieces月球只会被炸成碎片 and its gravity would pull it back together again.然后月球的引力会吸引碎片 重新聚拢起来 But if someone,但是 如果有人 or something或者某个东西 managed to explode the Moon,设法炸掉月球 it would spell bad news for us.那将给我们招致灾难 The Moon debris would scatter月球的碎片会分散在 across the Solar System.整个太阳系 Some into the abyss of outer space,有些碎片会飘进外太空的深渊里 and some headed straight for Earth.有些会直接冲向地球 Earth’s gravitational pull would地球的万有引力将会 immediately start to attract the Moon rocks.立即吸引月球的碎石 As the Moon’s remains start to pick up speed,随着月球的残骸开始加快速度 they would come crashing down into the atmosphere.他们会猛冲直撞 进入大气层 Luckily, most of the smaller debris幸运的是 大多数小碎石 would burn up before it reaches us.在抵达地球前会在大气层中燃烧殆尽 Any larger pieces that got through任何穿过大气层的大碎石 would be traveling much slower会比类似大小的行星 than a similar-sized asteroid.移动得更慢 The damage they’d cause他们所引起的破坏力 wouldn’t amount to much.并不会很严重 But, is it just me,但只有我意识到 or is it getting a little hot in here?这里变得有点热吗? The Moon chunks aren’t causing much damage.月球的石块没有造成很大的破坏 But the endless barrage of debris on our atmosphere would但是接二连三的碎石 一齐撞向大气层 start to heat up the Earth.会使地球变热 The whole world would start to get hotter, and hotter,全世界都将变得 越来越热 eventually getting to the point of incinerating all life.最后 所有的生命 都将被烧成灰烬 Talk about a bad way to go.说一个糟糕的事情 Oh, and if you’re thinking about哦 如果你正想着 trying to evacuate Earth,尝试逃离地球 you better do it as soon as possible.你最好尽早采取行动 The Moon debris, combined with all the satellites would destroy in space,月球碎石并同所有卫星 会在太空中毁灭 would make any trip out nearly impossible.这使任何太空航行不再成为可能 But what if you did manage to “get out of Dodge,”但要是你真的设法 “避而远之” or hunker down in the deepest parts of the Earth?或低调蜷留在地球深处 会怎样呢? What would life be like in the aftermath?灾难之后 我们的世界会变成什么样呢? Well, for some of us,对一些人来说 it wouldn’t get any cooler.并不会感觉到多冷 The Moon helps stabilize the Earth’s axial tilt.月球能使地轴倾斜度保持稳定 It’s what gives us seasons.因此 我们有了四季 With a new tilt, some parts of the Earth新的倾斜度不同 地球上的某些部分 could be constantly exposed to the Sun. 可能不断受到太阳照射 In the worst case,最糟糕的情况是 the polar regions could start rapidly melting,两极冰川可能会迅速融化 raising sea levels,海平面上升 and drowning out parts of the world.世界上的某些地方将被淹没 As the debris settles,当碎石定置下来 the skies could look a little different.天空的样子就会有点不同 The remaining Moon rock剩下的月球岩石 might cluster around the Earth可能聚集在地球周围 forming a giant ring, like Saturn.和土星一样 会形成一个大光环 But don’t stop and stare too long,但不要驻足凝视许久 every once in a while, some of the debris could rain down onto the Earth.有时候 有些碎石会如雨点般降落到地球 Over billions of years, the Moon’s gravitational pull 亿万多年间 月球的万有引力 slowed down the Earth’s rotation,将减慢地球自转速度 giving us our 24 hour days.因此一天有24小时 Without the Moon,没有月球 the Earth would start to rotate地球会旋转得 faster and faster.越来越快 We’d have shorter days,一天将会缩短 and stronger winds.风变大 Birds and insects would鸟类和昆虫将 have a tough time surviving the harsh winds.很难在强风中生存 Not only that,不仅如此 ocean tides would start to die down海潮将开始平息成 into tiny little waves.小小的海浪 The Moon’s gravity月球的重力 helps create tides on Earth.有助于地球形成海潮 Bummed out that you can’t rip some gnarly waves anymore?很遗憾 你再也不能在那些很炫的波浪上冲浪了 Well dude,好吧 朋友 there will be a much bigger problem.还有一个更大的难题 It would wipe out all of the sea creatures that rely on the依赖潮汐与洋流而生存的各类海洋生物 tides and ocean currents for survival.将会被彻底消灭 Our whole world would be整个世界真的将会 literally flipped upside down.变成一个完全不同的世界 The Earth would burn up,地球会被烧毁 our days would be shorter,一天会变得更短 and the Moon wouldn’t be there也没有月亮 to light up the night sky.照亮夜空 Now that we know how devastating既然我们知道了 it would be if the Moon exploded,月球爆炸带来的毁灭性是怎样的 what if instead of having no Moon,如果不是月球消失 而是出现两个 we had two?将会怎么样呢? Well, that’s a story for another WHAT IF.另一期《自然无常》咱们故事继续
  • 2022-06-27黑死病:历史上最严重的流行病This video was made possible by CuriosityStream.本期视频由CuriosityStream赞助播出 When you sign up at curiositystream.com/reallifelore在curiositystream.com/reallifelore注册后 you also get access to NEBULA你也可以访问NEBULA the stream video platform that ReallifeLore is a part of.它是一个流视频平台 其中也包含ReallifeLore系列 Pandemics and diseases have been a constant companion of humanity几千年来 流行病和疾病 for thousands of years.一直伴随着人类 And although they happen relatively rarely,虽然发生得相对较少 they can be tremendously destructive.但造成的破坏性巨大 And they often change society in strange and unexpected ways.并且常以奇怪又出乎意料的方式改变社会 And there is perhaps no disease that has changed大概没有什么疾病能比 the entire course of human history more than the original plague,起初的这次瘟疫更能改变整个人类历史进程 the bubonic plague.那就是黑死病 Lately originating somewhere around TianShan Mountain in central Asia,最近在中亚天山附近发现的 the bacterium Yersinia pestis, the causes of bubonic plague,鼠疫耶尔森氏菌是黑死病的起因 like relatively dormitive with only occasional outbreaks for untold millennia它相对来说处于休眠状态 几千年来只偶尔爆发 until something changed in the 6th century AD.直到公元 6 世纪发生了变化 The Byzantine Empire was at its apex of power and influence.拜占庭帝国处在权力和影响力的顶峰 She has just retaken the Italian peninsula,刚刚夺回了意大利半岛 and was close to reuniting the entire Roman empire again,并且即将再次统一整个罗马帝国 when all of a sudden, at a worst possible time,但时运不济 the bubonic plague appeared in Egypt.黑死病在埃及突然爆发 It’s not entirely clear how it got here目前还尚不明确它是如何从发源地中亚 from its origins in central Asia,传播到这里的 but the first global pandemic in human history但是无论如何 人类历史上 was about to begin anyway.第一个全球性流行病即将开始 The bubonic plague is spread by infected fleas黑死病是由生活在老鼠背上 that live on the backs of rats.被感染的跳蚤传播的 The rats stow away on ships老鼠躲在船上 and lived within close proximity to humans,而且生活在离人类很近的地方 so when the ships carried infected rats to new cities,因此 当船带着感染的老鼠到达新的城市时 the disease inevitably follows.黑死病会不可避免地随之而来 The rats eventually die被感染的老鼠最终会死亡 and the fleas that actually carry the disease实际携带病毒的跳蚤 search for new hosts and jump on humans.会寻找新的宿主并跳到人类的身上 When the fleas bite a human,当跳蚤咬到人类时 bacterium enters the body细菌会进入人体 and rapidly spreads to the human’s lymphatic system and multiplies.迅速扩散到人体的淋巴系统并繁殖 The infected person may not show any symptoms感染者在被咬后一到七天内 for one to seven days after getting bitten,可能不会出现任何症状 but they’ll eventually develop a fever, chills, vomiting但他们最终会出现发烧 发冷 呕吐的症状 and eventually the trademark appearance of smooth, painful bubos最终出现标志性的光滑 疼痛的腹股沟肿块的症状 developing out of swelled-up lymph glands它们由长在腹股沟 腋窝和脖子周围 around the groin, armpits, and the neck.肿大的淋巴腺演变而来 Gangrene of the victims’ fingers, toes, lips, and nose will eventually develop受害者的手指 脚趾 嘴唇和鼻子最终会出现坏疽 followed by extreme pain caused by the decomposition of living skin受害者还活着的时候 while the victim is still alive.皮肤被分解会给他带来极大的痛苦 Without proper medical treatment,如果没有正确的治疗 the fatality rate is between 30% and 90%被感染受害者的死亡率在 of victims who become infected.30% 到 90% 之间 And even with proper modern antibiotic care,即使有适当的现代抗生素治疗 the fatality rate still remains around 10% today.如今的死亡率仍然保持在10%左右 Obviously, the people in 6th century Europe and Middle East显然 6世纪欧洲和中东的人们 had no access to antibiotics,没有抗生素 and they didn’t even know that the rats and fleas他们甚至不知道老鼠和跳蚤是 were the cause of the pandemic,黑死病流行的罪魁祸首 so the bubonic plague exploded when ships carrying grains and infected rats因此 当载有谷物和受感染老鼠的船离开埃及 left Egypt for Constantinople,前往当时世界上最大的城市君士坦丁堡时 the biggest city in the world at the time.黑死病爆发了 The disease spread and would go on接着传播开来 to wipe out 40% of the city’s population,并将使该市 40% 的人口死亡 infecting even the emperor himself.甚至感染了皇帝本人 And as the epicenter of the Byzantine Empire,而君士坦丁堡正是拜占庭帝国的中心 the plague spread out on ships leaving for ports across the Mediterranean这使黑死病在驶往地中海港口的船上传播开来 and spread like wildfire.像野火一样蔓延 25% of all the humans living in the Eastern Mediterranean region25% 居住在东地中海地区的人 died within just a few years,在短短几年内死亡 and a tenth of the million died across the Empire and Eurasia.整个帝国和欧亚大陆有十万人死亡 The millions of death caused economic mayhem across the Empire数百万人死去让整个帝国陷入了经济混乱 who had just taken out massive loans因为他们刚刚拿出巨额贷款 to fight the wars of reconquest in Italy and the Western Mediterranean.用来打意大利和西地中海的收复战争 With millions of less people to work on farms由于在农场工作和交税的人 and pay their taxes,减少了数百万 the Empire could no longer afford to pay for future campaigns帝国再无力支付未来的战役 or even to garrison the new reconquests,甚至收复失地 and therefore the Empire entered into因此 帝国进入了一个 a long, long state of decline漫长的衰落状态 from which she would never recover.它永远无法从中恢复 The vast depopulation and economic mayhem大规模的人口减少和经济混乱 left the Byzantine Empire crippled and overextended,使拜占庭帝国陷入瘫痪和过度扩张 which allowed the Lombards the opportunity to这使伦巴第人有机会 quickly and easily takeover Northern Italy,迅速轻松地占领意大利北部 while also providing a once-in-a-lifetime opportunity同时阿拉伯人和伊斯兰教 for the Arabs and Islam也迎来了千载难逢的机会 to surge over the rest of the Empire能在帝国的其他地区大行其道 and take most of it over just a couple of generations later.并在几代人后占领其中的大部分 The first global pandemic would ultimately cause第一次全球性的瘟疫最终将导致 the death of around 50 million people or大约 5000 万人死亡 13% of all the humans in the world alive at the time即当时世界人口的13% and led to the final destruction once并导致罗马帝国 and for all of the Roman Empire,彻底毁灭 while making room for new empires同时为新的帝国 and religions to rise up in the chaos.和宗教在混乱中崛起腾出空间 The plague would finally quiet down again黑死病最终会再次平息下来 and remained relatively dormant after the mid-eight century.并在八世纪中叶之后保持相对休眠状态 Until several hundred years later,直到几百年后 when it would explode onto the world scene once again它再次在世界范围上爆发 with even more fury and death than it had ever done before.来势汹汹且致死率更高 In 1347, the bubonic plague re-emerged1347年 黑死病在克里米亚 on the world scene in Crimea再次爆发 The Republic of Genoa in Italy意大利热那亚共和国 had a trading outpost at the time in Crimea called Kaffa当时在克里米亚有一个叫做卡法的贸易前哨 which was being besieged by the Mongols.被蒙古人围攻 A few years previously,在此前的几年 the plague had broken out黑死病在中国湖北省武汉 in the Chinese province of Hubei around Wuhan附近爆发 and had killed 80% of the province’s population.并使该省80%的人口死亡 It was carried across the silk road它穿过丝绸之路 in the Mongol army’s supply and logistic lines在蒙古军队的后勤补给线上 before infecting the army that was besieging Kaffa.感染了围攻卡法的军队 After suffering from the plague for a while,遭受黑死病一段时间后 the Mongol army camped outside在城外扎营的蒙古军队 got the idea to begin catapulting their infected corpses想到可以弹射被感染的尸体到城墙另一边 over the city walls and an early attempted biological warfare.并开始尝试早期生物战 The residents of Kaffa began falling victim to the plague as well卡法的居民也开始成为黑死病的受害者 and genius merchants decided to just call it quits一些有头脑的商人们决定就此罢手 and escaped on their ships back to Italy.并乘船逃回意大利 Unknowingly to them, however,然而 他们不知道 they had brought the infected rats and fleas自己已经将被感染的老鼠和跳蚤 with them on their ships带到了他们的船上 which were the seeds that would sow而这些源头将导致 the worst pandemic ever in all of human history.人类历史上最严重的瘟疫 After the rats got off the ships in Sicily and Genoa老鼠在西西里岛和热那亚下船后 the plague exploded all across Italy黑死病在整个意大利爆发 and quickly spread along trade routes across the entire Mediterranean and Europe.并沿着整个地中海和欧洲的贸易路线迅速蔓延 So between 1347 and 1351因此 从 1347 到 1351 年 the plague ravaged most of the European continent仅仅五年间 黑死病 in just these five years.肆虐了欧洲大陆的大部分地区 It is estimated that据估计 as much as 60% of the population of the European continent died.欧洲大陆有多达 60% 的人口死亡 But some areas were hit harder than others.但有些地区受到的打击比其他地区更大 Mediterranean regions like Italy, France, and Spain意大利 法国和西班牙等地中海地区 saw as much as 75% of their populations died.有高达 75%的人口死亡 70% of England’s population died out.英格兰70%的人口死亡 60% of Norway’s and 20% of Germany’s挪威 60%的人口和德国20%的人口死亡 Paris and London both lost half of their populations.巴黎和伦敦都有一半人口死亡 And Florence lost so many people佛罗伦萨死去了太多人 that they didn’t recover their population back until the 1800s.直到19世纪才恢复 But other areas of Europe但欧洲其他地区 were almost never even touched by the plague,几乎从未受到黑死病的影响 like Poland, most of Hungary, and Belgium.例如波兰 匈牙利大部分地区和比利时 It is unclear why exactly the plague varied so greatly目前尚不清楚为什么黑死病在整个非洲大陆 in intensity across the continent.的强度差异如此之大 But within just 5 years但在短短 5 年内 6/10 people living on the continent beforehand was died.之前生活在该大陆上 6/10 的人死亡 The Black Death as it became to be known众所周知的黑死病 also heavily afflicted the Middle East,也严重影响了中东 where approximately 1/3 people died在同样的五年时间内 in that same five-year time frame as well.大约有 1/3 的人死亡 It’s believed that in just this five-year length of time人们认为 就在这五年的时间里 the bubonic plague may have killed黑死病可能已经杀死了 as many as 200 million people across Eurasia,整个欧亚大陆多达 2 亿人 which is absolutely staggering如果你记得黑死病开始之前 when you remember that the entire world population整个世界人口只有 4.75 亿 prior to the pandemic was only 475 million people.那这数字绝对令人难以置信 That means that it’s possible这意味着 that around 42% of the entire human population of the world died世界上大约 42% 的人口 within just a few years from a single disease.可能在短短几年内死于一种疾病 To put into perspective how absolutely长远来看 earth-shattering and cataclysmic it was for the time这在当时是多么的惊天动地又具灾难性 that it would be exactly like就像在今天 if a disease wiped out 3.15 billion people today一种疾病在短短几年内 in just a few years.夺走31.5 亿人的生命 It would irrevocably changed the world forever它将永远改变这个世界 just like the Black Death did in the 14th century就像 14 世纪的黑死病 and like the first plague did in the 6th century.和 6 世纪的第一次瘟疫一样 In this case在这种情况下 the Black Death wiped out most of the people living in Europe黑死病使大多数生活在欧洲的人死亡 which caused the demand for common people as laborers to skyrocket.这导致社会急需普通劳动力 The surviving peasants were in a much better position幸存下来的农民们处境变得更好 to demand higher wages and more freedom from the nobility可以向贵族要求更高的工资和更多的自由 which the nobility had to accept as reality贵族为了保持社会的运转 in order to keep the society moving.不得不接受这些现实 Wages for surviving common people went up幸存平民的工资上涨 the price of land plummeted土地价格暴跌 and peasants found new opportunities they never would have had beforehand.农民获得了百年一遇的好机会 The Black Death had begun the destruction黑死病已经开始摧毁 of serfdom and feudalism as institutions in Europe欧洲的农奴制和封建制度 and gave rise to the very beginnings of capitalism并催生了取代它的 that would replace it.资本主义开端 It would take Europe an entire two centuries欧洲需要整整两个世纪 to recover back to the population that she had才能恢复到黑死病爆发前的 prior to the eruption of the plague.人口水平 And by that point in the 1550s,到了 16 世纪 50 年代 capitalism was well on its way to taking over the continent.资本主义正席卷整个大陆 The bubonic plague would periodically flare back up之后的几个世纪里 in various places across Europe and the Middle East for centuries afterwards,黑死病周期性地在欧洲和中东多地爆发 most notably, in London in 1665 and Marseille in 1720.尤其是 1665 年的伦敦和 1720 年的马赛 But none ever became a true pandemic again但直到 1855 年在中国发生的最后一次 until the final and the most recent third great plague pandemic也就是最近的第三次瘟疫之前 of 1855 in China.没有一个能真正称为瘟疫 This time around the plague appeared in the Yunnan province of China这一次黑死病出现在中国云南省 and quickly spread across the Qing Empire并迅速从大清帝国 to the British outpost of Hong Kong,蔓延到英国前哨香港 where was transmitted aboard ships to the British colonies in India并通过船只传播到印度的英国殖民地 wreaked immense havoc.造成了巨大灾难 This third Bubonic plague pandemic would go on to这第三次黑死病大流行将继续 claim the lives of 12 million more people夺走 1200 万人的生命 mostly in India, China.其中大部分在印度和中国 But it was relatively mild everywhere else in the world.但它在其他地方相对温和 After the discovery of the bacterium that causes the disease,在人们发现导致这种疾病的细菌 and the realization that rats and fleas并在 19 世纪后期认识到 were the primary carriers in the late 19th century老鼠和跳蚤是主要携带者 and especially after the discovery of antibiotics,尤其是发现抗生素之后 the deadly grip that the plague had over the human species黑死病对人类致命的控制 began to finally fade away.