如何讓一頭大象爆炸——生命的尺度 2：英語精讀講義

Let's shrink an elephant to the size of a mouse and enlarge a mouse and make it the size of an elephant

讓我們把大象縮小到老鼠那麼大，再把老鼠放大到大象那麼大，

because this is our video and we want to see what happens.

因為這是我們的影片，我們想看看會發生什麼事。

First, our now tiny elephant stumbles around and then drops dead. 片語搭配

首先，我們現在這隻小象踉蹌了幾步，然後倒地身亡。

Tiny elephant buddy is very cold,

小象夥伴覺得非常冷，

frozen to death in minutes. 片語搭配

幾分鐘內就凍死了。

Our giant mouse looks very uncomfortable for a moment

我們巨大的老鼠有一瞬間看起來非常難受，

and then it explodes,

然後牠爆炸了，

leaving hot mouse insides everywhere. 文法

留下到處都是滾燙的老鼠內臟。

Why?

為什麼？

Because of size.

因為體型。

We are optimized to function precisely for the size we are

我們的身體經過了最佳化，能精確適應我們現有的體型，

and would die horribly in any other environment.

如果換成其他體型，就會死得很慘。

But why exactly?

但究竟是為什麼呢？

Why does our mouse explode

為什麼我們的老鼠會爆炸，

and can we do this to our elephant too

並且如果我們努力嘗試，

if we try hard?

能不能讓大象也爆炸？

Life on this planet is based on cells.

地球上的生命都是由細胞構成的。

Cells do vary in size,

細胞的大小確實各不相同，

but they're pretty similar in their dimensions across all species.

但在所有物種中，它們的尺寸其實都相差無幾。

A blue whale doesn't have bigger cells than a hummingbird, 文法

藍鯨的細胞並不比蜂鳥的大，

just a lot more of them.

只是數量多了很多。

Cells have to do a lot of stuff to stay alive

細胞必須做很多事情才能保持存活，

and they need energy to be able to do so. 片語搭配

並且它們需要能量才能做到這一點。

To get this energy,

為了獲取能量，

animal cells convert food and oxygen into usable chemical energy. 片語搭配

動物細胞將食物和氧氣轉化為可用的化學能。

This happens in our mitochondria,

這個過程發生在我們的粒線體中，

the powerhouse of the cell. 慣用語

即細胞的動力庫。

They're like little coal engines that spit out tiny ATP batteries, 片語動詞

它們就像小型煤炭引擎，吐出微小的 ATP 電池，

which the cell can use for almost everything it needs to do.

細胞幾乎可以用它來完成所有需要做的事情。

Just like an engine,

就像引擎一樣，

mitochondria get really hot while working.

粒線體在運作時會變得很熱。

In human skin cells,

在人類皮膚細胞中，

they reach a scorching 50 degrees Celsius.

它們能達到攝氏 50 度的高溫。

And some of our cells have up to 2,000 mitochondria,

我們有些細胞擁有多達 2000 個粒線體，

which are radiating their heat into the cell.

它們都在向細胞內散發熱量。

So being alive generates a lot of heat.

因此，活著就會產生大量熱量。

The more cells you have, 文法

你的細胞越多，

the more heat your body generates in total.

你的身體總共產生的熱量就越多。

If our bodies didn't find ways of losing this heat, 文法

如果我們的身體找不到散發這些熱量的方法，

we would be cooked from the inside and die.

我們就會從內部被煮熟並死去。

But this is a problem for bigger animals

但對於大型動物來說是個問題，

because of the way bodies change as living beings scale up. 片語動詞

因為隨著生物體型變大，身體的比例會發生變化。

Animals have three properties here that are important.

動物有三個重要的屬性：

Their length,

牠們的長度、

their outsides or skin,

外部（或皮膚），

and their insides, like organs, bones,

以及內部，例如器官、骨骼，

and hopes and dreams.

還有希望與夢想。

The thing that's hard to wrap your head around is 慣用語

難以理解的是，

that when things grow,

當物體變大時，

their insides grow faster than their outsides.

它們內部的生長速度要快於外部。

Imagine a fleshy cube.

想像一個肉乎乎的立方體。

If you double the length of its sides,

如果你將其邊長增加一倍，

its surface and volume do not double.

它的表面積和體積並不會只增加一倍。

In fact, 表達脈絡

事實上，

the surface is now four times the original size 文法

表面積現在是原來的四倍，

and the volume of the cube eight times the original size.

