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  • Let's start this video by throwing a mouse, a dog, and an elephant

    讓我們把一隻老鼠、小狗和大象往下丟來開始影片

  • from a skyscraper onto something soft.

    從摩天大樓到某種軟的東西上

  • Let's say, a stack of mattresses.

    像是⋯⋯床墊好了

  • The mouse lands and is stunned for a moment,

    老鼠著地後愣了一下

  • before it shakes itself off,

    然後會過神來

  • and walks away pretty annoyed,

    不爽地走開了,

  • because that's a very rude thing to do.

    因為這是一件非常粗魯的事情。

  • The dog breaks all of its bones

    狗全身骨折

  • and dies in an unspectacular way,

    悄悄地死去

  • and the elephant explodes into a red puddle of bones and insides

    而大象粉身碎骨,只剩一灘肉泥和內臟

  • and has no chance to be annoyed.

    連生氣的機會都沒有

  • Why does the mouse survive,

    為什麼老鼠活了下來

  • but the elephant and dog don't?

    但大象跟狗則不?

  • The answer is size.

    尺寸是關鍵

  • Size is the most underappreciated regulator of living things.

    尺寸是最被小看的生物特徵。

  • Size determines everything about our biology,

    它決定了生物學上的一切

  • how we are built, how we experience the world, how we live and die.

    從我們由什麼構成,我們如何體驗這世界,到出生、死亡的方式

  • It does so because the physical laws are different for different sized animals.

    原因是,物理定律對不同大小的動物有不同的表現

  • Life spans seven orders of magnitude, from invisible bacteria to mites, ants,

    生命的尺寸橫跨七個等級,從看不見的細菌到塵蟎、螞蟻、

  • mice, dogs, humans, elephants and, blue whales. Every size lives in its own

    老鼠、狗、人類、大象、藍鯨。各種規模的生物在彼此之間

  • unique universe right next to each other, each with its own rules, upsides, and

    獨特的宇宙生存。每一個都有自己的規則、優勢

  • downsides. We'll explore these different worlds in a series of videos. Let's get

    和缺點。我們將在一系列影片中探討這些不同的世界。讓我們

  • back to the initial question: Why did our mouse survive the fall? Because of how

    回到最初的問題:為什麼老鼠可以在下落中生存?因為

  • scaling size changes everything; a principle that we'll meet over and

    尺寸改變了一件事,一個我們會不斷在見到的原則,

  • over again. Very small things, for example, are practically immune to falling from

    非常小的東西從高處掉落實際上是不受傷害的

  • great heights because the smaller you are the less you care about the effect

    因為你越小,受到重力的影響也越低

  • of gravity. Imagine a theoretical spherical animal

    想像一下,一個假想的球形動物

  • the size of a marble. It has three features: its length, its surface area,

    有彈珠的大小。它有三個特徵:長度、表面積(覆蓋在皮膚上)

  • (which is covered in skin) and its volume, or all the stuff inside it like organs,

    和它的體積,或裡面全部的東西例如器官

  • muscles, hopes and dreams. If we make it ten times longer, say the size of a

    肌肉、希望和夢想。如果我們將其增長十倍,如籃球的大小

  • basketball, the rest of its features don't just grow ten times. Its skin will

    它的特徵可不只增長十倍。它的皮膚會

  • grow 100 times and it's inside (so it's volume) grows by 1000 times. The volume

    增加100倍,體積增長1000倍。

  • determines the weight, or more accurately, mass of the animal. The more mass you

    體積決定重量,或者更準確地說,動物的質量。你的質量越大

  • have, the higher your kinetic energy before you hit the ground and the

    你撞到地面前的動能也越高

  • stronger the impact shock. The more surface area in relation to your volume

    衝擊也更強。你的表面積(與體積和質量有關)越大

  • or mass you have, the more the impact gets distributed and softened, and also

    影響越被分散和緩和,也有

  • the more air resistance will slow you down. An elephant is so big that it has

    更多的空氣阻力讓你減速。大象是如此之大,它的

  • extremely little surface area in ratio to its volume. So a lot of kinetic energy

    表面積與體積的比非常小。所以極大的動能

  • gets distributed over a small space and the air doesn't slow it down much at all.

    被分佈在一個狹小的空間且空氣阻力減速程度不高

  • That's why it's completely destroyed in an impressive explosion of goo when it

    這就是為什麼它擊中地面時在爆炸當中被

  • hits the ground. The other extreme, insects, have a huge surface area in

    徹底摧毀。另一個極端的生物,昆蟲,表面積與體積的比

  • relation to their tiny mass so you can literally throw an ant from an airplane

    相對較大,你可以把一隻螞蟻從飛機上丟下

  • and it will not be seriously harmed. But while falling is irrelevant in the small

    而牠得以倖存。雖然墜落在微小世界中無關緊要,

  • world there are other forces for the harmless for us but extremely dangerous

    但有其他力量對我們無害,卻對小生物

  • for small beings. Like surface tension which turns water into a potentially

    特別危險。例如表面張力,把水變成對昆蟲

  • deadly substance for insects. How does it work? Water has the tendency to stick to