终于开始消退 But the bubonic plague does still exist today.但是如今 黑死病仍然存在 Between 2010 and 2015,2010 年至 2015 年间 there were still 3248 recorded cases of the plague across the world.全球仍有 3248 例的黑死病记录 And on average,平均来说 nine people still managed to get infected by it在美国每年仍有 9 人 per year in the United States.感染该病毒 After thousands of years of chaos and earth-shattering pandemics though,然而经过数千年的混乱和震惊世界的流行病后 humanity has finally learned人类终于学会了 how to properly fight back against the bubonic plague.如何正确地反击黑死病 If you want to learn more about how diseases like this如果你想了解更多类似疾病 work on a biological level是如何在生物层面上发生的 or if you are curious for more information或者想知道更多 on the ongoing and evolving coronavirus pandemic,关于正在流行并不断进化的新冠疫情的信息 CuriosityStream has multiple fascinating short documentariesCuriosityStream有很多很好的短纪录片 like this one, this one, or this one.像这些 They will tell you about how the coronavirus began in Wuhan,它们能让你了解到新冠病毒是如何在武汉开始流行 how it spread to the rest of the world,如何传播到世界各地的 and how scientists across the planet are racing to discover a vaccine.以及全球科学家们是如何竞相研发疫苗的 There is plenty in each of them that will explain很多视频都能解释 how the world got to the point in the coronavirus pandemic世界是如何在新冠病毒大流行中走到这一步的 and these are just a few of the thousands of top-quality这些只是您可以在 CuriosityStream 上观看的 non-fiction shows and documentaries that you can watch on CuriosityStream.数千部高质量的非小说类节目和纪录片中的一小部分 Of course, the library that you get through a CuriosityStream subscription当然 如果现在订阅 CuriosityStream 频道可以获得更多资源 is now much larger thanks to their bundle deal with NEBULA.因为NEBULA是我们的合作商 The streaming video platform created by myself流媒体视频平台是由我 and loads of other educational creators.和许多其他教育创作者创建的 We made NEBULA to be the home我们把 NEBULA 建设成 of our bigger and more ambitious projects,我们更大规模且雄心勃勃的项目所在地 like my car review show Grand Test Auto比如我和来自 Second Thought 节目的 JT 创办的汽车评论节目 Grand Test Auto with JT from Second Thought where we drive and tell you我们会亲自驾驶汽车并告诉你 what we think about some pretty cool cars.我们如何看待某些非常酷的汽车 So to make sure you get to see that因此 为了确保您能够看到 along with all the other great original content由 Wendover 制作或 REAL ENGINEERING being produced by creators等创作者制作的 like Wendover productions or REAL ENGINEERING.所有其他精彩原创内容 Sign up for the CuriosityStream nebula bundle deal您可以在CuriosityStream.com/reallifelore注册 at CuriosityStream.com/reallifelore.CuriosityStream和nebula的联合账号 It is super simple.超级简单 Any subscription there comes with NEBULA included任何订阅都包含 NEBULA and at only 20 dollars for an entire year.全年只需 20 美元 This is the best deal that exists in the streaming world.这在流媒体中是很划算的 And as always, thank you for watching.感谢您的收看
  • 2022-06-27微观世界的复杂关系This episode is sponsored by Fabulous,本视频由美妙激励赞助 an app that helps you start building your ideal daily routine.这是一款可以帮助你建立理想日常的程序 The first 100 people who click on the link in the description最先点击简介中链接的100个人 will get 25% off a Fabulous subscription.将获得七五折的会员优惠 The world is simply too vast for any organism to find its way alone.世界真是太广阔了 让任何生物都没法自寻出路 There are too many turns, too many challenges…这儿有太多的变化和挑战 Inevitably, we all reach points in our lives where we just need a little bit of help.生活中 我们都难免会有需要帮助的时候 And the microcosmos is no exception.微观世界中也不例外 The world’s earliest relationship builders were microbes,微生物是世界上最早的关系缔造者 who—through some combination of chance and biology它们通过某种偶然性和和生理习性的结合 —found ways to use each other.找到相互利用的方法 The word for this, of course, is symbiosis,当然 有个词可以概括这个现象:共生 and it is not restricted to microbes.共生并不局限在微生物之间 You can watch many a nature documentary and find many examples许多自然纪录片中都能找到 of birds or fishes or large mammals that form symbiotic relationships.鸟类 鱼类或大型哺乳动物形成共生关系的例子 Perhaps one feeds on the pests living on another,也许一种生物以寄生在另一种生物身上的害虫为食 and the other provides shelter.而后者则为前者提供庇护 But there are many symbiotic relationships that we can see under the microscope as well.不过 显微镜下也可以观察到许多共生关系 One of the most famous examples of symbiosis is that of Paramecium bursaria.最著名的共生例子之一 是绿草履虫 The Paramecium bursaria looks like an ellipse with hairs poking out of it,它看起来像个长满了毛的椭圆 which means that for the most part,这意味着 大体上 it looks just like any other paramecium.它和其它草履虫看起来没什么两样 But there’s one big distinction: the Paramecium bursaria is green.但是绿草履虫有一个显著特点:它是绿色的 And it’s green, thanks to a whole host of algae called Chlorella这是它内部大量名为小球藻的藻类的功劳 Because, well, generations ago, many generations ago, a Paramecium ate some algae.因为好几世代以前 草履虫吃了一些藻类 But instead of digesting the algae, the Paramecium just didn’t.但是它没有消化 And instead, it started to consume the products of the Chlorella’s synthesis相反 它开始以小球藻的合成产物为食 and then it passed that algae on to the next generation.然后把小球藻传给了下一代 And in return, the Chlorella gets to use the paramecium—作为交换 小球藻开始利用它以前的捕食者 its former predator—as a form of protection and transportation.绿草履虫 来保护和运输自己 But scientists have separated the bursaria from it’s algal symbionts但草履虫和其藻类共生体后被科学家分离后 and it turns out, both of them can survive on their own.都仍然能独立生存 Because each of the members of the relationship benefits, 因为在这段关系中 双方都从中受益了 it’s called mutualism, 所以这被称为互利共生 but because it is optional it’s called facultative.但由于可以选择是否共生 我们又称之是“兼性”的 So the paramecium bursaria and its chlorella are an example of facultative mutualism.绿草履虫和小球藻就是兼性共生的例子 So, this all seems pretty simple and straightforward.这看起来非常简单明了 Symbiosis is a biological exchange of goods and/or services,共生是一种物质和/或需求的生物交换 an uncomplicated means of partnering up to help survive.一种并不复杂的结伴生存手段 But relationships are always easier in theory.但理论上的关系总是更简单些 In practice, they can be much more complicated and difficult to understand.实际中的关系 则更为复杂和难以理解 And for us, as outsiders,对于我们局外人来说 it takes considerable work to decipher just what kind of relationship光是搞明白微生物间建立的是何种关系 microbes are forming with each other.就需要大量的工作 James, our master of microscopes,我们的显微镜大师James found this ciliate in some mud.在某种泥里发现了纤毛虫 And if you’re wondering what those fuzzy rod shapes are inside of it,你可能会好奇里面这些毛茸茸的杆状物是什么 those are prokaryotes stuffing up the ciliate.其实这些是原核生物 填满了整个纤毛虫 But besides knowing that those are prokaryotes in there,但除了知道它们是原核生物以外 we can’t really tell much about what they’re doing我们无法真正了解它们在做什么 or what their relationship is with their ciliate host.或者它们和宿主纤毛虫之间有什么关系 Do those prokaryotes help the ciliate survive这些原核生物对于纤毛虫在低氧的 in the low-oxygen environment of mud?泥土环境中生存有没有帮助呢? Are they why we can’t see是它们导致纤毛虫身上 any food vacuoles in the ciliate?看不到任何食物液泡吗? Are they even helping each other at all or are they parasitizing each other?它们到底是在互相帮助 还是在互相寄生? Trying to decipher all of that just by looking at it仅仅通过观察来设法解读这一切 would be like trying to describe the complex dynamics of a family就像仅仅通过观察一个家庭的肖像 just by looking at their portrait.来设法描述其复杂的动态 So to dive deeper into what’s going on,为了深度剖析内部的活动 James has isolated and frozen some of these cells in tiny tubes,James将其中一些细胞分离并冷冻在小管中储存起来 storing them for a future day when he’ll be able to study them more closely.这样 他有朝一日能更仔细进行研究 Now, one of the disorienting aspects of symbiosis at the microbial level微生物水平共生关系的疑点之一是 is that eukaryotic organisms are full of parts真核微生物中充满了 that look a bit like other organisms.长得有点像其它生物的部分 And that is not a coincidence.这并不是巧合 In some cases,在某些情况下 things like chloroplasts and mitochondria are the product of endosymbiosis,叶绿体 线粒体之类是内共生的产物 过程中 a prokaryote that got consumed so completely by its symbiotic relationship一个原核细胞被共生关系完全吞噬进了 inside another organism that it has become an organelle.另一个生物 从而成了一个细胞器 The process of endosymbiosis is complete当内共生体失去大部分基因 when the endosymbiont has lost most of its genes or given them over to its host.或将其交给宿主时 内共生的过程就完成了 And that endosymbiotic history而内共生的过程 complicates our human desire to distinguish between an organelle and an organism.让人类区分细胞器和生物体的愿望变得复杂起来 But fortunately, we do have molecular tools 但幸好 我们的确拥有一些分子工具 that allow us to investigate further.来做进一步的研究 This diatom, Epithemia gibba,这种名为丝叶窗纹藻的硅藻 has had at least two distinct things noted about it:至少有两个值得注意的特点: one is its unusual capacity一个是它有不同寻常的能力 to convert extremely stable but biologically useless diatomic nitrogen将非常稳定但生物学上无用的氮气 into actually useful nitrogen compounds, we call this “nitrogen fixing”.转化为真正有用的含氮化合物 我们称之为“固氮” And the other thing that people have noted about it另一个值得注意的特点是 is the round bits that appear like beady bubbles inside of it.它里面有一些圆形的东西 看起来像亮晶晶的气泡 When scientists looked closer,科学家们仔细观察 they found that the round bodies had a double membrane around them,发现这些圆形物体由双层膜包被 suggesting that they might be another organism living inside the diatom.这表明它们可能是生活在硅藻内部的另一种生物 So they spun the diatoms and treated them with chemicals因此 科学家旋转硅藻 又对它们进行化学处理 to extract these mystery parts来提取这些神秘的部分 and studied the genes and signed them研究它们的基因并标记 ultimately finding that the diatom was occupied by cyanobacteria.最终发现 硅藻被蓝藻占据了 These cyanobacteria, it turns out, are responsible for the diatom’s ability to fix nitrogen.这些蓝藻使硅藻具有了固氮能力 It doesn’t appear to perform photosynthesis in the diatom,蓝藻似乎不在硅藻中进行光合作用 its main function is to fix nitrogen.它的主要功能是固氮 But to enter into that relationship with its host,但要与宿主建立好关系 the cyanobacteria had to change its own nitrogen-fixation schedule蓝藻必须改变自己的固氮计划 to match the diatom’s daily photosynthetic activities.来适应硅藻日常的光合活动 The extent of the cyanobacteria’s adaptation to its host蓝藻在宿主中很适应 and the fact that it is passed on from generation to generation of diatom硅藻也将蓝藻代代相传 suggests that while those cyanobacteria might still be their own selves,这说明 尽管这些蓝藻可能没有发生本质上的改变 they may be on their way to becoming an organelle,但或许 它们正在逐渐变成细胞器 fully endosymbiosed into a piece of Epithelia gibba.完全内共生为丝叶窗纹藻的一部分 And other mysteries remain, 而有些事最初一目了然 even when they seem initially clear-cut.后来却也变成其它谜团遗留了下来 This Loxodes rostrum is a rare find for us,对我们而言 这种扁形弯口吸虫是个稀有的发现 but it is also quite distinctive because it bears not one,它也很独特 因为它携带了并非一种 but two different types of algae in it.而是两种不同的藻类 And now, that might seem like yet another version of现在看起来 似乎像是之前所见的 the Paramecium bursaria and Chlorella relationship we saw earlier.绿草履虫与小球藻间关系的另一版本 We have a large ciliate occupied by algae,一个大纤毛虫 被藻类填满 combining their respective bodies and machinery 两种生物结合了它们各自的身体和机制 to supply different forms of nutrition to each other来互相供应不同的营养物 这些营养物 that neither would get on its own.都无法由藻类和大纤毛虫独自获得 There’s nothing weird about this, right?这没什么奇怪的 对吗? Nothing startling, nothing extraordinarily strange except本来是不怎么惊人 也没多古怪 that Loxodes rostrum are also full of pigments to avoid light because they don’t like light.可是扁形弯口吸虫内部还充满了避光的色素 because they don’t like light.因为它们不喜光 They practically melt when they’re exposed to light.暴露在光线下几乎会融化 And that’s a problem for algae但这对藻类来说是个问题 because light is kind of part of their thing, like,因为光线是藻类生命的一部分 it’s an important part of photosynthesis.换句话说 光是光合作用的重要组成部分 So how do they survive together?所以 它们是如何一起存活下来的呢? Why are they doing this?它们为什么要这么做? We don’t know.我们不得而知 There must have been some kind of compromise.这一定是达成了某种妥协 The nature of that compromise remains unknown to us.我们不知道这种妥协的本质 Maybe they’re just like that couple who seem deeply incompatible,也许它们就像一对看似极不和谐的夫妻 and yet somehow, they need each other and they make it work.但不知为何 它们需要彼此 并成功共生 At least, that’s how it looks from the outside.至少从外表上看是这样的 But in the future, generations of Loxodes from now,也许将来 扁形弯口吸虫会拥有 maybe this relationship will look different.与现在的共生不同的关系 And perhaps, like every other relationship, it will evolve,也许 像其它所有关系一样 共生将不断进化 helping both organisms confront new challenges帮助这对生物一起面对 这个世界 that the world will inevitably throw at them.给予它们的新挑战 这在所难免 Thank you for coming on this journey with us 感谢你一路陪伴我们 as we explore the unseen world that surrounds us.探索身边这个看不见的世界 And thank you to Fabulous for sponsoring this episode.感谢美妙激励赞助这一集 Every year most people set new-year’s resolutions大多数人会每年制定新年目标 but around 80% of those will get abandoned in just the first 2 months.但80%的人会在前两月放弃 The best way to succeed with your resolutions is to transform them into tiny habits达成目标最好的途径是将它们转化为小的习惯 and stick to them thanks to the Fabulous app.并通过美妙激励程序坚持它们 Developed by behavioral scientists at Duke University,美妙激励由杜克大学的行为科学家研发 Fabulous has guided journeys for common resolutions为常见的目标提供了指导性的方案 like exercising more, improving your sleep, and eating healthier.比如多锻炼 改善睡眠和健康饮食 It’s the #1 self care and habit forming app in the app store它是苹果商店里自我护理和习惯养成类程序第一名 with over 20 million users,拥有超过2千万用户 and it can help you whether you’re looking for ways to stay focused at work无论你是在寻找在工作中保持专注的方法 or you just need a reminder to take a break once in a while 还是你只是需要提醒自己 偶尔休息一下 to stretch and drink some water伸伸懒腰 喝喝水 它都能帮到你 There’s no shortcut to changing habits.改变习惯没有捷径 With your resolution this year, consider a proven,今年考虑一个成熟的 affordable, sustainable, long-term approach to changing your life,合理的 可持续的 长期的目标来改变你的生活 one that builds on your successes.建立在你成功的基础上 The app is 100% personalized to your goals这个应用程序根据你的目标进行个性化定制 and you can start building your ideal daily routine today!从今天开始建立你的理想日程吧 And the first 100 people who click on the link in the description前100位点击介绍中链接的人 will get 25% off a Fabulous subscription.能得到 七五折会员费优惠 You want to talk about a symbiotic relationship?你想谈论共生关系吗? How about the one that we have with the people whose names are on the screen right now.那和这些屏幕上这些人一起讨论怎么样? They are our Patreon patrons. They want there to be他们来自Patreon 想让网上 good, educational, interesting, chill, microscope content on the internet.有好的 有教育意义的 有趣的 轻松的显微镜下的内容 And we want to make it, but we need their support.我们也是 但需要他们的支持 And so, that relationship has come together, and what is the result?因此 共生关系也随之产生 结果怎样? This video and all of the other videos on this channel.频道里有了现在这个和其它所有的视频 If you want to be one of these people who make it possible for us to do this如果你想加入他们 一起帮助我们 and also get access to some pretty cool perks, you can go to patreon.com/journeytomicro.并得到一些很酷的额外奖励 请访问我们的网站 If you want to see more from our Master of Microscopes James Weiss,你想看到更多显微镜大师James Weiss的内容 check out Jam and Germs on Instagram.关注Instagram账号Jam and Germs And if you want to see more from us,如果你想看到更多我们的内容 I bet you, I bet you can find a subscribe button somewhere nearby.求求了 求求你找到边上的订阅按钮