而立方體的體積則是原來的八倍。

Which is called the square cube law 文化背景

這被稱為平方立方定律，

and has been annoying nature for billions of years. 慣用語

幾十億年來一直讓大自然很頭痛。

So why is this a problem for big animals?

那麼，為什麼這對大型動物是個問題呢？

Because heat can only leave an object via its surface.

因為熱量只能透過物體的表面散發。

So if we make our mouse the size of an elephant

所以如果我們把老鼠變得和大象一樣大，

or 60 times longer,

或者說長度增加 60 倍，

it has 3,600 times more surface from which to lose heat. 文法

牠的散熱表面積增加了 3600 倍。

But it has 216,000 times more volume

但牠的體積增加了 216000 倍，

filled with trillions and trillions of new hot mitochondria 片語搭配

裡面充滿了數以萬億計的全新的、滾燙的粒線體，

that produce more heat.

產生著更多的熱量。

A lot more insides; 表達脈絡

內部增加了非常多；

not that much more skin.

皮膚卻沒有增加那麼多。

Our mouse is very dead,

我們的老鼠死透了，

very fast.

而且死得非常快。

But big things like elephants exist,

但像大象這樣的大型生物是存在的，

so how do they deal with the heat? 片語動詞

那麼牠們是如何處理熱量的呢？

For one, 表達脈絡

首先，

they evolved ways to get rid of energy more easily, 片語動詞

牠們演化出了更容易散發能量的方法，

like huge flat ears

比如巨大扁平的耳朵，

that have a lot of surface where heat can escape.

有著很大的表面積可以讓熱量散發。

But that's not enough.

但這還不夠。

Nature's solution is actually very elegant.

大自然的解決方案其實非常巧妙。

Elephant cells are much, 文法

大象細胞的運作速度，比老鼠細胞要

much slower than mice cells.

慢得多。

The bigger an animal is, 文法

動物越大，

the less active its cells are.

其細胞的活躍度就越低。

If we classify animals by their metabolic rates 片語搭配

如果我們將動物按代謝率分類，

and compare that to their overall mass, 片語搭配

並將其與牠們的總質量進行比較，

it's clearly visible.

這一點就顯而易見了。

It's not 100% accurate,

雖然不是 100% 準確，

but it is a good rule of thumb. 慣用語

但這是一個很好的經驗法則。

Elephants are huge meat sacks

大象是巨大的肉袋子，

filled with trillions and trillions of little coal ovens. 慣用語

裡面裝滿了數以萬億計的小煤爐。

So they keep the ovens just active enough to keep them running 文法

所以牠們讓這些爐子保持剛剛夠用的活躍度，

and never at full power.

從來不全功率運轉。

Their whole metabolism is slow.

牠們的整體代謝很慢。

Things move at a nice chill pace. 用詞

一切都以一種悠閒的節奏進行著。

Small animals need to go the exact opposite way. 片語搭配

小動物則需要走完全相反的路。

If you're small,

如果你很小，

you have a lot of surface area compared to not a lot of volume.

與很小的體積相比，你的表面積很大。

You don't have a lot of cell ovens

你沒有那麼多的細胞火爐，

and lose the heat they produce very fast.

並且熱量散失得非常快。

So very tiny mammals came up with a very extreme solution. 片語動詞

因此，非常微小的哺乳動物想出了一個極端的解決方案。

Meet the Etruscan shrew, 表達脈絡

看看伊特魯斯坎鼩鼱，

the smallest mammal on Earth.

地球上最小的哺乳動物。

A mole-like thing

牠長得像鼴鼠，

that's more closely related to hedgehogs than to mice. 文法

與刺蝟的親緣關係比老鼠更近。

With a body length of 4 cm, 文法

牠體長 4 公分，

it only weighs about 1.8 g,

體重只有約 1.8 克，

as much as a paperclip. 文法

和一個迴紋針差不多重。

It's a tiny ridiculous being.

這是一個荒謬的小生命。

It would basically cool off immediately,

牠基本上會立刻變冷，

so its cells run on overdrive to stay warm. 慣用語

所以牠的細胞要超負荷運轉來保持溫暖。

Its tiny ovens are filled at maximum capacity.

牠的微型火爐都在滿負載燃燒。

Its heart beats up to 1,200 times a minute 文法

牠的心跳每分鐘高達 1200 次，

and it breathes up to 800 times a minute.