    致命的潛在陷阱。為何?水有相吸的特性

  • itself; its molecules are attracted to each other through a force called

    水分子會藉由凝聚力彼此吸引

  • cohesion which creates a tension on its surface that you can imagine as a sort

    在其表面形成一股張力,可以想像成一層

  • of invisible skin. For us this skin is so weak that we don't even notice it

    隱形皮膚。對我們而言這層皮膚很無力,甚至平常不會注意到。

  • normally. If you get wet about 800 grams of water or about one percent of your

    當你全身溼透,約800公克(或體重1%)的水

  • body weight sticks to you. A wet mouse has about 3 grams of water sticking to

    會黏在你身上。一隻溼透的老鼠則約有3公克的水

  • it, which is more than 10% of its body weight. Imagine having eight full water

    附著在牠身上,超過其體重的10%。想像一下有八瓶裝滿的

  • bottle sticking to you when you leave the shower. But for an insect the force

    寶特瓶,在你洗完澡後綁在你身上。但對於昆蟲,

  • of water surface tension is so strong that getting wet is a question of life

    水的表面張力是如此強,讓碰水變成一個攸關生死

  • and death. If we were to shrink you to the size of

    的問題。如果我們把你縮小到螞蟻

  • an ant and you touch water it would be like you were reaching into glue. It

    的大小,再讓你碰水,那就像碰到一團黏膠。

  • would quickly engulf you, its surface tension too hard for you to break and

    它會很快把你吞進去,由於表面張力太難打破

  • you'd drown. So insects evolved to be water repellent. For one their exoskeleton is

    你會被淹死。所以昆蟲演化出防水功能,其中之一是牠們的外骨骼

  • covered with a thin layer of wax just like a car. This makes their surface at

    包覆著一層薄臘,就像車子,讓牠們的體表

  • least partly water repellent because it can't stick to it very well. Many insects

    至少部分防水,因為它無法完美黏附體表。許多昆蟲

  • are also covered with tiny hairs that serve as a barrier. They vastly increase

    也覆蓋著細毛當作阻擋。大大增加了

  • their surface area and prevent the droplets from touching their exoskeleton

    它們的表面積及防止水滴觸碰自己的外骨骼

  • and make it easier to get rid of droplets. To make use of surface tension

    並更容易擺脫它。為了利用表面張力

  • evolution cracked nanotechnology billions of years before us. Some insects

    演化搶先我們數十億年破解奈米科技。有些昆蟲

  • have evolved a surface covered by a short and extremely dense coat of water

    已經演化成擁有由密集短毛構成的

  • repelling hair. Some have more than a million hairs per square millimeter when

    防水外套,有些光是每平方毫米就有上百萬根毛。當

  • the insect dives under water air stays inside their fur and forms a coat of air.

    昆蟲潛水時,空氣停留在短毛內並形成空氣的外膜。

  • Water can't enter it because their hairs are too tiny to break its surface tension.

    水無法進入,因為牠們的毛髮太細密了,無法打破水的表面張力。

  • But it gets even better, as the oxygen of the air bubble runs out, new oxygen

    但不只如此,外膜中的氧氣用完時,新的氧氣

  • diffuses into the bubble from the water around, it while the carbon dioxide

    從周圍的水擴散到膜內,而二氧化碳

  • diffuses outwards into the water. And so the insect carries its own outside lung

    向外擴散到水中。所以昆蟲能到處帶著自己的外肺

  • around and can basically breathe underwater thanks to surface tension.

    並基本上能在水下呼吸。一切受惠於表面張力

  • This is the same principle that enables pond skaters to walk on water by the way,

    順道一提,水黽能在水面上行走也是靠相同的道理

  • tiny anti-water hairs. The smaller you get the weirder the environment becomes. At

    防水細毛。你體型越小,環境也變得越怪異。在

  • some point even air becomes more and more solid. Let's now zoom down to the

    某些時候甚至連空氣變得越來越更加黏稠。現在,讓我們放大來到

  • smallest insects known, about half the size of a grain of salt,

    已知最小的昆蟲,大約有一粒鹽一半大小

  • only 0.15 millimeters long: the Fairy Fly. They live in a world even weirder than

    僅有0.15毫米長:纓小蜂。他們生活的世界,甚至比其他昆蟲

  • another insects. For them air itself is like thin jello, a syrup-like mass

    都還來的怪異。對牠們來說,空氣本身就像果凍,糖漿般的物質

  • surrounding them at all times. Movement through it is not easy. Flying

    時時圍繞他們,在其中活動相當不容易。飛行

  • on this level is not like elegant gliding; they have to kind of grab and

    在這個尺度上可不像優雅地滑翔,牠們必須像攀附在

  • hold onto air. So their wings look like big hairy arms rather than proper insect

    空氣上。因此牠們的翅膀就像長毛的手臂,而非普通昆蟲的翅膀。

  • wings. They literally swim through the air, like a tiny gross alien through

    牠們確實是「游」過空氣,就像奇異的長毛外星人

  • syrup. Things only become stranger from here on

    游過糖漿。當我們探索更多不同尺度,

  • as we explore more universes of different sizes. The physical rules are

    事情只會變得更奇怪。物理法則在每個地方

  • so different for each size that evolution had to engineer around them

    的不同,讓演化必須不斷解決這些問題

  • over and over as life grew in size in the last billion years. So why are there

    讓生命數十億年來持續繁盛。所以為什麼

  • no ants the size of horses? Why are no elephants the size of amoeba? Why?

    沒有像馬那麼大的螞蟻?為什麼沒有像阿米巴原蟲尺寸的大象?為何?

  • We'll discuss this in the next part.

    我們將在下一部影片討論這個問題。

  • We have a monthly newsletter now, sign up if

    我們現在有每月電子報了!

  • you don't want to miss new videos and for bonus videos.

    如果你不想錯過新的影片和會員專屬影片,就註冊吧

Let's start this video by throwing a mouse, a dog, and an elephant

讓我們把一隻老鼠、小狗和大象往下丟來開始影片

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B1 中級 中文 英國腔 昆蟲 大象 表面積 體積 空氣 老鼠

要是從摩天大樓丟下一隻大象會發生什麼事?:生命與體型1 (What Happens If We Throw an Elephant From a Skyscraper? Life & Size 1)

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    汪摳 發佈於 2017 年 08 月 19 日
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