  • 2022-06-27什么是信息理论?“玛丽 你人真好 希望我们可以常联系 我说过我会写信的 ” —你永远的朋友 乔纳森 于新斯科舍 1985 That was a message found in a half-broken bottle这是在克罗地亚海滩附近被冲上岸的 that washed up ashore near a Croatian beach.一个半碎的瓶子里发现的一条留言 It had spent nearly 23 years at sea 从书写到最终被发现 from the time of writing to the time it was finally found.这条留言在海里待了将近23年 Who Jonathon and Mary were, and what the message actually means,乔纳森和玛丽是谁?这条留言实际含义是什么? 我们也许永远不会知道 But this sort of a thing has captivated us all at one time or another.但这种事情曾一度吸引着我们所有人 The romantic element of a message in a bottle瓶子里留言的浪漫元素 that might only be read years, maybe decades later,如果最终能被大家所知的话 if at all is well known.可能需要数年或数十年的时间 however really, where the interest lies is in the desire of get a thought across.然而 漂流瓶的吸引力其实在于想要表达一种想法 A message. Maybe it’s to someone you love,一条信息!也许是给你爱的人 or maybe it’s to a complete stranger.也许是给完全陌生的人 And we don’t just care about what it is that we are saying,我们不仅在乎我们想说的内容 but also how it is received by the other person.而且关心别人是如何收到的 If Jonathan, say, really liked Mary,如果说乔纳森真的喜欢玛丽 not only would he want to make sure that his words reached her in this letter through time,他不仅要确保信里的话能随时间推移传到她那里 but he would also want to make sure that, when they do find their way to her,而且还要确保当这些话通过某种方式传到她那里时 that she gets the complete message.信息是完整的 While we no longer send hopeful messages in bottles these days,虽然如今我们不再用瓶子传递充满希望的信息 our concerns have not changed all that much; have they?但我们的担忧并没有改变多少 是不是? It’s still just as important to us对我们来说 让一个特别的人 that special someone gets our message quickly and efficiently.快速有效地收到我们的信息同样重要 Today, we might take the speed and accuracy of texting for granted,今天 我们可能认为短信的快速和准确是理所当然的 but the history of how we arrived here,但我们如何发展到现在的历史 like the man who made it all possible,就像让这一切成为可能的人一样 can sometime go unnoticed有时会被忽视 One Claude Shannon was thinking about the problem of information,克劳德·香农正在思考一个信息问题 at a time when the most consequential of professions was cryptography.当时最重要的行业是密码学 Shannon was one of the brightest in the field香农是该领域最聪明的人之一 and the importance of his work often meant他的工作的重要性在于 that he had a direct line to both the US and UK heads of state.他与美英两国元首有着直接的联系 Yet, these perks of the job were hardly of value to Shannon.然而这份工作的福利对香农来说几乎毫无价值 he was more intrested in theoretical aspects of reality他对现实的理论方面更感兴趣 The crux of it all, the fundamental principles that govern what we call “information.”最关键的是管理我们称之为“信息”的基本原则 these thoughts began a 10 year period这些想法使香农开始了长达10年的研究 in which Shannon worked, alone, on a unified theory of information在此期间独自致力于研究一个统一的信息理论 that would not only open the doors to a new field,这个理论不仅打开了一个新领域的大门 but also pose most of the important questions and answer them as well.而且也提出并回答了许多重要的问题 Shannon thought of information not as knowledge or intelligence,香农认为信息不像知识或智慧 but rather anything intentional that you can distinguish from noise.而是任何有意为之的 你可以从噪音中分辨出来的东西 How can you send a signal from one point to another你怎么能把一个信号从一个点发送到另一个点 and recover completely, or at least approximate并从介质的噪声中完全恢复 the signal from the noise of the medium?或至少近似地恢复信号? these were the questions Shannon really intrested in这些是香农真正感兴趣的问题 The key to answering those questions was to boil information down to one simple idea.回答这些问题的关键是将信息归结为一个简单的概念 Any information can be boiled down to a combination of “yes” or “no” questions.任何信息都可以归结为“是”或“否”问题的组合 True or false. On or off. Heads or tails. A 1 or a 0.真或假 打开或关闭 正面或反面 1或0 And thus, the binary digit, or bit was introduced to the world as the unit of information.因此 二进制数字或位作为信息单位被引入世界 To communicate a sentence for example,例如 为了传达一个句子 each character would have to be converted into multiple yes or no questions, or multiple bits.每个字符必须转换成多个是或否的问题 或多个位 But that wasn’t it.但不仅仅如此 Shannon also wanted to investigate the contents of the message.香农还想研究这条信息的内容 He, presumably informed by his cryptography work,他大概是受到了他的密码学工作的启发 realized that English like all languages has many patterns and tendencies意识到英语像所有的语言一样有许多模式和趋势 Thanks to these patterns,多亏了这些模式 we have learned to make sense of the language即使很多字符已经被删除 even when a lot of characters have been erased.我们也能学会理解这种语言 It’s the reason why texting feels so effortless这就是尽管简化的 不完整的单词和短语普遍存在 despite the prevalence of shortened, incomplete words and phrases发短信却让人感觉如此轻松的原因 what that also means is that language carries a lot of information that it really doesn’t need,这也意味着 语言携带了很多它并不需要的信息 especially when we are considering things like bandwidth and signal noise尤其是当我们考虑到带宽和信号噪声 and where we have to send a message as efficiently as possible.同时我们必须尽可能高效地发送信息的时候 But this idea extends to other forms of information as well.但这一想法也适用于其它形式的信息 The common image format “jpeg”常用的图像格式“ jpeg ” uses both contextual awareness and probabilities同时利用上下互文和概率 to store minimal information about the picture being stored.来存储有关被存储图像的最小信息 Of course, when you involve probability into anything,当然 当你把概率和任何事情联系在一起的时候 you forfeit the right to say anything with certainty, you are approximating.你就丧失了肯定地说任何事情的权利 你是在估算 Jpeg, too, loses some confidence in its dataJpeg也对其数据失去了一些把握 and some pixels may not be quite what they were in the actual image.一些像素可能与实际图像中的不完全一样 But, to the naked eye,但是用肉眼看 these compressed images often seem identical to the original.这些压缩图像往往看起来和原始图像一模一样 It’s why the jpeg format is able to achieve a 10:1这就是为什么jpeg格式能够达到10:1 (and sometimes even 20:1)compression ratio.(有时甚至是20:1)的压缩比 these compression foundamentals were crucial on the space race and voyage missions这些压缩原理在最终进入日常生活之前 before they finally made their way into our pockets.在太空竞赛和航空任务中至关重要 the video you are watching also goes to layers compression你正在看的这个视频在到达你的屏幕前 before it reaches the screen you are watching this video on.也经过了层层压缩 Tech Youtuber Marques Brownlee once experimented with this very phenomenon油管技术员马奎斯•布朗利曾经试验过这种现象 by uploading and then re-uploading the same video a 1,000 times通过重复上传相同的视频1000次 to see how the compression slowly rips the video apart.看看压缩是如何慢慢地撕裂视频的 Each time, the conversion leads to a slightly worse approximation每一次转换都会导致 of the original piece of information than the last time,对原始信息的近似略差于上次 and before you know it,在你意识到之前 you only left was blotches of colour that are hardly considered proper footage.只剩下了一些几乎不被认为是合适画面的色斑 But back to the fundamentals of information.但回到信息的基本原理 If I were to send you a message saying如果我给你发一条内容是 “上升的必然会下降” 的信息24次 how much of that message would truly be considered information?这条信息中有多少才是真正的信息? Instead of writing the same sentence 24 times,若不是把同一个句子写24遍 turning them all into bits,把它们都变成位 sending it over and then converting them all back to legible English sentences,发送过来 然后再把它们全部转换成清晰的英语句子 what would be more efficient is if I simply wrote the sentence once而是我只写一次句子 然后留下指令 and left a command for your device to copy the line 24 times when it reaches you让你的设备在句子到达时复制24次 那会更有效率吗 The 23 other iterations of the first sentence carry no information第一个句子的其他23次迭代没有包含任何信息 because it’s not something I don’t already know.因为这不是我不知道的 Think about it this way, if the weather in a region is always exactly the same,想想看 如果某个地区的天气总是一模一样 is there any reason for you to report on the weather?你有什么理由报道天气吗? It wouldn’t be informative at all.这没提供一点有用信息 From that perspective,从这个角度来看 the amount of information in a message is directly proportional to the amount of surprise in a message消息中的信息量与消息中的惊喜量成正比 meaning everything that you cannot reduce due to a pattern,意味着所有东西不能因为模式而减少 because whatever you can reduce, will be reduced.因为任何你能减少的东西 都会被减少 You are then only left with the disorganized,然后 只剩下需要作为整体存储的 out-of-pattern parts that will need to be stored as whole.无组织的 不符合模式的部分 of course, most messages don’t repeat the same line 24 times当然 大多数短信不会重复同一句话24次 This is just a simple idea to demonstrate the phenomenon.这只是一个简单的想法来论证这个现象 but really, English is said to be around 75% redundant但实际上 据说英语有75%的冗余 in that sense, it’s not wrong to say从这个意义上讲 如果说无趣的推文 that nosense tweets are more informative than Shakespeare比莎士比亚的作品更能提供信息并没有错 It is no wonder, then, that Shannon likes to equate information and entropy –难怪香农喜欢把信息和熵等同起来- something you and I usually call disorder.你我通常称之为无序 Shannon’s entropy is the absolute minimum amount of information香农熵是我们需要完全捕捉 that we need fully capture the contents of the message信息内容的绝对最小信息量 you would imagine that disorder typically completely opposite of being informative你可能认为这种紊乱与信息丰富完全相反 After all, in the physical sense,毕竟 在物理意义上 a disordered arrangement is the lowest energy, least useful state something can be in无序排列是能量最低的 最没用的状态 and we spend a lot of effort trying to prevent that from happening.我们做了很多努力来阻止这种情况发生 Yet, in the world of information, disorder is key.然而 在信息的世界里 无序是关键 However, the same trend does still apply.并且同样的趋势仍然存在 A tendency to move towards disorder is still a bad thing.走向混乱的趋势仍然是一件坏事 While we want surprising, disordered bits to be conveyed correctly,虽然我们希望出人意料的无序位能被正确传送 too much disorder will be indistinguishable from noise.但过多的无序将与噪音难以区分 Completely and utterly useless.完全没用 try to think of the information in a such fundamental level试着从这样一个基本的层面来思考信息 allowed Shannon to see it’s used in field one may not expect too让香农看到它被应用在了一个意想不到的领域 Thanks to an encouraging and challenging graduate advisor,多亏了一位鼓舞人心和富有挑战性的研究生导师 Shannon was forced to take a small detour into genetics during his time as a masters student.香农被迫在他攻读硕士期间绕了一小圈遗传学 He saw that genetics is just another way of transferring information biologically.他发现遗传学只是生物传递信息的另一种方式 Our bodies are anything but immune to the effects of aging.我们的身体绝不能抵抗衰老的影响 And at a deeper level,在更深层次上 this aging is really the loss of genetic information due to entropy.这种老化其实是由于熵造成的遗传信息的丢失 At the forefront of anti-aging research is Dr. David Sinclair.处于抗衰老研究前沿的是大卫·辛克莱博士 In his book Lifespan: Why we age and why we don’t have to,在他的《生命周期:为什么我们会老 为什么我们不必老》一书中 Dr. Sinclair refers to Shannon’s mathematical theory comunication 辛克莱博士将香农关于信息的数学理论 as a way to understand the age process.作为理解衰老过程的一种方式 Shannon, in his time,香农 在他的时代 was quite occupied with the problem of sending information over a noisy channel忙于在一个嘈杂的信道上发送信息 and ensuring the information get transferred properly并确保信息正确传输的问题 Dr. Sinclair says that the aging problem is similar辛克莱博士说 衰老问题是相似的 whereas in communication, say, between 2 computers而在通信方面 比如在两台计算机之间 you would have a source of information, a transmitter, and a receiver,你会有一个信息源 一个发射器和一个接收器 in the aging analogy,在衰老的类比中 the sources of genetic information would be the egg and the sperm,遗传信息的来源是卵子和精子 the transmitter would be the epigenome –传递者将是外基因组 and the receiver would be your body in the future.而接收者将是你未来的身体 We all start off with a clean copy of the source information.我们都从原始信息的一份完整副本开始 We grow into our teens我们成长到十几岁 and then some more in seemingly perfect condition然后在看似完美的状态下成长 until slowly but surely, every successive division,直到每一次连续的分裂因为熵 thanks to entropy, starts making mistakes.缓慢但肯定地开始出错 Keeping things ordered becomes harder and harder over time.随着时间的推移 保持事物的有序变得越来越难 Each successive copy of the source information每一个源信息的连续副本 is a slightly worse copy of the one you had before都是你之前所拥有的副本的一个略差的副本 – just like the Marques Brownlee video –就像马奎斯·布朗利的视频一样 till eventually you are left with a copy that barely resembles its old self –直到最终你只剩下一个几乎不像它原来的副本 wrought with illnesses, frail, and about to perish.充满了疾病 脆弱 即将死亡 To go back to the computer examples回到电脑上的例子 it turns out we have a solution to that problem.我们找到了这个问题的答案 your webpages don’t see the load any worse if you keep loading them如果你持续加载 你的网页不会变得更糟 是不是? Well, how do they compress things那么 他们如何在压缩的同时 and still manage to keep all the data then?还能保存所有数据呢? They use something called a TCP/IP protocol,他们使用一种叫做TCP/IP协议的东西 which essentially retains a perfect copy of the original website you meant to load它基本上保留了你想要加载的原始网站的完美副本 which can then be used to correct any errors during transmission.然后可以用来纠正传输过程中的任何错误 Wouldn’t it be great if we had a TCP/IP protocol如果我们的基因组和外基因组 for our genome and epigenome?有一个TCP/IP协议不是很好吗? It turns out we do.事实证明我们有 Known as four Yamanaka factors,被称为Yamanaka四因子 scientists Shinya Yamanaka and John Gurdon found 4 gene combinations科学家Shinya Yamanaka和John Gurdon发现了四种基因组合 that could turn old adult cells into potent stem cells.可以将老年细胞转化为有效的干细胞 they won a Nobel Prize medicine and physiology in 2012 for their discovery他们的发现获得了2012年诺贝尔生理学或医学奖 What this basically means for the anti-aging fight is这基本上意味着在抗衰老的斗争中 that we now have the perfect copy that we have all been looking for.我们现在有了 一直在寻找的完美副本 It’s now a matter of how we can access it现在的问题是我们如何获得它 and allow our body to rediscover their younger selves让我们的身体重新发现年轻时的自己 but for all the bad aspects disorder has gone so far但是尽管无序到目前为止有这么多不好的方面 let me be devil’s advocate for once.让我来做一次唱反调的人吧 Studies show that human to human,研究表明 人与人之间的 we are 99.9 percent identical in our genetic make up.基因构成有99.9%是相同的 What does the remaining 0.1% account for?剩下的0.1%是干什么用的? Let’s put it this way,让我们这么说吧 in the words of Ricardo Sabatini,用里卡多·萨巴蒂尼的话来说 “a printed version of your entire genetic code would occupy some你整个遗传密码的印刷版本将占据 262,000 pages, or 175 large books.大约262000页或175本大书 Of those pages, just about 500 would be unique to us.在这些页中 只有大约500页是我们独有的 Those 500 pages would be your essence, your likeness, your voice.这500页将是你的本质 你的肖像 你的声音 And according to Shannon’s theory,根据香农的理论 they are the disordered out-of-pattern, unique pieces它们是无序的 不规律的 独一无二的东西 you share with no one else.你不能和任何人分享 in another words,换句话说 disorder of those 500 pages that truly makes you ,you这无序的500页造就了真正的你 Try your best to preserve those pages尽你最大的努力保存你的独特 against the noisy tides of life.抗争生活的喧嚣 And if you can manage that,如果你能做到这一点 who knows, maybe someday someone might谁知道呢 也许有一天有人 find them in a broken bottle somewhere far, far away.会在很远地方的一个破瓶子里找到它们 Because remember, it’s the little things in life that truly count.因为要记住 生活中的小事才是最重要的 [广告]
  • 2022-06-27移动网络如何变成今天的模样This is electromagnetic radiation.这是电磁辐射 You can’t see it, but it’s there.你虽看不到它 但它就在那儿 In fact it’s everywhere.事实上 它无处不在 But here’s a more relatable form.不过以一个更贴近生活的方式来说 This is the color cyan.这是青这个颜色 But more accurately, this is waves但更确切地说 这其实是 of electromagnetic radiation oscillating at about以每秒约616856909465021次的频率 616,856,909,465,021 times per second.震荡的电磁辐射波 As they reach your eyes, light receptive cells当它到达我们的眼睛 光感受细胞 translate the radiation into electric signals which travel to your brain,会把辐射波转化为传入大脑的电信号 and are generally perceived as the color that we collectively refer to as cyan.大脑一般将这些电信号上认定为“青色”——这是共识 If we strip away our interpretation though,然而 若抛开我们的解释不谈 the radiation scaled up about 100,000 times, looks like this.那放大十万倍的辐射波 是长这个样子的 The color cyan is waves of energy roughly 486 nanometers wide,青色是约486纳米宽的辐射波 but what happens if that width tightens?那么如果这个波长变窄 会怎样呢? At 380 nanometers, a perception changes to this dark purple.在宽约380纳米时 大脑对其的感知会变为这种暗紫色 Meanwhile, if it expands to a roomy 780 nanometers,与此同时 若增加波长至780纳米 our brains interpret the radiation as the shade of dark red.我们的大脑会将其解读为 暗红这个色度 Essentially, as the wavelength changes,本质上来说 波长发生变化时 so too do the properties.波的属性也会变化 So what happens if we change the wavelength more dramatically,如果我们更夸张地改变一下波长 会怎样呢 like tightening it by 100 times?比如把它变窄100倍? Well, now the waves have much higher energy,那么 此时的波会具有更高更高的能量 they are much more powerful,变得强劲许多 so much so that they can actually pass through some less dense materials强到能真正穿透一些密度较低的材质 like fabric or human tissue.比如织物 或人体组织 But they aren’t quite strong enough to pass through denser materials但却没有强到足以穿透像金属或骨骼 like metal or bone.这些密度较高的材质 You can see where this is going.你应该已经知道了 We refer to these wavelength as X-RAYs,我们把这样波长的辐射波 称为X射线 and use their special properties to look inside bags at airport security,它们的特性使其能在机场安检处检查包内物品 and inside humans at the hospital.还有医院检查人体内脏时发挥作用 So what happens at the other end of spectrum?如果在光谱另一个极端 会发生什么呢? What if, instead the width of human DNA, the waves were the width of humans?假如波长不是像人类DNA这么宽 而是人类本身的宽度呢? Well, this is what we’d refer to, as an Ultra High Frequency Radio Wave.那它就是我们所说的 超高频无线电波 Its comparatively enormous wavelength allows it to travel over huge distances,相对较长的波长 使得它能够传播极远的距离 pass through obstructions and even bend around obstacles,穿越甚至绕过障碍物 all useful properties if you wanted to use electromagnetic radiation如果想将电磁辐射用于 比如通信 to, say, communicate.那么它所有的属性都有用处 Of course, in order to convey information using a radio wave,当然 为了用无线电波来传递信息 we’d need a way to manipulate the radio wave我们需要一种能够操纵 与所需信息 that corresponds to the desired information.相对应的无线电波的方法 For this, there are options.为此 有几个可选方案 To start with, there’s the strength of the wave.首先 从辐射波的强度开始 We know that a blue light, for example, can be weak or strong,我们知道 比如一个蓝色的灯 可明可暗 but no matter if it’s weak or strong, it’s still blue,但无论是明是暗 它始终是蓝色的 and the fact that it’s blue means that这个事实就意味着 it’s still fundamentally the same wavelengths of electromagnetic radiation.