呼吸每分鐘高達 800 次。

This creates an extreme need for energy,

這造成了對能量的極度需求，

so the shrew has to eat constantly.

所以這種鼩鼱必須不停地吃東西。

After only 4 hours without food,

只要 4 小時沒吃東西，

it starves to death.

牠就會餓死。

And while an African elephant consumes around 4% of its body weight in food each day,

雖然一頭非洲象每天消耗的食物約占其體重的 4%，

our shrew needs 200% of its body weight in food a day just to survive.

我們的鼩鼱每天需要吃掉相當於其體重 200% 的食物才能生存。

Imagine having to eat 2,000 Big Macs a day, 文法

想像一下每天要吃 2000 個大麥克，

more than one a minute.

每分鐘吃不止一個。

Fun for a while,

一開始可能挺好玩，

but then not so much. 語氣意圖

但之後就不怎麼好玩了。

So a cubic centimeter of shrew

因此，一立方公分的鼩鼱

needs 40 times more food than a cubic centimeter of elephant. 文法

需要的食物是一立方公分大象的 40 倍。

If an elephant's cells suddenly become as active as the cells of a shrew, 文法

如果大象的細胞突然變得和鼩鼱的細胞一樣活躍，

a crazy amount of heat would be generated.

就會產生瘋狂的熱量。

All the liquids in the elephant would suddenly start boiling

大象體內所有的液體會突然開始沸騰，

and then it would explode

然後牠會爆炸，

in an impressive explosion of steaming hot burning elephant parts.

在一場壯觀的爆炸中，炸出熱氣騰騰、燃燒著的大象碎塊。

In reality, 表達脈絡

在現實中，

before an explosion occurred,

在發生爆炸之前，

the proteins making up our cells 片語動詞

構成細胞的蛋白質

would probably be denatured and stop producing heat. 用詞

可能會發生變性並停止產生熱量。

But a meat explosion is much more fun

但肉塊爆炸要好玩得多，

than melting an elephant into a massive hot goo.

比把大象融化成一大灘滾燙的黏液有趣。

Regardless, 表達脈絡

無論如何，

the scaling of the speed of metabolism happens everywhere,

代謝速度與體型的比例關係無處不在，

even in places we don't expect,

甚至在我們意想不到的地方，

like pregnant women.

比如孕婦。

A baby in the womb of its mother

母親子宮裡的嬰兒

behaves as if it were a part of her. 文法

表現得就像是她身體的一部分。

Its cells have about the same metabolic rate,

其細胞的代謝率，

the same speed of life,

也就是生命的速度，

as its mother's organs.

和母親的器官差不多。

It is truly a part of a bigger whole

牠確實是一個更大整體的一部分，

rather than an individual. 文法

而不是一個獨立的個體。

Until it's not anymore. 表達脈絡

直到牠不再是。

The very moment a baby is born, 文法

在嬰兒出生的那一刻，

a switch is flipped 慣用語

開關被按下，

and all its internal processes speed up rapidly. 片語動詞

牠的所有內部生理過程迅速加快。

36 hours after birth,

出生 36 小時後，

the baby's cells have the same activity rate as a mammal its size.

嬰兒細胞的活躍度就達到了同等體型哺乳動物的水平。

Babies literally transition from being an organ 片語搭配

嬰兒真的是在短短幾個小時內，

to being an individual in mere hours.

從一個器官轉變成了一個獨立的個體。

But there's one thing where big and small things are very similar,

但在有一點上，大動物和小動物非常相似：

Heartbeats.

心跳。

Mammals tend to have a similar amount of heartbeats over their lifetime, 文法

哺乳動物一生中的心跳總數往往是相近的，

typically around 1 billion.

通常在 10 億次左右。

So while the shrew and elephant are very different, 文法

所以，雖然鼩鼱和大象截然不同，

they share a similar number of heartbeats over the course of their lives. 片語搭配

但牠們一生中的心跳次數卻很相似。

Their speed of life is the opposite 表達脈絡

牠們生命的速度截然相反，

and somehow still the same.

卻在某種程度上依然相同。

And for a video in which we made elephants explode for no good reason, 片語搭配

作為一個無緣無故讓大象爆炸的影片，

this is the most romantic ending we could come up with.

這是我們能想到的最浪漫的結局了。