电磁辐射波的波长 在根本上始终是相同的 The same principle applies up to spectrum with radio waves.这个原理也适用于无线电波的波谱 They can be powerful, weak or anywhere in between它也是可强可弱 或介于强弱之间 and still be the same wavelength.并始终保持相同波长的 In this context, we call that strength, the Amplitude.这种情况下 我们把其强度称为 振幅 Therefore, we can transmit an audio signal for example,因此我们可以通过 以成比例的数值修改振幅 by modifying that amplitude by a proportional amount.来传输 例如一个音频信号 The receiver just needs to know how to interpret those amplitude modulations收音机只需要能够解读这些调幅 and translate them back to an audio signal.并将其转化回音频信号就可以了 In the case of an AM radio station就调幅无线电台来说 the radio receiver only focuses on the radiation无线电接收器只聚焦于比如说 with a wavelength for 1119 feet or 341 meters long for example,波长为1119英尺 或说是341米的辐射波 and it tracks the amplitude modulations然后它会追踪调幅 to output the audio signal that we end up hearing.来输出我们最终听到的音频信号 Amplitude modulation radio communication has a number of useful features.振幅调制无线电通信技术的确有很多优点 It’s exceptionally simple, and can work over huge distances,它极其简单可行 且能跨越极远的距离 but it does tend to be highly susceptible to outside interference.但又极易受外部因素干扰 That’s a big reason why AM radio tends to be lower quality,这就是为什么调幅收音机往往信号质量较差 and a big reason why it’s not as useful a technique也是它不适合作为更大组数据的传输技术 for transmitting bigger trunks of data.很重要的一个原因 Of course, the wavelength can also be manipulated.当然 波长也是可以操控的 That means that we can essentially do the same thing,这意味着 我们基本上可以利用同样的方法 but this time by ever so slightly modifying the distance between waves.但这次是通过稍稍修改波之间的距离来实现 In this context we’d refer to this as the frequency,在这个背景下 我们用频率来描述这个量 which is proportional to wavelength,它与波长成比例关系 but rather than being a physical measure, it’s a temporal one.但它是一个时间上 而不是实物计量上的单位 How many times the wave oscillates within a second?是指波在一秒内震荡的次数 So by slightly modulating frequency, we can transmit the same audio signal,所以说 我们可以通过略微调频来传输相同的音频信号 but since this method is less susceptible to interference,而由于这种方法不那么容易受干扰 we can generally get higher quality.我们通常能得到更高的信号质量 Now traditional radio works by encoding the audio signal itself现今 传统无线电设备是通过调幅或调频 into radio waves using amplitude or frequency modulation,将音频信号本身译成无线电波 来发挥作用的 but computers, phones, essentially everything digital nowadays, encodes its data但电脑 手机 基本上所有当今社会的数码产品 into binary code, sequences of ones and zeros.都会将数据转化为二进制代码 也就是1和0的序列 This only makes communication using electromagnetic radiation better.这样只会让利用电磁辐射的通信 变得更好 We can set it up so that我们可以 when the amplitude is high that corresponds to a one,将其设置成 当振幅高时对应1 while when it’s low it corresponds to a zero.而当振幅低时对应0 这样的机制 Or rather when frequency is high that’s a one,确切地说是 频率高时是1 and when low that’s a zero.低时是0 This is simple and already more efficient这样很简便 且已经比 than encoding the analog audio signal,编码模拟音频信号更高效了 but it could be even more efficient.但其实还有可能更加高效 That’s because there’s yet another wave property that we can manipulate.那是因为 还有另一种我们可操控的 波的属性 For these purposes, we can consider one full cycle of a wave,为此 我们可以想一下波的一个完整循环 going up, down and up again, one phase.上升 下降 再上升 为一个波段 But we can also consider this,也可以这样想 the wave going down, then up, then down again, one phase as well.波先下降 再上升 又下降 也是一个波段 Therefore, we could assign this upward phase to the binary digit one,因此可以将这个向上的波段确定为二进制数字1 and this one, the downward phase to the binary digit zero.而这个向下的波段 为二进制数字0 Then we can transmit data using a sequence of these different phases.然后我们就能利用 这些不同波段排成的序列 来传输数据了 The transmitter doesn’t need one phase to seamlessly go into the next,发射器不需要一个波段无缝衔接到下个波段 so it’s an even faster, even more efficient way所以说 这是一个更快 更高效的 of encoding binary sequences into electromagnetic radiation.将二进制序列编码为电磁辐射的方法 But here’s where things get really cool.真正精彩的部分要来了 There can be more than two phases.波段可以有不止两个 We could divide the cycle into one phase starting at the midpoint going upward,我们可以将此循环分成 一个从中间点向上的波段 one starting at the crest, one starting at the midpoint going downward,一个以顶峰为起点的 一个从中间点向下的 and one starting at the trough.和一个以波谷为起点的波段 So with four distinct phases,那么这四个不同的波段 one can correspond to the binary sequence zero one,一个可以对应为二进制序列01 one to one one, one to one zero and one to zero zero.一个为11 一个为10 还有一个为00 Therefore we can cram twice as much data into the same signal.因此 我们能将双倍之多的数据 塞进同一个信号中 But it doesn’t stop there.这还没完 We can even take this a step further and have eight distinct phases,我们还能更进一步 用到八个不同的波段 so that we can transmit every possible three-digit sequence of ones and zeros,这样 就能传输每个能得到的 0和1组成的三位数序列 thereby tripling efficiency.从而使效率提高三倍 Eight distinct phases is typically the practical limit for wireless data transmission.八个不同波段 通常就是无线数据传输实际可行的极限了 It becomes too tough to distinguish between phases with anymore,如果波段再多 区分它们就会变得过于困难 so the error rate is too high.导致错误率过高 However this is just manipulating one property of the wave,然而 这仅仅是操控波的其中一个属性 and there are, of course, two others.当然了 还有其他两个 This phase, initially upward from the midpoint,这个从中间点起向上的波段 could be broadcast at a high amplitude or a low amplitude.可以以一个或高 或低的振幅传播出去 So we can say that因此我们可以说 the low amplitude version of this correlates to the binary sequence of 0000,这个低振幅型 关联的是二进制序列0000 or the high amplitude version 0001.或这个高振幅型 关联的是0001 By adding two amplitude options to each of the eight phases,通过给这八个波段 各加上两个可选振幅型 we get 16 total transmission options,一共能得到十六个传输可选项 meaning we have enough to correlate to这意味着 有足够多的可选项 each of the 16 possible four-digit combinations of zeros and ones.与每一个可得的0和1组成的四位数序列相关联 If we have an accurate enough method of transmission,如果有一个足够精准的传输方法 we can further increase the number of phase 就可以进一步增加波段的数量 and amplitude combinations to a total of 64,和振幅的组合 至一共64个之多 each corresponding to a six-digit binary sequence.每个都对应一个六位二进制数 In fact, the newest WIFI standards have 1024 phase and amplitude combinations,事实上 最新的WIFI技术标准有1024种波段和振幅组合 while extremely accurate copper twisted cables can deal with 32,768 combinations,而极其精确的铜质双绞线 能够处理32768种组合 each corresponding to a 15-digit sequence.每一种组合都对应一个15位数的序列 Constrained by the accuracy of wireless communication,受制于无线通信的准确性 your cell phone meanwhile,我们的手机 uses as few as 16 combinations in the case of some 3G networks,在3G网络下 仅会用到少至16种组合 and as many as 1024 in the most advanced 5G networks.而最先进的5G网络下 则多至1024种 Fundamentally though, this is how your cell phone gets a lot of data本质上 这就是我们的手机从一小段 out of a little slice of the radio spectrum.无线电频谱中 获取大量数据的方法 Of course, transmitting data is only half the battle,当然了 传输数据只是成功的一半 something also needs to receive it.还得有东西接收数据 That something is, of course, a cell site.这个东西当然就是 基站 Now keep in mind that a cell phone is essentially just a fancy walkie-talkie.要记住 手机本质上只是一个高级对讲机 It uses the exact same process, just more advanced.它与对讲机的工作原理完全相同 只不过更先进些 In fact the earliest portable phones, car phones,事实上 最早的便携式电话——车载电话 which is one step removed from walkie-talkies.与对讲机的距离只有一步之遥 A telephone company would set up a radio transmitter in a city,电话公司会在城市里建一个无线电发射器 users would install a bulky system in their car,而用户需要在车内安装一套笨重的系统 the system would communicate with the transmitter just as a walkie-talkie would,系统就像对讲机一样 与发射器取得联络 and the tower would then plug the signal into the landline network.然后信号塔会把信号接入固网 Put it another way, it was just a citywide version of cordless landlines.换句话说 它其实就是个全市范围版的无线座机 The only difference from walkie-talkies与对讲机唯一的区别在于 was that these car phones would have a dedicated channel for outbound transmission,车载电话有专门的传出频道 and a dedicated channel for inbound transmission,和专门的传入频道 so that both sides could talk simultaneously,这样两边能同步对话 unlike with a walkie-talkie where one needs to wait and push to talk,不同于只使用单一频道的对讲机 需要 since only one channel is used.等待和按着说话 These car phones were fairly similar to today’s cell phones从用户体验角度来看 这种车载电话 from a user experience perspective,与当今的手机相当类似 but they were horribly inefficient.只不过其效率奇低无比 In their early days, there were only 32 available channels,在它问世的初期 只有32个可用频道 meaning only 32 people in the city could use their car phone simultaneously.这意味着 全市能同时使用车载电话的 只有32个人 In addition, if one left the service area of that one tower in their home city,此外 如果用户离开了自己故乡城市信号塔的服务区 their car phones wouldn’t work.那车载电话就不能用了 Of course, the solution was cells.当然 解决方案就在于基站 The idea was this,这个主意是这样的 a given area would be split up into a pattern of hexagons,将一个指定区域划分为一个个六边形 at the center of each of those hexagons was a cell site.在每个六边形的中心 是一个基站 These are generally thought of as cell towers,人们通常认为这些就是手机信号塔 but that’s a misnomer since cell sites can be located on buildings,其实这是错误的说法 因为基站可以设置在楼房上 inside church steeples, at the tops of mountains,教堂尖塔内 山顶上 或是 or really anywhere that’s elevated relative to the typical user.任何相对于普通用户来说较高的地方 Fundamentally, these cell sites just send本质上说 这些基站只是 and receive radio signals to and from cell phones,向手机发送 或从手机接收无线电信号 which is a fairly simple process.这是相当简单的流程 Then they need a way to plug into the wire communication network随后它们需要通过某种方法接入有线通信网络 to convey data over longer distances.以实现更远距离数据传输 Often this is accomplished through physical fiber optic cables,这一过程通常需要使用物理光缆来完成 but especially in more rural areas, that’s not always practical.但这并不总是可行的 尤其是在许多农村地区 If one put a cell site on the top of a mountain for example,比如要在山顶上建一个基站 it would likely have to operate completely offer grid它很有可能必须靠太阳能或发电机 power by solar or a generator.来为电网供能 And it also couldn’t physically plug into the wire communication network而且由于它是隔离的 无法在物理上 due to its isolation.接入有线通信网络 Therefore these more remote cell sites use microwave transmitters.因此 这些较偏远的基站 会使用微波发射器 Now tiny microwaves, thanks to their extremely rapid frequency,得益于极高的波频 现如今的微型微波 are incredibly efficient at moving huge amounts of data fast,在快速传送大量数据方面的效率十分惊人 the most advanced system have reached over 100 gigabits per second,最先进的系统已经能够达到100GB/s but they’re not very resilient.但灵活性不是很强 One needs a direct line of site要想准确地传输数据 between the transmitter and receiver to accurately transmit,发射器与接收器之间 必需有一条直通线路 which prevents microwaves used for portable cell phones.这就阻碍了微波在便携式手机上的应用 However, for fixed cell sites, this is possible.然而 这对于固定基站来说是可行的 So many are set up with microwave transmission systems许多基站设有微波传输系统 that relay signal to the closest site它会将信号转发至最近的 with a physical link to the wire communication network.且物理上连接着有线通信网络的站点 With both a wired and wireless option,有了有线和无线两种可选方案 cell sites can be located nearly anywhere,基站就可以设置在几乎任何地方了 which is important because their location absolutely matters.这很重要 因为它的所在位置关系重大 Centering their hexagon,每个基站的信号 the signal from each of these sites must reach far enough以六边形的中心为起点 必须能到达足够远的距离 that there is some overlap between the cells.让它们的覆盖范围 有一些重叠部分 That way, if a cell phone is being used on the move,这样一来 如果手机在移动中使用 the call can be seamlessly passed from one cell site to the next呼叫就可以在信号不衰减的状态下 with no drop off in signal,从一个基站无缝连接至下一个 and the network can be expanded far beyond the reach of one transmitter.且网络覆盖 会扩大到远超单个发射器的范围 However, the system starts to seem less ingenious once you do the math.然而我们一计算就会发现 它并没那么巧妙 Originally, only 832 different frequencies were allocated for use by cell phones.最初 仅有832个不同波频分配给手机使用 There are a lot of different uses for the radio spectrum,无线电频谱有许多不同用处 so regulatory bodies like the American FCC, British Ofcom or German Bundesnetzagentur,所以像美国联邦通信委员会 英国通信管理局 或德国联邦网络机构这样的管理单位 can only allocate so many frequencies for different industries.能分配给不同的行业的波频 只有那么多 And spectrum allocation is crucial而频谱的合理分配很关键 so that two users don’t try to use the same frequency,这样才不会让两个用户抢用同一个波频 or to render both of their uses useless.要不然两边都无法使用 So of those 832 frequencies,所以说这832个波频 42 were used by the cell network for its own back-end internal communication.其中42个 用于蜂窝网络自己后台的内部通信 That left 790, but a call required both an outbound还剩790个 而呼叫同时需要一个呼出波频 and an inbound frequency,和一个呼入波频 effectively meaning that there are only 395 call channels.实际上意味着 只有395个呼叫频道 However, in order to prevent interference,然而 为避免干扰 no two bordering cells could use the same frequency.两个毗邻的基站不能使用相同的波频 As each hexagon has six neighbors,由于每个六边形都毗邻其它六个 that meant each cell could only use one seventh of the available channels.每个基站能用的 仅为可用频道的1/7 So each cell had 56 channels,就是每个基站有56个频道 meaning 56 users within each cell could make a call at a given time.意味着在指定的时间 每个基站内有56位用户可以打电话 This initially works fine,最开始还好 but then cell phones got popular.但随后手机变得普遍 To keep up with demend,为了跟上人们的需求 cell carriers needed to find a way to do more with a single frequency.手机运营商需要找到一种能用单个波频做更多事的方法 When the second generation of mobile network came along,当第二代移动网络出现后 calls were no longer transmitted as analog audio waves,呼叫便不再以模拟音频波形式来传送了 rather, they started to use those digital signals encoded using phase and amplitude.反而开始采用利用波段和振幅译成的 数字信号 The thing was, this method was more efficient,事实是 这个方法更高效 meaning using a whole channel to transmit a single voice conversation was overkill,明明只需要用到一部分 却利用整个频道来传输 when only needed part of it.仅一个语音通话 太大材小用了 Of course, the difficulty was that voice conversations happen in a real time,当然 难点在于语音通话是实时的 it’s not like you could compress an entire two-minute call and send it at the end.它不像可以压缩 然后再发送的 一整段两分钟的语音 Therefore, cell companies divided a given channel into eight time slots.为此 手机运营商将指定频道划分为八个时段 These time slots would rotate one after another in a rapid succession,这些时段会一个接一个地 快速轮换 and a given phone would be told to use, say, the third time slot.然后规定某个指定的手机使用 比如说时段3 So, each time that time slot came up,那么每次轮到这个时段出现 it would fire off its ones and zeros quickly它就会迅速发射出多个10序列 and wait for it to come around again.然后等待再次轮到它出现 But because the data was compressed into an efficient digital signal,但由于数据被压缩成了高效的数字信号 the amount received during a time slot在一个时段内接收到的数据量 would be enough to decode into enough of the conversation,足以解码一段足够长的对话 to play until the next time slot came up.来持续播放至轮到该时段再次出现 This system meant that one channel这个方法意味着 could now be used by eight phones simultaneously.现在一个频道可同时为八部电话所用了 What was 56 channels, now became 448.本来的56个频道 现在变成了448个 But eventually, as phones became ever more commonplace,不过随着手机越来越普遍 the system of Time Division Multiple Access became这个时分多址的方法 once again, not good enough.又一次变得不够好用了 The next evolution was where things got complicated,接下来的这次演变复杂了起来 but also fascinating.但也颇引人入胜 It’s called Code Division Multiple Access.它叫作码分多址 It’s an ingenious way这是一种 where multiple phones can send and receive data能实现多部手机真正同时 on the same channel, truly simultaneously.发送和接收数据的巧妙方法 To explain the incredibly simple version,讲个高度简化的版本吧 let’s say a first user wants to transmit the binary sequence 11,我们假设第一位用户要传送的是二进制序列11 a second user 01, and a third 10.第二位用户是01 第三位是10 Now each of these users would be allocated what’s called a spreading code,现在每个用户 分别分配到一个传播代码 0101, 0011, and 0000 respectively.0101 0011 和0000 For the first user their first binary digit, 1,将第一位用户的第一个二进制数字 1 would be compared to each of the four digits of their spreading code.与其传播代码中的四个数字 一一对比 If the spread code digit and the binary digit is the same,如果其传播代码中的数字 与二进制数字相同 it would output a zero.则输出一个0 If it’s different, it would output a one.如果不相同 则输出一个1 So for user one, the output sequence would be 1010, 1010.因此 第一位用户输出的序列 将会是1010 1010 The process would repeat for user two, which output 0011, 1100.第二位用户也会重复这个流程 输出0011 1100 And user three, which output 1111, 0000.第三位输出1111 0000 Next, the sequences are translated接下来序列会被翻译 so that zeros become positive ones, and ones become negative ones.使0变成正1 而1变成负1 Then each digit of the three sequences of numbers are added together.然后将这三个数列中的每一个数字相加在一起 That outputs the composite sequence -1, 1, -3, -1, -1 ,1 ,1, 3.会输出复合序列 -1 1 -3 -1 -1 1 1 3 This composite sequence is what is then transmitted using a single channel.这个复合序列 就是接下来要通过单个频道传输的内容 Now the exact details of this process are not tremendously important,这个流程的具体细节不是十分重要 but what is, is what happens next.重要的是 接下来会怎样 What happens next, is that this process is reversed.接下来 这个流程会倒转过来 So, the receiver of that composite sequence该复合序列的接收器 会得知 would know each user’s unique spreading code.每位用户独一无二的传播代码 The spreading code is also translated该传播代码也会被翻译 so that zeros become positive ones and ones become negative ones.使0变为正1 而1变为负1 And then the receiver multiply the composite sequence with this translated spreading code.然后 接收器将复合序列与翻译得来的传播代码相乘 For user one,则第一位用户 that outputs -1, -1, -3, 1, -1, -1, 1, -3输出的是-1 -1 -3 1 -1 -1 1 -3 Now the first four digits of the sequence现在我们知道 序列的前四个数字 which we know correlate with the first digit of the data,是与数据的首个数字相关联的 are added together to get negative four,把它们相加 会得出负4 which is then divided by four to get negative one.用负4除以4 会得出负1 The process repeat for the second set of four to get negative one.第二组四个数字 通过相同流程得出负1 Now if we translate this back so that negative ones become ones,现在 如果把它们翻译回去 负1变成1 and positive ones become zeros,而正1变成0 then we get the data sequence, 11.那我们就会得到数据序列11 With just the composite sequence and unique spreading code,仅利用复合序列和独一无二的传播代码 this process figured out what user one’s unique data sequence was.这个流程就可以计算出用户独一无二的数据序列 If we repeat this entire decoding process with user two spreading code,如果对第二位用户的传播代码 重复整个解码流程 We’ll get 01, it’s data sequence.我们会得到数据序列01 And unsurprisingly, it also works for user three.毫无悬念 这也适用于第三位用户 So, with one composite signal and three unique spreading codes,因此 通过一个复合信号和三个独一无二的传播代码 we’re able to triple up the use of one channel.我们就可以让一个频道的功能翻上三倍 In practice, this process works in a much larger, much more complex scale,实际应用中 这个流程会在更大 更复杂的规模下运作 but it uses the same mathematical principles.但其数学原理是相同的 This fundamentally, is how Cell Service works.本质上说 这就是手机服务的工作原理 Making a two-wave radio work for one person is simple,让一个双波无线电为一个人服务很简单 making a two-wave radio work for everyone in the same area,让它同时为身在同一个区域的每一个人服务 at the same time, is difficult.并不简单 It’s all about packing as much data as possible into a single transmission,都是为了将尽可能多的数据 塞入单次传输 and then packing as many transmissions as possible into a single radio wave.再将尽可能多次传输 塞入单个辐射波 The aforementioned techniques to accomplish these two goals前文提到的那些 为了实现这两个目标的技术 are only the tip of the iceberg.只是冰山一角 Many of the most advanced networks has moved on to a system许多先进的网络 已经将目光转向 called Orthogonal Frequency Division Multiple Access,一个名为 正交频分多址的新系统了 to pack even more transmissions into a single wavelength for example.以求 在比如说单段波长内 塞入更多次传输 But they are indicative of the process that got us to today.而这些技术 却展现了我们时至今日的发展进程 When we move from 3G to 4G, and 4G to 5,从3G网络到4G 再从4G到5G what’s happening in the background is其背后是一群智者 incredibly smart people finding more and more ingenious methods of transmitting more data,不停探寻着 能利用同样的资源传输更多数据的 using the same resources, also that we, the end users巧妙绝伦的方法 此时的我们 这些终端用户 can browse Twitter, and watch Youtube, just ever, so slightly, faster.浏览Twitter 观看Youtube的速度才会快那么一点
  • 2022-06-2799%的海洋塑料垃圾“失踪”之谜Between Hawaii and California,在夏威夷与加利福尼亚州之间 in an area about twice the size of Texas–有一个面积约为德克萨斯州2倍的水域— is the Great Pacific Garbage Patch.它的名字叫大太平洋垃圾带 For decades, tons of our plastic debris has accumulated there数十年来 在旋转洋流的作用下 because of swirling ocean currents.成千上万吨的塑料残骸不断在那里堆积 It looks like a cloudy soup,垃圾带看上去就像浑浊的汤水一样 and that’s because the plastic objects are spaced far apart,是因为塑料物件之间的间隔较大 and they range in size from large debris to microscopic.塑料的尺寸从大型残骸到微塑料都有 There are at least 4 other garbage patches like this in the world, 全世界像这样的垃圾带至少还有4个 And after scientists discovered them,自上世纪90年代 starting in the 90s,科学家们发现垃圾带后 They thought that this might be where a lot of the plastic ended up,认为很多塑料最终都是来到该垃圾带 out there floating on the surface. 漂浮在那里的海面上 But recently, scientists brought large nets to the Great Pacific Garbage Patch,但最近 科学家们带着巨网来到了大太平垃圾带 and took a closer look at the objects they pulled out.并仔细观察了他们捞到的物件 They found water bottles发现了水壶 and hard hats以及安全帽 and bottle caps以及瓶盖 and toothbrushes以及牙刷 and toilet seats以及马桶盖 and laundry baskets还有洗衣篮 And using what they found, they were able to calculate利用捞到的物件 他们就能计算出 how much debris was in all of the garbage patches.整个大太平洋垃圾带一共有多少残骸 海面上漂浮着几十万吨的塑料 这可不是一个小数字 It is a big number.确实不是一个小数字 But a few hundred thousand metric tons of plastic但这几十万公吨的塑料 is only about 1% of the estimated 8 million tonnes of plastic在科学家们所认为每年排放入海 scientists believe is emitted into the ocean every year.约800吨的塑料中 仅占1%左右 So scientists have been left investigating a mystery:于是 科学家们只能不断调查一个谜团: Where does the rest of the ocean’s plastic go?海洋中其它的塑料都去哪了? This is clue number 1 in the case of the missing plastic:这是塑料消失案的一号线索 a sea floor sediment sample一个海底沉积物样品 It was taken from the bottom of the Santa Barbara Basin, off the coast of California.该样品取自加州沿岸的圣巴巴拉海盆底部 It represents a measure of time,样品代表着一段时间尺度 from 1870 at its deepest layer of sediment, up until 2009.从沉积物最深层的1870年到顶层的2009年 But this period, from 1945 to 2009,但从1945年到2009年的这段时间 is where the study authors were focused on.成了研究人员的关注焦点 It’s the era of plastic production.这段时间正是塑料量产的时代 In these layers, the scientists found plastic fibers and fragments在这些沉积层中 科学家们发现了 不超过1毫米的 that were 1 millimeter or smaller in size.塑料制的纤维和碎片 They found more and more plastic particles as the years went on,随着沉积层年份的递增 他们发现的塑料微粒越来越多 doubling every 15 years.且每15年翻一番 That rate is nearly identical to the rate of global plastic production.其增速与全球塑料产量的增速几乎一致 只要你看到的沉积层存在微塑料 就能确定其时间晚于20世纪50年代 这样的沉积层是我们这个时代的历史产物 This is Laurent Lebreton—这是Laurent Lebreton— he works at the Ocean Cleanup,他在海洋清理项目组工作 and led the study of the objects in the Great Pacific Garbage Patch.并且是大太平洋垃圾带物件研究的负责人 而且微塑料会永远待在沉积层里 我们清楚这一点 The sea sediment study looked at microplastics—海底沉积物的研究着眼于微塑料— particles smaller than 5 millimeters.即直径小于5毫米的塑料颗粒 These either come from synthetic clothing fibers,这些颗粒或来自合成服装的纤维 or they are the result of larger plastics breaking down.或由更大的塑料分解而来 We’ve found these tiny particles floating throughout the ocean,我们发现这些极小的颗粒漂浮在海洋各处 and even in the guts of the ocean’s tiniest creatures, like plankton.甚至存在于如浮游生物等海洋中最小生物的胃里 But the sediment study shows that some of our plastic is likely hiding,但沉积物研究显示 我们排放的塑料也有可能 buried in the sea floor, too.正被埋藏于海底 But here’s another clue:但这里有另一份线索 This is a plastic bag,这是一个塑料袋 captured 2,500 meters below the surface of the Arctic deep sea.被拍摄于北冰洋水下2,500米的深海 It’s one of over 2,100 photographs taken with this deep sea camera.这张照片是用这台深海相机拍摄的2,100多张之一 我们正在进行的工作中有一部分 就是观察气候变化在北极地区造成的影响 我们利用拖曳式摄像机勘测来观察 大型动物所受到的影响 如海星 蜗牛和海绵动物 而且我在勘测的时候 不断发现有塑料残骸正躺在海底 Melanie Bergmann’s research shows thatMelanie Bergmann的研究显示 large plastic objects don’t just float on the surface大型塑料物件 不仅仅漂在海上 or degrade into microplastic —或者被分解成微塑料— some of them sink without breaking down.有些塑料也会没分解就沉入了海底 One study found that about 50% of plastic in landfills一项研究发现 垃圾填埋场里约50%的塑料 is more dense than seawater,密度都大于海水 which means these objects could sink on their own.也就是说这些物件会自己下沉 But even those other 50 percent但事实上 连另外50%的塑料 may actually travel to the sea floor with time.都会随着时间沉入海底 漂浮在海面上的残骸会被各种有机体占领 如甲壳动物和贻贝 然后 塑料就会越来越重 在达到一定重量后开始下沉 Bergmann’s research is difficult to replicate throughout the ocean,由于勘测深海环境存在一定的挑战 because of the challenge of surveying the deep sea environments.Bergmann的研究很难复刻推广至整个海洋 But it suggests that some of that missing plastic但研究也表明 部分消失的塑料 might be sitting on the seafloor, intact.可能正完好无损的躺在海底 Another clue complicates the mystery, though:然而 另一个线索让谜团更加复杂了: this plastic crate, from Taiwan. 就是这个来自台湾的塑料箱 It’s one of the objects excavated during that harvest该塑料箱是那次在大太平洋垃圾带打捞时 in the Great Pacific Garbage Patch.挖到的物件之一 And what struck researchers was its production date: 震惊研究人员的是箱子的生产日期: 1971.1971年 When they looked at the production dates of other objects,研究人员观察其他物件的生产日期时 they saw a trend: a lot of it was old trash.发现了一个趋势:很多垃圾的年龄都不小了 This was a new lead:这给研究带来了新方向: because if the majority of plastic pollution degraded into microplastic因为如果大多数塑料垃圾都分解成了微塑料 or fell to the ocean floor,或沉到了海底 then what you’d see in garbage patches would be new plastic.那么你在垃圾带看到的塑料都应该是新的 这条线索改变了故事的走向 因为在海洋表面不断累积的塑料 实际上非常坚韧顽固 我们在亚热带海域发现的塑料 其实可能会在那漂浮几十年 甚至几百年 It turns out the new plastic is far closer than the open ocean事实证明 海岸上的塑料比公海里的塑料 or the bottom of the deep sea.或是深海海底的塑料要新很多 Lebreton’s research found that plastic objects on coastlinesLebreton的研究表明 海岸线上的塑料物件 have more recent production dates than plastic in the open ocean.生产日期比公海上的塑料更新 This clue led scientists to think a lot of debris这条线索让科学家们认为 actually stays close to shorelines around the world—其实很多残骸都在世界各地的海岸线附近— hidden in plain sight.藏匿于近在眼前的地方 Some of that will end up in the middle of the ocean and garbage patch,有些塑料最终会到海洋和垃圾带中去 but actually a lot of it stays fairly near shore但其实很多塑料都在离海岸相当近的地方 and hop from beach to beach to beach.并且会在不同海滩之间迅速位移 Erik Van Sebille is an oceanographer,Erik Van Sebille是一位海洋学家 and is building an ocean model他正致力于建造一个海洋模型 that predicts where our missing plastic ends up.该模型能够预测消失塑料的最终去向 The completed model will be finished in 2022,完整模型将于2022年完工 but in the meantime但在建造期间 he and his team publish initial results to a Twitter feed.他和他的团队会将初步结果发表到推特 We use simulations of the ocean currents.我们模拟了洋流 And then we put in virtual plastic.然后放进虚拟的塑料 We move that plastic with the ocean flow.这样我们就能让塑料随着洋流位移 At the same time the plastic and fragment can degrade, 同时 塑料和碎片都能分解 organisms start growing on it会有有机体开始在上面寄生 that weighs down the plastic给塑料不断增负 so that it slowly starts to sink into the deeper ocean.使其慢慢开始沉向海洋更深处 So in that way, we’re doing like this gigantic simulation我们就这样做着一个庞大的模拟分析 of all of the ocean, of all the plastic moving around.模拟对象包括了整个海洋和所有移动的塑料 Van Sebille thinks that a majority of plastic pollutionVan Sebille认为大多数塑料垃圾 is within 100 miles of shorelines,都在海岸线100英里范围内 continually getting washed back up on beaches不断的被冲回沙滩上 down coastlines, or up and down to the sea floor.堆在海岸下面 或在浮沉中来到海底 If the plastic continuously goes back and forth between the coastline and offshore,如果塑料一直来回地上岸又入海 that’s a lot of rubbing and fragmenting and scraping over the sand.就会大量地和沙砾摩擦刮擦 支离破碎 This commotion helps explain the presence塑料的暴力遭遇也更好地解释了 of microplastics in sediments and animal guts, too.沉积物和动物胃里微塑料的存在 Laurent’s organization is working on cleaning upLaurent带领的组织正致力于 the garbage patches in the middle of the ocean.清理海洋中的垃圾带 But that won’t do much for the other 99% of our plastic:但该项目对处理其它99%的塑料没什么作用: The microplastics becoming part of our food web and geologic record.其中的微塑料成为了我们食物链和地质记录的一部分 The larger debris sinking to the bottom of the ocean.尺寸较大的残骸沉向海底 And, more likely than not, the stuff getting washed up on beaches.而最有可能的是 塑料会被冲回海滩 Like this one, where I recently visited,比如这个我最近去过的海滩 where I found a mix of micro and larger plastics.我在这里发现了混杂的微塑料和大型塑料 But knowing where plastics end up但是 了解塑料的最终去向 can help us keep this plastic heap from growing.有助于我们阻碍塑料堆积的进一步发展 These photos were taken by volunteers这些照片是由志愿者拍摄的 at an annual, international coastal clean-up event,拍摄的活动是由海洋保护协会组织的 organized by the Ocean Conservancy,一项年度国际海岸大清理 where people volunteer to pick up plastic on the beaches near them.活动中人们自愿在附近的海滩捡拾塑料 The most common objects they find are food wrappers,人们拾到的物件中 最常见的有食品包装袋 烟蒂 塑料瓶盖 以及塑料杯盘 The easiest way to get plastic like this out of the ocean,清理海洋中这样的塑料最简单的办法 is to prevent it from entering in the first place,就是从源头防止塑料进入海洋 with better recycling programs办法是借助更好的回收计划 or producing and using less plastic altogether.或者从整体上减少塑料的产量与使用量 There are nearly 400,000 miles of coastline around the world,全球海岸线总长约40万英里 not all of it accessible for people.人类能到达的海岸是有限的 But knowing that most of our plastic pollution hangs out along shorelines但弄清楚了我们大部分的塑料垃圾在变成微塑料 before it becomes microplastics or floats out to the open sea,或是漂入公海之前 都待在海岸线附近这一事实 means beach clean-ups can go a long way意味着海滩清理活动 in preventing further damage.对于不造成更严重的恶果来说意义深远 So if you see plastic pollution on a beach—所以 如果在海滩上看到了塑料垃圾— all the more reason to pick it up.你就更有理由去把它捡起来了
  • 2021-09-07关于多相式睡眠 科学家到底知道什么?[ ♪ Intro ][片头音乐] Conventional wisdom says we’re supposed to get 8 hours of sleep a night.人们普遍认为 我们晚上的睡眠时间 应该达到8个小时 Fewer of us actually do,事实上能做到的人特别少 with the CDC reporting that a third of American adults snooze for less than 7.美国疾病控制与预防中心公布 三分之一的美国成年人 睡眠时间达不到7个小时 Now, the current consensus from sleep researchers is目前 睡眠研究者们的普遍共识是 that we need to sleep for long enough, continuously enough, and deeply enough我们需求足够长久 连续 深沉的睡眠 to receive the proper benefits of sleep.以便 能够获得相当的睡眠好处 And that’s a long list of benefits…睡眠好处可以列成一张长长的清单 like top cognitive performance, proper storage of memories,比如 很好的认知能力 正确的记忆储存 or avoiding health problems like high blood pressure and obesity.或者 防止诸如高血压 肥胖症之类的健康问题 We need sleep.我们需要睡眠 But some people try to break their sleep into chunks不过 有部分人设法将他们的睡眠分成几个时间段 instead of getting a single — or monophasic — stretch of Zs.而不是 保持单个的 或者说单相式的 睡眠时间段 Despite the trends,这种睡法尽管流行 there’s not much scientific evidence to suggest但是 并没太多科学证据表明 polyphasic sleep is better than monophasic.多相式睡眠比单相式睡眠更好 And some polyphasic sleep patterns are distinctly worse.而且 某些多相式的睡眠方式 明显更加糟糕 We don’t fully understand how sleep works.我们并没有完全弄懂 睡眠是如何运作的 The leading model for why and when you sleep关于你为什么和在什么时候睡觉 最重要的模型 is called the two-process model.被称为 双进程模型 It states that there are two, well, processes going on in your brain它表示 在你的大脑里 发生着这样两种进程 that dictate how sleepy you are at any given time.这两种进程决定着 你在任何特定的时间下 会感觉到有多困 One, called process C,其中一个 被称为C进程 is a product of your circadian rhythm,它是昼夜节律的产物 or the attunement of your brain to the cycle of day and night.或者说 是大脑对昼夜循环适应的产物 Your biological clock is run out of your brain’s anterior hypothalamus.你的生物钟受到下丘脑前部的控制 It ticks along in response to light,生物钟的运作受到阳光的影响 and makes you sleepier at night.它让你在晚上会觉得更困 The other, called process S,另外一个 被称为S进程 is homeostatic,它是内环境稳态的进程 which is to say换句话说 it reflects the need for your body to maintain a steady state in all things.它反映了 你身体需要让一切维持在一个稳定的状态中 We don’t know what exactly regulates process S,我们不知道 究竟是什么控制着S进程 but it may have to do with the buildup and clearing out of chemicals like adenosine in your brain.不过 它可能与大脑中化学物质 比如腺苷的累积和消耗有关系 The longer you’re awake,你醒着的时间越长 the more sleepy process S makes you.S进程就会让你觉得越困 And the longer you’re asleep,而你睡眠的时间越长 the more likely it is to wake you up.S进程就会更加有可能使你醒来 While scientists are still revising the two-process model,尽管 科学家们还在修正双进程模型 those basic parts do seem to explain不过 模型的基本框架 好像确能解释 why we sleep for a long time at night.为什么我们在晚上会睡上很长的时间 Process S and process C can change as you get older,随着你年龄的增长 S进程和C进程能够产生变化 and they operate independently from one another.并且 两种进程彼此独立运作 So it’s possible to separate your sleeping patterns因此 这有可能让你的睡眠模式 from the pattern of sunrise and sunset.不再遵循日出日落的模式 And scientists use this fact科学家们利用这个事实 to study sleep by placing subjects on an altered schedule.通过改变实验对象作息安排的方式来研究睡眠 In one oft-cited 1992 study published in the Journal of Sleep Research,在一项经常被引用的 1992年发表于《睡眠研究》期刊的研究中 7 participants were placed on a schedule7名实验参与者的作息计划 被安排为 with 10 hours of light and 14 hours of darkness.光照时间10个小时 无光照时间14个小时 Over the course of several weeks, they eventually took to他们经过几周的时间 最终养成这样的睡眠习惯 sleeping in two blocks during the dark period,他们在无光照的时候 分成两个时间段进行睡眠 with a few hours awake in between.而两段之间则会有几个小时的清醒时间 This, combined with historical knowledge, is sometimes used to suggest这个实验 结合历史知识 有时会被用来表明 that humans naturally adopted a biphasic sleeping pattern人类在拥有使自己熬夜的电灯之前的时代 in the days before we had electric lights to keep us up.会本能地采用两段式的睡眠方式 The idea of breaking up sleep into a polyphasic pattern, though,不过 采用多相式睡眠方式的想法 has been taken to some extremes.已经走向了某种极端 The scientist Buckminster Fuller somewhat infamously subscribed to the Dymaxion sleep schedule,科学家巴克敏斯特·富勒因为提出了 Dymaxion睡眠计划 而有些名声狼藉 which involves 4 30-minute naps evenly spaced throughout a 24-hour period.这种睡眠计划是 在24小时里间隔相同时间进行4次30分钟的睡眠 Some swear by similarly draconian napping schedules, like the Uberman,有一些人对类似的严酷睡眠计划推崇备至 比如Uberman式的睡眠计划 totaling only a couple hours of sleep per day.这种睡眠计划 每天总共也只有两个小时的睡眠时间 While others recommend longer “core” rests at night.然而 另一些人则建议晚上应该有更长的“核心”睡眠时间 Napping in the afternoon, or taking a siesta,中午打盹 或者说午睡 is technically a polyphasic sleep schedule,严格说来 就是多相式睡眠计划 and it’s followed in many parts of the world.世界很多地方都在采用 Breaking up your rests could work by affecting process S,多相式睡眠产生作用的方式 可能就是影响大脑的S进程 basically resetting the make-you-sleepier ticker more often.大致来讲就是 更加频繁地重新设置“让你更想睡觉”的时钟 However, polyphasic sleep isn’t well studied.不过 对多相式睡眠的研究并不完善 When it is, it’s in the context of shift work,多相式睡眠 总是出现在轮班制的工作环境中 like of people providing essential services in hospitals and fire stations.比如 在医院和消防站的轮班制工作中 A 2014 study in the journal Chronobiology International《国际时间生物学》2014年发表的一篇研究 argued that 12-hour shifts probably aren’t great for productivity.论证了 12小时轮班制很有可能对生产效率没有好处 After 12 hours of work,在工作12小时后 people may suffer from decreased alertness,人们警觉程度可能会降低 especially at night尤其在晚上 when their circadian rhythm is making them naturally sleepy. Instead,晚上昼夜节律会让他们自然而然地犯困 the researchers proposed shorter schedules,研究者们反而建议 更加短暂的作息安排 like 6 hours on and 6 hours off,比如 工作6小时 休息6小时 or 4 hours on and 8 hours off.或者 工作4小时 休息8小时 In the experiments they ran,在他们进行的实验里 29 participants were put on29名实验参与者的作息计划 被安排为 a 28-hour schedule with at least 9 hours of time in bed.总时长28小时 其中睡眠时间至少达到9小时 Half were on a conventional light-dark schedule其中一半参与者 采用传统昼夜式的作息安排 and half were broken up,而另一半 则采用多相式的作息安排 with periods of 4.6 hours of rest and 9.3 hours awake.睡眠时间4.6小时 清醒时间9.3小时 The two groups didn’t differ in their performance在警觉程度和反应时间的测验中 on a test that measured their alertness and reaction times这两组参与者的表现并没有区别 — even though participants on the split schedule尽管 采用多相式作息安排的参与者 sometimes reported feeling less alert.有时候会报告说感觉警觉程度在降低 And this led the authors to suggest这让实验制定者们认为 that shorter work shifts with shorter rest periods工作轮班时间短些 同时休息时间短些 could help shift workers.这对轮班制的工人 是有帮助的 However, it’s important to note the不过 重点要指出的是 participants still got in这些实验参与者的睡眠时间 a solid one third of their “ day ” as rest.还是整整占到了他们“一天”时间的三分之一 Less than that and you enter the realm of sleep deprivation,你睡眠时间少于三分之一 就会进入睡眠缺乏状态 which comes with a list of symptoms同时会伴随有很多症状 like anxiety, irritability, poor reaction times,比如 焦虑 易怒 迟钝 and longer-term health risks like high blood pressure and diabetes.以及 诸如高血压 糖尿病之类的健康危险 Some early sleep research failed to某些早期的睡眠实验表明 show any ill effects实验参与者每天睡眠时间只有4或5个小时 when participants slept for only 4 or 5 hours a day.而并没有产生任何负面的影响 But now, researchers think those experiments were poorly controlled.不过现在 研究者们认为 这些实验缺乏有效的控制 And more recent studies show最近更多的研究表明 drop-offs in cognitive function when less than 7 hours are spent in bed.睡眠时间没有达到7个小时 认知功能就会降低 Even worse, you may not know how exhausted you are.更糟糕的是 你可能并不知道 你到底有多疲倦 Some studies, including one from the journal Sleep in 2003,一些研究 其中包括2003年《睡眠》期刊上的一项研究 have found a disconnect between self-reported sleepiness and objective sleepiness利用脑电图通过对脑电波活动的检测 as measured by electrical activity in the brain, with EEG.已经发现了 主观上的困意和客观上的困意 是彼此分开的 Sleep-deprived people tended to think they睡眠缺乏者往往认为 were way better off than their scores on cognitive tests actually indicated.比起认知测试中真正得到分数 自己的认知状态要好上很多 And while it might be okay to break up your sleep a little,尽管 睡眠时间稍微分隔一下 是没问题的 researchers have also studied sleep fragmentation不过 研究者们还是对碎片化睡眠开展了研究 — when you wake up too many times during your rest period.碎片化睡眠 指的是 睡觉时醒来次数过多的睡眠 For instance, many researchers think比如 很多研究者认为 that uninterrupted sleep is necessary to store memories properly.对正确的记忆存储而言 不间断的睡眠是必须的 A study published in 2012 in the journal PLoS One found一项在2012年发表于《PLoS One》期刊上的研究 that subjects whose sleep was interrupted during a monophasic rest pattern发现了 在采用多相式睡眠方式期间 间断睡眠的实验对象 had an impaired ability to form memories.记忆形成功能方面 会受到损伤 So while we don’t understand everything yet,那么 尽管我们还没有弄清楚所有的事情 it’s clear that we need sleep to be our best selves.但我们清楚的是 我们需要睡眠来成就最好的自我 And our brains definitely need more than two hours.而且 我们大脑肯定需要超过2个小时的睡眠时间 You can try to reprogram it if you want to,如果你想要 你可以尝试对大脑重新编程 but it’s at your own risk.不过 风险自负 Thanks for watching this episode of SciShow!谢谢收看本期《心理科学秀》 If you want to learn more如果你想了解更多 about some groundbreaking discoveries biologists have made about sleep,生物学家们对于睡眠领域的突破性发现 check out our list show all about it!请收看我们所有关于睡眠的节目吧 And if you just want to keep getting smarter with us,你要是想要和我们一起不断变得更加聪明 you can go to youtube.com/scishow请登录网址youtube.com/scishow and subscribe.订阅我们吧 [ ♪ Outro ][片尾音乐]
  • 2021-09-07机器人外科医生和其他4项如科幻小说的医学进展《科学秀》 Modern medicine is pretty incredible.现代医学成就让人叹为观止 But even in a world where open-heart surgery但即便在心脏直视手术 and brain-scanning headsets sound almost mundane,和耳机式脑扫描仪都很寻常的当今世界 some medical advances do truly一些医学进展确实 seem like science fiction.看起来像科幻小说一样 So here are five recent developments下面五项近期医学进展 that sound like they’re straight out of the future,尽管听起来像是来自未来 but are already around today.但如今已成为现实 Robots and surgeons go way back—机器人外科医生很早就有 in fact, robots have been in operating rooms实际上 机器人在手术室中应用 since the late 1980s,开始于20世纪80年代末 helping out with all types of routine procedures.用于辅助完成各种常规的工作 But in February 2020,但是 2020年2月 surgeons in the Netherlands kicked things up a notch.荷兰外科医生提高了机器人应用水平 They used a very precise robotic arm他们使用了非常精确的 with teeny tiny tools on the end末端带有微型工具的机械臂 to operate on blood vessels just a few times the size of a human hair.能在只有几倍头发直径的血管内进行操作 It was the first human trial这是人类进行的首次 of robot-assisted supermicrosurgery,机器人辅助超显微外科手术试验 which is surgery on vessels smaller than eight-tenths of a millimeter.手术是在小于8/10毫米的血管内进行的 Surgeries at these scales are really tricky for humans,这样微观级别的手术对人类是很困难的 because our hands do shake— maybe just a little bit,因为人手难免会抖动 哪怕幅度很小 but at these scales, every millimeter counts.但在这个级别一毫米都很重要 So only highly-trained surgeons所以只有训练有素的外科医生 are capable of doing these procedures.才能够完成这类手术 One of these very precise surgeries,此类精确手术的其中一种 called a lymphatico-venous anastomosis, or an LVA,被称为淋巴静脉吻合术 或LVA is a treatment for breast cancer patients它是针对淋巴液不能正常回流的 whose lymph isn’t draining properly.乳腺癌患者的一种治疗方法 Lymph is a fluid that transports white blood cells淋巴液是一种在体内输送白细胞 and other nutrients around the body—和其它营养物质的液体 and when it doesn’t drain properly,如果不能正常回流 it can cause swelling and pain.会引起肿胀和疼痛 But with surgery, tiny lymph vessels can be connected to blood vessels但通过手术将小淋巴管与血管相连 to give the lymph another way out.给了淋巴液另一个引流途径 This surgery is at the very limit of human capabilities,这项手术几乎超出了人类能力的极限 but the team of surgeons and roboticists in the Netherland但是荷兰的外科医生和机器人团队 thought they might just be able to认为他们也许能够 make the procedure easier and safer.让手术变得更容易 更安全 They devised a robot called MUSA,他们设计了一款名叫MUSA的机器人 which mimics a surgeon.完全模仿外科医生 It has two arms that go over the patient,它用两条机械臂给病人实施精细操作 with tiny surgical tools on the ends instead of hands.其末端的微型手术工具可代替人的双手 To manipulate the robot,为了操控机器人 a surgeon looks at the patient through a microscope外科医生通过显微镜观察病人身体 and moves a set of controllers并操作一组控制器 as if they were operating directly on a person.就像直接在病人身上操作一样 But it’s the robot’s tiny tools that are actually performing the surgery.但实际上是机器人的微形工具在完成手术 The robot mimics the surgeon’s movements exactly,机器人可以精确地模拟外科医生的动作 except it filters out tremors.只是滤除了抖动 It also scales those movements down,机器人也缩小了动作幅度 since the surgeon is looking at the patient through a microscope因为医生在用显微镜观察患者 and making bigger motions.手上动作幅度较大 Out of 20 surgeries, MUSA assisted in eight,MUSA协助了20例手术中的8例 and all of them were a success.都获得了成功 Unlike a human, the robot didn’t twitch or get tired,与人类不同 机器人不会痉挛或疲劳 and it could hold an awkward position forever if it had to.需要的话它可以永远保持一个别扭的姿势 This success is really exciting,这次成功很令人鼓舞 because a robot like MUSA could因为MUSA这类机器人 make this type of complex surgery possible for more surgeons—能够帮更多外科医生进行此类的复杂手术 which means more people could get the treatment they need.这意味着更多人可以获得所需的手术治疗 The reason a lot of people who are paralyzed can’t move their limbs许多瘫痪的人无法移动四肢是因为 is because the nerves that should be taking signals本应在大脑与其他身体部位间 from the brain to the rest of the body传递信号的神经组织 aren’t working the way they should.没有正常工作 And for many people with this kind of nerve damage,对许多此类神经损伤患者 the condition is permanent.这种病是终身的 But in a case study published in 2019 in the journal但在2019年《柳叶刀神经病学》 期刊的 The Lancet Neurology,一项病例研究中 a team of researchers in France found a creative way一个法国研究团队发现了一个开创性方法 for a man who was paralyzed below the neck可以让一个脖子以下瘫痪的男子 to control his limbs again.再次控制自己的四肢 Their idea was to bypass the nerves completely—他们的方案是完全绕开神经 by recording messages straight from the brain直接记录来自大脑的消息指令 and sending them to a machine that could carry out its orders.并将其发送给能执行指令的机器 The solution combined incredible advances方案结合了两项不可思议的先进科技 in both brain scanning and robotics.脑扫描和机器人技术 First, the team inserted two small implants into the patient’s brain首先研究团队将两个小装置植入患者大脑 to measure activity in the areas that control movement.以检测运动控制区域的大脑活动 The implants were hooked up wirelessly to a computer system,植入装置以无线方式连接到计算机系统 which decoded the brain signals对大脑信号进行解码 and translated them into instructions将其转换为控制虚拟化身 for a virtual avatar or a full-body exosuit.或全身机械装置的指令 But it was not as straightforward as it sounds.但这并不像听起来那样简单 See, scientists know which regions科学家知道大脑的哪些区域 of the brain broadly control movement,在大体控制人的运动 but for this contraption to work,但是要使这些装置起作用 the system needed to match up an exact pattern of active brain cells该系统需要将确切的脑细胞活跃模式 with a specific movement.与特定的运动相匹配 And that’s not exactly easy.而这并不容易 Like, what does [this] look like on a brain scan, compared to, like, [this]?“这样”和“这样”时 脑扫描有什么区别呢? The team started by having the patient think about a specific action —该团队先让患者思考一个特定的动作 like rotating his wrist or moving a wheelchair forward.比如旋转手腕或向前移动轮椅 The computer—which was hooked up wirelessly to his brain—无线连接到患者大脑的计算机 would record the signals that thought created.会记录思考时产生的大脑信号 Then, over the course of two years,这样 在两年的时间里 the computer created a model of the patient’s brain—计算机创建了一个患者大脑活动的模型 basically like a dictionary that matched brain patterns to movements.就像是将脑的活动模式与特定运动相匹配的字典 In a way, he was both training the computer一方面 患者要训练计算机 to understand his brain signals,理解他的大脑信号 and training himself to think in a structured and focused way同时训练自己有条理地 专注地思考 that a computer would understand.以便于计算机理解 And in the end, the patient was able to use the system最终 患者能够使用该系统 to do all sorts of things!执行各种操作 He drove a wheelchair and made virtual hands do things可以开动轮椅 让虚拟手臂做诸如 like turn over or touch a target.翻转或触摸目标的动作 He also gained the ability to start and stop an exoskeleton.患者还有了启动和停止机械外骨骼的能力 It was attached to a harness mounted on the ceiling,外骨骼与装在天花板上的系带相连 so while he wasn’t completely independent,因此虽然患者不是完全独立 he could essentially walk.但他确实可以走路 Now, this wasn’t the first time scientists created an interface这不是科学家们第一次创建 between a brain and a computer,大脑和计算机的接口 but the small surgery it required但这次所需的小手术 was much less invasive than other methods.比其它方法带来的伤害小得多 And while it’s still a long ways from widespread use,尽管该系统离广泛使用还很遥远 it’s a big step toward developing a way for paralyzed people但在为瘫痪人士开发出仅用意念 to control robotic limbs with nothing but their thoughts.就能控制义肢方法的道路上前进了一大步 In March 2020, doctors in Oregon announced that2020年3月 俄勒冈州的医生宣布 they had used the DNA-editing tool CRISPR-Cas9他们首次在活人身上使用了 in a living person for the first time.基因编辑工具CRISPR-Cas9 Their goal was to treat a rare genetic condition that causes blindness他们的目标是通过修复出错的基因编码 by just fixing the faulty code in the DNA.来治疗导致失明的罕见遗传病 Which is actually possible这其实是可能的 because Cas9 is an enzyme that can cut apart molecules,因为Cas9是一种能切开分子链的酶 and it allows researchers to snip a strand of DNA它使研究人员可以在精确的位置 at a precise location把DNA链剪断 and replace faulty code with new instructions.并用新基因编码替换错误的编码 This technology itself isn’t that new.这项技术本身并不是特别新奇 Scientists have been using it to edit genes2013年以来 科学家们一直在用它 in bacteria, fruit flies, plants, and other organisms since 2013.编辑细菌 果蝇 植物和其它生物的基因 And in a different study, also published in February of 2020,2020年2月发表的另一项研究显示 doctors actually edited the white blood cells of three people with cancer—医生实际上编辑了三名癌症患者的白细胞 but they did the editing outside the patients’ bodies.但他们是在患者体外进行编辑的 That same month, though,不过 就在同月 the team in Oregon took gene-editing a step further俄勒冈州团队将基因编辑向前推进了一步 when they announced that they had used it directly in the human body他们宣布已开始使用该技术直接在人体内 to edit the genes of living cells—编辑活细胞的基因 although when we filmed this video,不过我们录制此视频时 they didn’t yet have their results.他们的结果还没有出来 This clinical trial involved a patient该临床试验涉及的患者 with a rare inherited eye disease患有一种罕见的遗传性眼病 called Leber congenital amaurosis,叫作利伯氏先天性黑矇 which affects the cells of the retina and causes blindness.能影响视网膜细胞 并可导致失明 And this disease can be caused by这种疾病可能是由于 a mistake in a gene called CEP290 –CEP290基因的突变而引起的 that’s what researchers wanted to fix.这就是研究人员想要修复的问题 In the trial, doctors used a needle to inject a few drops在试验中 医生用针头将几滴 of a solution containing the CRISPR-Cas9 system含有CRISPR-Cas9系统的溶液 into the space just behind the retina.注入视网膜后方的空间 The idea was that CRISPR-Cas9 would find the cells of the retina医生设想CRISPR-Cas9会找到视网膜细胞 and snip away the mutation,并剪除突变基因 leaving behind a functional gene.留下一个功能正常的基因 If it works, it should be a permanent cure.如果起作用的话 应该能永久性治愈该病 And the retina is a good place to test out gene editing in humans,视网膜是测试人体内基因编辑的好地方 because it’s isolated from the rest of the body—因为它独立于人体其他部位 so changes made on one eye won’t affect any other part of the body.一只眼的变化不会影响身体的其它部位 After all, there are a lot of valid reasons毕竟 在人体内做基因编辑 to be concerned about doing gene-editing in humans—我们是有足够理由感到忧虑的 but this is a pretty safe place to start.但这是一个非常安全的起点 And if the procedure does cure the patient’s blindness,如果该手术确实治愈了患者的失明症 it’s not just good news for people with this rare disease;这不仅对患有该罕见病的人是个好消息 it could open up the possibility for other gene therapy treatments as well.它也许会为其它基因疗法开辟可能性 These days, there’s not much you can do现如今 要是你刮破了膝盖 if you scrape up a knee or get any injury that breaks the skin.或受到任何皮肤损伤 你能做的很有限 It’s just got to heal, and it takes as long as it takes.只能等它愈合 而且需要的时间很长 But in 2018, 但在2018年 researchers at the University of Wisconsin-Madison威斯康星大学麦迪逊分校的研究人员称 reported that they had built a device他们制作的装置 that healed injuries in rats four times能使老鼠伤口的愈合速度 faster than they heal on their own.比其自然愈合速度提高四倍 The device itself is really simple:装置本身非常简单 It’s basically a little electric bracelet其实就是一个小的电子手镯 that delivers gentle electric pulses to the site of an injury.可以向受伤部位传递柔和的电脉冲 Now electricity naturally plays a role in helping wounds heal.电流天然地就有帮助伤口愈合的作用 Scientists have known since the 1800s that从19世纪初期 科学家就己经知道 anytime you get an injury,如果你受伤了 your body naturally creates an electric field around it.你的身体会自然地在伤口周围产生电场 And in more recent studies, researchers have even watched在最近的研究中 研究人员甚至观察到 cells move around and restructure themselves细胞在电场作用下 in response to an electric field.开始移动并自行重组 You know. As they do.研究人员做这些试验时 They still don’t know exactly他们仍不清楚 how the cells are responding to that electricity,细胞对于电流的反应的确切原理 but electricity seems to promote the growth of new cells,但是电流似乎可以促进新细胞的生长 which is what it takes to close a wound.而这恰好是伤口愈合所需要的 So this device was designed to speed up healing因此 该装置的作用是为创伤区域 by providing additional electricity to the injured region.提供额外的电流以加快伤口愈合速度 And in rats, the results were kind of incredible.在老鼠身上试验的结果出人意料的好 An injury that normally took almost two weeks to heal通常几乎要两周才能愈合的伤口 closed up in three days.三天就愈合了 Eventually, researchers hope to最终 研究人员希望 test something like this on human skin.在人类皮肤上测试类似装置 And in the meantime, they’ve found evidence that同时他们发现 有证据表明 this technology may even have an extra perk—该技术甚至可能还有一个意外功效 it might reverse baldness.可能会逆转脱发进程 In a separate experiment,在另一个实验中 they applied a patch with the same technology他们把运用相同技术的贴片 to mice with a genetic condition用到患遗传病的老鼠身上 keeping them from producing certain chemicals that make hair grow.该病会阻止老鼠产生某些促进毛发生长的化学物质 So the mice are naturally hairless,所以这些老鼠天然是没有毛发的 but after just nine days,然而仅仅过了9天 they’d grown hair under the electric patch.老鼠电极贴片下的皮肤长出了毛发 Researchers believe the patch works研究人员认为 这些贴片 by stimulating the cells in the area通过刺激该区域的细胞起作用 so they release those chemicals that tell hair to grow.释放出了促进毛发生长的化学物质 Now, you may have noticed that你可能已经注意到 your head is not mouse skin.你的头皮不同于老鼠皮肤 But if tests in humans go well,但如果人体试验顺利的话 products with this technology could eventually hit the market,采用该技术的产品有望最终推向市场 but in the meantime— in case you need me to say it—但同时 我要提醒大家的是 don’t try this at home.请不要在家中尝试 Everywhere around the world,在世界各地 there are more people who need organs than there are donors.需要器官的人都比捐献者要多 Like, right now, there are over 100,000 people in the U.S. waiting for kidneys.比如目前 美国有超过10万人在等待肾源 And even in a record-setting year like 2019,即使在2019年这一创纪录的年份 fewer than a quarter of those people will get them.也只有不到1/4的人能得到所需肾脏 So lives depend on finding more kidneys.所以 生命的延续有赖于寻找更多的肾脏 And in 2015, doctors in the U.K. found a new way2015年 英国医生发现了一个 to put kidneys from deceased donors back in business,能将死者肾脏恢复正常功能的新方法 using a technique called ex-vivo normothermic perfusion.使用了一种称为体外常温灌注的技术 This technique uses a jolt of nutrients该技术使用了一些营养素 to repair kidneys from deceased donors来修复已故器官捐献者的肾脏 and make them usable again—which is not easy.并使它们可以再次使用 这并不容易 Because, as soon as a person dies, their organs start to deteriorate.因为人一旦死亡 器官状况就开始恶化 Doctors can slow that deterioration by chilling an organ,医生可以通过冷却器官减缓恶化进程 but even then, kidneys have to be transplanted within a day or two,即便如此 肾脏必须在一两天内移植 or they’re often too far gone.否则通常就不能用了 This new procedure helps by putting new life into kidneys这项新技术通过给肾脏注入新的生机 that have passed the usual point of no return.来挽救通常已经过了使用时限的肾脏 First, the kidney gets removed from the deceased donor先像平常一样 将肾脏从捐献者体内取出 and kept cold, just like usual.并保持冷藏状态 Then it has to travel—然后是运送过程 sometimes down the hall, other times to a different city.或运过大厅 或运送到另一个城市 Once it gets where it’s going,一旦到达目的地 it goes into a special machine that’s kind of like a spa肾脏会被放入一台类似水疗的特殊机器 But for kidneys,it pumps warm blood and nutrients它专为肾脏设计 通过器官向肾脏输送 through the organ until it’s working at peak efficiency.温热的血液和营养 直至其达到最强功能 Then it’s good to go back to work in the world of the living.然后欣然回到一个有活力的身体继续工作 What’s cool about this procedure is该技术的优点在于 it doesn’t just wake the kidney back up—它不仅可以唤醒肾脏 it also gives the surgeons a chance to make sure还能让外科医生有机会确认 the kidney works on a machine, before it goes into a human.肾脏在进入人体之前 能先在机器上运作 Kidneys that were borderline become healthy enough处于生死边缘的肾脏在水疗之旅后 to use after this little trip to the kidney spa.就能重获健康 再次应用 And, so far, the early results are promising.目前为止 早期结果比较乐观 Initial studies show that the revived kidneys are at least初始研究表明 机器恢复的肾脏至少 as safe as kidneys typically used for transplants.与通常用于移植的肾脏一样安全 Other trials are still in progress to make sure it’s completely safe,其他试验仍在进行 以确保其绝对安全 but if things go well, this could save a lot of lives.但如果一切顺利 它能挽救很多人的生命 For now, many of these advances are proofs of concept目前 这些进展还处于概念验证阶段 and still far from being your everyday reality,距离我们的日常生活还很遥远 but they show how quickly science fiction can become science但这展示了科幻小说正快速变为科学现实 and help us to live longer, healthier lives.并让我们更加长寿和健康 Thanks for watching this episode of SciShow!感谢收看本期《科学秀》 And a special thanks to our patrons on Patreon特别感谢我们在Patreon上的支持者 who make it possible for us to share让我们得以跟大家分享 all this amazing science with you.这些惊人的科学资讯 If you’d like to join our amazing community of patrons,如果您想加入我们优秀的赞助人团 you can find out more at patreon.com/SciShow.可在patreon.com/SciShow找到更多信息
  • 2021-09-07伪装:动物捉迷藏嘘!我们正在玩捉迷藏!Shh! We’re playing hide and seek! 但是,我似乎不能找到Squeaks.你能吗?But, I can’t seem to find Squeaks. Can you? 轻音乐播放着[Soft music playing] 啊哈!找到了!Hah! Found yah! 咯咯的笑![Giggles] 在这里,我们很擅长捉迷藏。Here at the fort, we’re pretty good at hide and seek. 你知道为什么吗?You know why? 因为我们从大自然中学到了许多很棒的技巧。Because we’ve learned a lot of great tricks from nature! 许多动物都有它们自己的捉迷藏方式。There are lots of kinds of animals that have their own kind of hide and seek — 一些动物藏起来,因此它们能悄悄靠近它们的猎物Some animals hide so they can sneak up on their prey– 其他动物藏起来,因此它们不会成为晚餐other animals hide so they don’t become dinner! 不管怎样,这些动物不会藏在窗帘后面或者桌子下面Either way, these animals don’t hide behind curtains or under tables 像是当我们捉迷藏时做的那样like we do when we want to play hide and seek — 它们躲藏在大自然当中they hide in plain sight! 听起来很不错!That sounds amazing! 它们能这样做多亏了伪装的本事And, they can do it thanks to camouflage. 一个叫做Rianne的SciShow Kids电视观众想要知道One SciShow Kids viewer named Rianne wants to know: 伪装是什么,是怎么工作的?What is camouflage and how does it work? 问题非常好!Great question! 伪装是一些动物迷惑或者躲避其他动物的一种方式Camouflage is a way for animals to confuse, or hide from, other animals. 自从许多不同的动物都在躲藏或者寻觅Since lots of different animals are all either hiding, or seeking, 在大自然中就有了许多不同种类的伪装there are lots of different kinds of camouflage in nature. 对于动物伪装的一个简单方法就是把它们自己混入到背景当中One easy way for an animal to camouflage itself is to just blend in with the background. 比方说你在树林中安静的散步时Let’s say you take a quiet walk in the woods — 你希望看到什么动物?what kind of animals would you expect to see? 好吧,在我住的地方,我可能会看到一些松鼠Well, where I live, I might see some squirrels, 或者是一头鹿,也可能是一只可爱的小田鼠or, a deer, or maybe a cute little field mouse. 你觉得这些哺乳动物们拥有的共同点是什么?And you know what these mammals all have in common? 它们都有棕色或者灰色的渐变色They’re all shades of brown or gray — 它们搭配着它们居住地方的树皮的颜色和森林底色they match the color of tree bark and the forest floor where they live. 这使它们更难被发现This makes them harder to spot. 许多动物混入到它们所处的环境中Lots of animals blend in with their environment, 但是并非所有动物都依赖它们的颜色去伪装but not all of them rely on their color to do it — 一些动物也从它们的皮毛图案中得到帮助some animals get help from the patterns on their skin and fur. 老虎的黑色大条纹使它们在高高的草丛中更难被发现Tigers have big black stripes, which makes them harder to find in tall grass. 在小鹿身上斑点是浅黄褐色的And the spots on baby deer, called fawns, 看起来的图案像是阳光闪烁着look like patterns that sunlight makes as it shines 照射穿过树木和草丛down through trees and grass, 因此当它们想要美美的休息一会时会蜷缩在植被中so when they curl up among some plants for a nice nap, 很好的混入其中they blend right in. 现在,生活在水里的动物们Now, animals that live in the water have a 有一个不同的环境需要去混入different environment that they have to blend into. 许多海洋动物,像是海豚,鲨鱼,和鲸鱼Many ocean animals, like dolphins, sharks, and whales, 通常都是浅灰色,或者蓝色来搭配水的颜色are often light gray, or blue-ish, to match the color of the water. 但是它们也有另外一个技巧,它们胃的颜色要But they have another trick, too, they’re lighter on 比他们背的颜色更浅their stomachs than they are on their back. 看这只鲨鱼,它被叫做灰色暗礁鲨Look at this shark, it’s called a gray reef shark. 如果你在这只鲨鱼上面游泳时,往下看If you were swimming above the shark, looking down, 它的蓝灰色的背会和它身下海水的颜色混为一体its blue-and-gray back would blend in with the waters of the ocean below it. 但是如果你在鲨鱼下面游泳往上看时But if you were swimming under the shark and looking up, 当阳光穿过它时,它的白色的胃会和上面的水的颜色相匹配its white belly would match the lighter water above, as the sun shines through it. 你可能会说这个鲨鱼从头到尾被覆盖了You might say this shark is covered from top to bottom! 一些动物既不依靠颜色也不依靠它们自身的图案And some animals don’t just take on the color or pattern 它们利用它们的形状来伪装of their surroundings — they camouflage themselves using their shape! 看看这个家伙。你能看到吗?Take a look at this guy. Can you see it? 这被叫做行走的树叶!毫无疑问!It’s called the walking leaf! And no wonder! 这个行走的树叶不仅有绿叶的颜色和形状The walking leaf not only has the color and shape of a 他甚至标记他的身体看起来像是被啃咬了一样green leaf, it even has markings on its body that make it look like it’s been nibbled on. 现在,试着找到这条多叶的海龙Now, try to spot this leafy sea dragon. 全身被小鱼鳍覆盖,Covered in small fins all over its body, the leafy sea 多叶海龙完美的融入到他们生活的海草当中。dragon blends perfectly in the seaweed where it lives. 这种多叶海龙甚至像是一片海草一样移动,The leafy sea dragon even moves like a piece of seaweed, 优雅的在水里翻筋头gracefully tumbling around in the water. 这是一种很有说服力的伪装That’s some convincing camouflage! 但是当然,许多动物和他们身处环境中的东西看起来并不完全一样But of course, a lot of animals don’t naturally look like things in their environment. 所以他们中找到一些方法去隐藏自己…像是玩装扮So some of them have found ways to hide themselves by … playing dress up. 装扮过的螃蟹沿着海底漫步,The dresser crab walks along the seafloor, looking for 寻找它们可以穿上的外壳little things that it can wear on its shell– 像是珊瑚,海葵或者海藻。like coral, sea anemones, or seaweed. When it’s all 当他掩盖或者静坐时,这个螃蟹几乎是看不见的!covered up and sitting still, the crab is nearly invisible! 然后还有这种叫做蒙面猎人的昆虫。Then there’s this insect called the masked hunter. 当它们年幼的时候,它们被细毛覆盖。When they’re young, masked hunters are covered in tiny hairs. 当他丢掉身体上面的灰尘时,他会黏在毛发上,When it throws dust on top of its body, it sticks to the hairs, 完全覆盖它。covering it completely. 它像是一个隐形的斗篷!It’s kind of like an invisibility cloak! 所以现在你明白了吧。So there you have it. 动物们利用各种技巧去隐藏它们自己,Animals use all kinds of tricks to keep them hidden, and 每种动物的方法都有稍微的不同。every animal has a slightly different way to do it, 取决于它们是什么,生活在哪里depending on what kind of animal it is, and where it lives. 谢谢和我们一起学习伪装Thanks for learning about camouflage with us! 你有什么想要了解更多的问题吗?Do you have a question about something that you’d like to learn more about? 从父母那里得到帮助。请在下面留下你的评论或者电子邮件kids@thescishow.comGet help from a parent, and leave a comment below or email us at kids@thescishow.com. 让我们下次再见And we’ll see you next time! 音乐播放中[Music playing]
  • 2021-09-07关于猫咪的冷知识What if I told you that there might be a sneaky predator如果我跟你说 在你家里可能有一个 with super powers in your house right now?潜在的 拥有超强能力的捕食者该怎么办呢? If you live with one of these, there is!如果你和其中的一只在一起生活 那就是真有 I’m talking about cats!其实我说的就是猫! And even if you do have a cat of your own,即使你有猫 I bet you don’t know some amazing things那我敢肯定你也不知道 about our little furry friends!我们毛绒绒的小伙伴的神奇事儿 For example!比如! Did you know that all pet cats are actually related to lions,你知道其实所有的宠物猫都和狮子 and other big cats, like tigers,以及其他像老虎 leopards, and jaguars? 豹子和美洲虎这样的大型猫科动物有关吗? Wait…this…is related to this? 等等……小猫咪……和大老虎有关系? Yes it is!是的! All cats, from the biggest lion to the tiniest of house cats,所有的猫科动物 大到狮子小到家猫 evolved from the same small, cat-like creature 都从一种小而像猫的生物进化而来 that lived millions of years ago 它们叫做原猫或“第一只猫” called proailurus or “first cat”.生活在几百万年以前 Then after a long time,在很长一段时间之后 there came to be two major types of cats.猫科动物进化出了两个种类 One kind became the bigger cats, like the lion and the tiger.一种变成了更大的猫科动物 像狮子和老虎 And the other kind became the smaller cats,而另一种变成了更小的猫科动物 which includes the ones we keep as pets today.包括我们现在养的宠物 So…if all big cats and all little cats descended所以…如果所有的大猫小猫 from this same animal from long, long ago都从同一种生物进化而来 that means they’re related那么即使它们之间有差别 even if it is only distantly.但还是有联系的 That’s one big furry family! 那可是一个毛绒绒的大家庭! Now another cool thing about cats?接下来另一件关于猫的很酷的事情 They have excellent hearing!它们的听力很棒 Lots of animals, including dogs, have better hearing than we do.包括狗在内的很多动物都比人的听力好 But cats can hear better than both human and dogs.但是猫的听力比人和狗的更好 Even if your cat just looks like it’s curled up and enjoying a relaxing nap,即使你觉得你的猫看起来喜欢蜷起来睡午觉 extremely aware of its surroundings.但它仍然对周围的一切了解得一清二楚 Their little ears are super-sensitive, 它们的小耳朵非常灵敏 and they’re always listening.并且一直保持听的状态 Your cat can can hear everything that’s going猫可以听到它周围的一切 on around it, from the sound of you从你在楼上任何位置的卧室里 listening to music in your bedroom all the way upstairs,听音乐的声音 to the sound of birds chirping到邻居院子外面 outside in your neighbor’s yard.小鸟叽叽喳喳的声音 In fact, cats can hear things up事实上 猫能听到的声音的距离 to four times further away than you or I can是我们的四倍远! And they can not only hear things而且它们不仅能听到远处的声音 from far away—they can figure out exactly where而且能精确的判断 those far-away sounds are coming from.这些声音从哪来 So if your cat’s snoozing in the basement,所以如果你的猫正在地下室打盹 and you open the kitchen cupboard where you那么当你打开存放它们 keep their favorate treats,最喜欢的零食的橱柜时 they’ll probably come running.它们就会马上跑过来 But if you open another cabinet in a different part但是如果你打开厨房里 of the kitchen, they’ll probably be另一个橱柜 able to tell the difference and just keep snoozing!它们可能会听出区别然后接着打盹 Thousands of years ago,几千年之前 cats needed this super sense of hearing to help them track down food猫需要有极好的听力来帮助他们寻找食物 and to escape predators in the wild. Today,并且在野外逃离捕食者 now that they live among humans 现在既然它们已经和人类生活 who help provide for them人类可以给它们食物 they don’t need it quite as much.它们就不太需要它了 But it’s always good to know但是 当橱门打开时能听到 when that treat cupboard opens!这总是很好的 And lastly, our third cool thing about cats: They rule! Well,最后一件酷事儿:它们的地位至高无上 sort of!在某种程度上是这样 Some ancient cultures—like people who lived一些古老文化—像几千年前 in Egypt thousands of years ago — 生活在埃及的人们—— treated cats like royalty,把猫当做 皇室成员对待 almost as if they were kings and queens!大部分猫像国王和王后一样 Early Egyptians were thought 据说早期的埃及人总是觉得 to have had problems with rats in their homes.自己家里有老鼠 In order to get rid of the rats,为了赶走这些老鼠 they brought in cats to hunt them.人们引进了猫来捕捉 And the people liked the cats so much,人们非常喜欢猫 they supposedly kept them 所以就收养了它们 and treated them extremely well.并对它们非常好 Ancient Egyptians even mummified the animals古埃及人甚至为了来世的旅行 for their journey to the afterlife,就像对待人类统治者一样 just like they did with their human rulers.把猫做成了木乃伊 So sorry, dogs.所以很抱歉 狗狗们 in ancient Egypt at least, 至少在古埃及 cats ran the show.猫更胜一筹 Now the next time you see a cat,下一次你看见猫的时候 you’ll know that you’re looking at 你就知道你在看 a super-cuddly animal with super-hearing一只超可爱并且听力超棒的动物 that was once treated like royalty 那是一只曾经地位至高无上 and is related to lions and tigers!并与狮子老虎同源的动物 And if you’d like us to sniff out所以如果你想了解 more information about cats or anything,更多关于猫的知识 just let us know!就来联系我们! Get help from a grown up让父母帮助你们 and leave a comment down below,在下方评论 or send us an email或者给我们发邮件 kids@thescishow.com.邮箱为kids@thescishow.com Thanks for joining us!感谢加入我们 We’ll see you next time, here at the fort!我们下次再会!
  • 2021-09-07木星,是敌是友?[INTRO ♪][前奏] Jupiter is more than twice as massive as all the other planets in our solar system combined,木星比太阳系中其他所有行星加起来的两倍还要大 and it has a history of throwing that weight around.而且它的质量一直都在向四周散失 In fact, it likely used its gravity to shape the way our solar system looks today.事实上 木星可能凭其质量塑造了太阳系今天的样子 And that’s generally a good thing for us!整体上来说 这对我们是好事 We have a nice stable orbit at a cozy distance from our star,地球与太阳距离适中 公转轨道平稳 and things are usually pretty calm in our planetary neighborhood.周边行星环境相当平静 So, here on Earth, we have a lot to thank Jupiter for…所以 我们地球有很多需要感谢木星的 but it isn’t always the nicest neighbor.但它并非一直是个好邻居 Now and then, it also sends some hazards our way.它也时不时的使地球处于危险中 That makes sharing a solar system with Jupiter … complicated.这使得与木星同处一个太阳系的感情变得复杂了 On a good day, Jupiter’s got our back.好的时候 木星在背后支持我们 When comets from the outermost reaches of the solar system head toward Earth,比如彗星从宇宙深处来到太阳系冲向地球时 Jupiter’s gravity often acts like a shield by chucking them straight into interstellar space.木星的引力像护盾一样 将它们直接抛到星际空间 And we’ve even seen Jupiter take some pretty big hits for us.我们见识过木星帮我们挡掉一些相当严重的撞击 In 1994, fragments of the comet Shoemaker-Levy 9 smashed into Jupiter.1994年 彗星Shoemaker-Levy 9的碎片撞击了木星 As the impact site rotated into the Earth’s view,当撞击点旋转到面向地球时 scientists could see dark scars on the surface of the planet科学家观测到了木星表面上的黑斑 and plumes of debris rising in its atmosphere.还有碎片尘埃漂浮在大气层中 If a comet like this had hit Earth,假如类似的彗星撞击地球 it would have kicked up an enormous cloud of dust that would have blotted out the Sun将会扬起巨大的尘埃云 遮蔽阳光 and caused mass extinctions on par with the ones that took out the dinosaurs.造成地球生物大灭绝 规模与恐龙灭绝那次不相上下 So not only does Jupiter routinely protect us from comets like Shoemaker-Levy 9,所以木星不仅日常保护地球不受类似Shoemaker-Levy 9彗星的撞击 but that dramatic collision gave astronomers a wake-up call它被撞击也给天文学家提了个醒 —if it happened to our neighbor, it could also happen to us.能发生在邻星上 那也能发生在地球上 Just four years later, in 1998,就在四年后的1998年 NASA got serious about tracking near-Earth objects, or NEOs,NASA开始重视追踪近地天体 简称NEOs that could have catastrophic effects if they hit our planet.指撞击后会导致地球灾难性后果的天体 And now NASA estimates that we’ve found almost all of the thousand or so NEOsNASA目前估算已找到近千个 big enough to cause apocalyptic worldwide destruction.几乎所有大到能导致地球末日的NEOs There are, of course, still plenty of smaller ones that could potentially do some serious damage,虽然仍有许多可能造成严重破坏的较小近地天体 but thanks to Jupiter’s wake-up call in the ’90s,但还是要感谢木星在90年代的提醒 we have a pretty good handle on the scariest threats.让我们对其中最具威胁的彗星做好了应对措施 So, Jupiter deflects some dangerous comets木星使一些彗星偏离方向 and reminds us to keep a lookout for incoming asteroids,并提醒我们注意将到来的小行星 but the biggest planet in the neighborhood doesn’t always play nice.但这个最大的行星邻居并不总是那么友好 For example, in 1770, the comet Lexell flew past it,比如1770年 彗星Lexell掠过木星时 and Jupiter’s huge gravity directed the comet right at Earth.其巨大引力使该彗星直冲地球 It came within 2.3 million kilometers of us!最近时离我们只有230万千米 That’s how far Earth travels in just 21 hours.相当于地球公转21小时的距离 So we dodged it by less than a day!所以我们躲开它时只剩不到一天 And research suggests that this type of event—而且研究表明 类似事件像 where Jupiter throws things into the inner solar system rather than sending them out木星吸引小行星到太阳系内部而不是将其抛向外太空 —might be happening more often than we thought.发生频率可能比我们想象的更多 Like, one simulation of 30,000 space objects比如一个包含3万个天体的模拟 showed that Jupiter might even be teaming up with Saturn显示木星甚至可能与土星协作 to send threatening space rocks our way.将颇具威胁的太空岩石抛向地球 In the model, each simulated object began in a non-threatening orbit somewhere in the outer solar system.模拟开始时 每个天体运行轨道在外太空某个地方 But by the end of the simulation, 8% of those objects were crossing paths with Earth.而到最后 有8%的轨道会与地球相交 And while Jupiter’s gravity was the real culprit slinging objects inward,虽然是木星将它们吸引到太阳系 堪称罪魁祸首 Saturn was guiding objects toward Jupiter.但是土星将它们引向木星 也“功”不可没 In the real world, a good deal of Jupiter’s ammo is likely made up of objects called Centaurs.现实中 木星的“弹药”可能大部分由半人马小行星构成 They’re named after the mythical creature that’s half-person, half-horse,它们的名字来源于半人半马的神话动物 and Centaurs are like hybrids between asteroids and comets:而它们也像是小行星和彗星的“混血” They can have the same make-up as asteroids,它们与小行星组成成分相同 but many of them have comet-like properties like tails of debris.同时很多还有彗星的特征 比如彗尾 For the most part, Centaurs stick to the outermost solar system.大多时候 半人马小行星呆在外太空 But if they get close enough to Jupiter,但一旦它们离木星足够近 the planet’s gravity can alter their path木星的引力就能改变它们的轨道 and throw them into the inner solar system,把它们吸引到太阳系 potentially on a collision course with Earth.并可能与地球发生激烈碰撞 Even when it’s not hurling Centaurs our way,就算木星没有把它们投向地球 Jupiter may make ordinary comets more of a threat than they already are.它也能使本具威胁的彗星变本加厉 Although it throws some of them out of the solar system altogether,尽管木星把一些彗星清出了太阳系 in other cases, a run-in with Jupiter can tighten a comet’s orbit.但其他时候 木星的干扰会缩短彗星的轨道 That means it’ll go around the Sun faster,意味着彗星将加速环绕太阳运行 giving it more chances to hit Earth.增加撞击地球的可能性 In fact, that’s exactly what happened with the famous Comet Hale-Bopp.事实上 这正是著名的海尔波普彗星发生的事情 It last swung by the Sun in 1997,它最近一次掠过近日点是在1997年 and that was the first time it was visible in 4,000 years.这是它4000年来第一次被观测到 But around the same time, an encounter with Jupiter cut its orbital period almost in half,就在那时 木星的干扰使其公转周期缩短将近一半 meaning it’ll come by again in just over 2,000 years!意味着它最快将于二千多年后回归 And just to keep us on our toes, Jupiter’s gravity can also pluck rocks from the Asteroid Belt需要警惕的是 木星引力可以将岩石从小行星带剥离 and send them our way too—which isn’t very neighborly!朝地球扔来 这不是好邻居该做的 But even if we have to give Jupiter a little side-eye now and then,不过尽管我们不得不经常对木星侧目 it could have helped make life on Earth possible.它有可能帮助了地球生物出现 During the formation of the solar system, 太阳系形成之初 its enormous gravity likely helped carve space for our planet to form in the first place.首先 木星巨大的引力可能为地球的形成创造了空间 And even when Jupiter seemed like our enemy,尽管木星看起来像敌人 the space debris it sent our way during Earth’s early years地球形成初期 木星送过来的太空碎片 may also have delivered organic material that helped life form.可能含有机物 帮助孕育生命 So thanks, Jupiter, for helping to get us going early on!所以 谢谢你木星 帮助我们早期出现 You can stop sending us all those asteroids and comets, though.不过 你可以停止向我们扔小行星和彗星了 Beyond helping us learn how to defend our own planet, 除了帮助我们学习如何保卫地球之外 understanding Jupiter’s role in our solar system could help us search for life beyond it.弄清木星在太阳系中的职能可以帮助我们搜寻太阳系外的生命 When we look for habitable worlds orbiting other stars,在我们寻找围绕其他恒星公转的宜居行星时 it might be useful not just to look for Earth-like planets, 不要只关注类地行星 but also to see what a Jupiter-like frenemy might be up to nearby.也看看附近亦敌亦友的类木行星会比较好 Thanks for watching this episode of SciShow Space!感谢观看本期《太空科学秀》 If you want to learn more about how Jupiter tosses its weight around in the solar system,如何你想知道更多关于木星如何在太阳系“减重” you might like our video about the group of asteroids Jupiter has held prisoner你可能会喜欢我们的视频 木星“囚禁”的小行星群 —possibly for billions of years!可能已经“囚禁”了几十亿年 You can find out more about Jupiter’s Trojan asteroids after this.之后你可以了解更多关于木星的特洛伊小行星介绍 [OUTRO ♪][结束曲]
  • 2021-09-07为什么船会浮在水面上?大家好!嘿,Squid在这儿啊!一切还好吗?Hey guys! Hey there, Squid! How’s it going? 唔唔唔,我现在有那么点异常情况。TGS: Mmmph. I’m kinda cranky right now. 噢,不。没有人想那样。是什么在困惑着你?Jessi: Oh no. No one wants that. What’s bothering you? 巡航舰TGS: Cruise ships. 巡航舰?Jessi: Cruise ships? 是的,巡航舰。你知道的,人们会用来到处航行的那些巨型的舰船。TGS: Yeah, cruise ships. You know, those giant boats that you people sail around in. There’s 他们整天在我上面开来开去,我根本没法睡觉。been one floating above me all day, and I can’t get any sleep! 我是说,他们非常大!而且特别吵闹!就像是一个漂浮的城市!I mean, it’s huge! And noisy! It’s like a floating city! 所以,我没有睡觉,只是醒着,四周游荡,瞪着巡航舰,想着为什么。So, instead of sleeping, I’ve just been bobbing awake, staring at it, and wondering. 这么巨大的一艘船是怎样在水上漂浮的呢?How does a giant ship like that float on the water? 我是说,通常情况下重的东西会沉到水底,是这样吧?就像有人扔石子I mean, heavy things sink in water, right? Like when someone up there tosses a rock into 到海里——你知道的,有时候会发生这种事——然后石子会沉入水底。the ocean — which happens, you know — it sinks. 所以说为什么那么重的船能浮起来呢?So why does that heavy ship get to float? 又大又重的船能浮起来和它的形状有关。Jessi: The reason a big, heavy ship like that can float has to do with its shape. 物体的是沉下去还是浮起来有很大一部分影响是来自于Whether an object sinks or floats to begin with has a lot to do with something called 排水量。displacement. 排水量指的是物体在水中排出或移开了多少水。所以说,当你Displacement is when an object displaces, or pushes aside, water. So, like, when you 把冰块放进一杯装满水的玻璃杯里面,会有一些水溢出来。drop an ice cube into an already-full glass of water, some water spills out. 那就是排水量吗?TGS: That’s displacement? 是的——溢出的水的量与Jessi: That’s right — the amount of water that spills out is actually equal to the amount 冰块占据的体积是相等的!of space the ice cube takes up! 或者想想你洗澡的时候。Or think about when you take a bath. 停一下。等等。洗澡是什么?TGS: Hold up. Wait. What’s a bath? 事实上,在陆地上,我们喜欢把自己浸湿在一大盆温暖的水里来清洁身体,Jessi: Well, up here, we like to clean ourselves up by soaking in a tub full of nice warm, 用上肥皂。soapy water. 听上去好粗野!那是不是说你们人类就是每天都要到处走弄得脏兮兮的?TGS: That sounds gross! Do that mean that humans just walk around all day getting dirty? 如果你们都能想我一样所有时间都在水里度过,你就不会弄脏,If you spent all of your time in the water like me, you’d never get dirty in the first 最开始就不会。place. 又不是每个人都是相同的,对吧?我知道肯定有一些在看视频的人知道Jessi: Well, not everyone’s the same, right? I know some of the people watching here know 洗澡是什么的。what a bath is. 好吧好吧。TGS: Mmmrph, okay. 所以,比如说你把浴缸加满水-加到最满。然后你跳进浴缸。Jessi: So, say you fill the bathtub up — all the way to the top. And then you climb in. 现在有水在地板上,很多水。水的体积Now there’s water on the floor. Lots of water. The amount of water equal to the amount 等同于你所占据的空间的体积of space that you took up! 一个物体之所以能飘浮的秘密在于,它必须置换足够的水Now, one of the secrets to an object being able to float, is that it has to displace 以便水能尽量的将它托起enough water so that the water it pushes aside weighs as much as it does. 好的,你在桶里,你想做个实验,你可以Alright, so, say you’re in the tub and you want to do an experiment. You can bring in 带一个小碗,一些岩石收藏品里的石头。a small bowl, and some rocks from your rock collection. 如果你把碗放入水中,它将浮起来,因为碗的底部置换了If you put the bowl in the water, it’ll float. Because the bottom of the bowl is displacing 一些水。水的体积和将碗托起的体积是一样的some water. And the amount of water that it’s pushing aside weighs the same as the bowl. 现在,我们将一个小石头放进去碗里Now, drop a little rock in there. 放进一个,再加一个Add another, and another. 碗变得越来越重了,所以每次都有点往下沉The bowl is getting heavier, so it’s sinking a little bit each time. 但即使碗越来越重,它同时也置换了更多的水But even though the bowl is heavier, it’s also displacing more water — so the amount 水的体积和将碗托起的体积是相同的of water that it’s pushing aside still weighs the same as the bowl. 那么巡航舰怎么解释?它为什么没有沉下去?TGS: So what does that mean for the cruise ship? Why doesn’t it sink? 嗯,轮船被设计得能排开尽可能多的水Jessi: Well, ships are designed to displace as much water as possible. 它们非常非常宽,并且它们的底部延伸得非常远,所以它们推开They’re realllly wide, and their bottoms tend stretch down really far, so they push 大量的水aside a lot of water. 另外,一艘轮船在它的内部有着很大的空间–它的很多地方是中空的–这帮助Plus, a ship has lots of empty space inside it — a lot of it is hollow — which helps 它保持轻,以及与被它所置换的、总量巨大的水比较to keep it light, compared to the huge amount of water that it’s displacing. 瞧…它浮起来了And voila… it floats. 好吧,好吧。所以现在在我头上那么大而且吵闹的聚会正在排出足够TGS: OK, OK. So that giant, noisy party over my head right now is displacing enough water 能使它浮起来的水that it can float. 噢,你们人类可能就是吵闹的,但是你们能够想出怎样建造能够漂浮巨大的金属东西Well, you people may be noisy, but the fact that you figured out how to build giant metal 的事实……非常聪明。我会给你们那个评价things that float… that’s pretty clever, I’ll give you that. 对,我并不了解你,但是我喜爱的一些东西往往是聪明Jessi: Yeah, and I don’t know about you, but some of my favorite things tend to clever 并且吵闹的。谢谢加入乌贼和我,学习排水量。下次and noisy. Thanks for joining Squid and me, learning about displacement. See you next 见time! 旅途愉快TGS: Bon voyage!

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