If superpowers were real: Flight - Joy Lin

譯者: Charlene Tsai 審譯者: Geoff Chen

If humans could fly,

如果人類能在不依靠任何工具

without tools and machines,

或機器的情況下飛行

how fast do you think we would go?

你認為我們能飛多快？

As of 2012, the world record

2012 年的世界紀錄中

for fastest short-distance sprint speed

短跑最快的

is roughly 27 miles per hour.

大約時速 43 公里（27 英哩）

Running speed depends on how much force

跑步的速度視跑者的腿

is exerted by the runner's legs,

能發揮多少力量

and according to Newton's Second Law of Motion,

根據牛頓第二運動定律

force is the product of mass times acceleration.

力量是物體質量乘上加速度

And Newton's Third Law states

牛頓第三定律則顯示

that for every action,

每個動作

there is an equal and opposite reaction.

都會有相同的反作用力

So, that means running requires

所以這表示跑步需要

having a ground to push off from,

地面讓跑者施力

and the ground pushes back against the runner's foot.

也以同樣的力量推向跑者的腳

So, flying would actually be

飛行實際上

more similar to swimming.

會比較像游泳

Michael Phelps is currently the fastest human in water

Michael Phelps（美國奧運游泳選手） 是目前游泳最快的人

and the most decorated Olympian of all time.

也獲得最多奧運金牌

Guess how fast he swims?

你猜他能游多快？

The answer may surprise you.

答案可能讓你很驚訝

His fastest recorded speed is

他最快的記錄

less than 5 miles per hour.

時速低於 8 公里（5 英哩）

A child on the ground can easily outrun

一個在地面跑步的小孩

Michael Phelps in water,

都可以輕易超過 Michael Phelps 在水中前進的速度

but why is that?

但為何會這樣呢？

Well, let's go back to Newton's Third Law of Motion.

讓我們再回到牛頓的第三運動定律

When we run, we move forward

當我們跑步時

by pushing against the ground with our feet

藉由雙足推向地面的力量前進

and the ground pushes back,

地面也回施力量

propelling us forward.

推動我們前進

The ground is solid.

地面是固體

By definition, it means the particles

顯然地，這表示

are essentially locked into place

粒子的本質是固著不動的

and must push back instead of getting out of the way,

所以一定會把力量推回，而不是被推開

but water is liquid and flows easily.

但水是液體，易於流動

When we move our limbs

當我們移動四肢

to push back against the water,

去推動水的時候

a part of the water molecules

部分的水分子

can just slide past one another

就會滑開

instead of pushing back.

並不會把力回推

Now, let's think about flying.

現在我們來思考關於飛行

Air has a lot more free space

空氣中有更多的空間

for particles to move past one another,

能讓分子移動

so even more of our energy would be wasted.

所以我們就會耗掉更多的能量

We would need to push a lot of air backwards

我們得要把很多的空氣向後推

in order to move forward.

才能前進

Astronauts move around in shuttles

宇航員在太空梭裡

in zero gravity when they're in outer space

外太空無重力的狀態下

by pulling on handles installed on the ceiling walls

他們要拉住安裝在牆上或地板上的把手

and floors of the shuttle.

才能移動

Now, imagine you were given the ability to float.

現在想像你能漂浮

How would you move around in the middle of the street?

你要怎樣在路中間移動呢？

Well, you wouldn't get very far

光靠著在空氣中游泳

by swimming in air, would you?

你沒辦法前進多少的，不是嗎？

Nah, I don't think so!

喔，我可不認為你能有多快

Now, assuming you were granted the ability to float

現在假設你能漂浮

and the speed to move around efficiently,

也能很有效率的四處移動

let's discuss the height of your flight.

那讓我們來討論飛行的高度

According to the Ideal Gas Law,

根據理想氣體方程式（Ideal Gas Law）

P-V N-R-T,

壓力 (P)、體積 (V)、莫爾數 (n) 理想氣體常數 (R) 與絕對溫度 (T)

pressure and temperature has a positive correlation,

壓力和溫度是正相關

meaning they increase and decrease together.

表示它們會同時升高或降低

This is because the air expands in volume

這是因為空氣在較小的壓力下

with less pressure,

體積會膨脹

so the molecules have more room to wander around

所以分子能有更多空間游移

without colliding into each other and creating heat.

而不會彼此碰撞產生熱能

Since the atmospheric pressure is a lot lower

既然在高空中

in high altitudes,

大氣壓力低得多

it would be freezing cold

溫度會變得很低

if you were flying above the clouds.

你要在雲上飛行的話

You'd need to wrap yourself up

你得把自己包得緊緊的

to keep your core body temperature

才能讓體溫

above 95 degrees Fahrenheit,

不低於攝氏 35 度（華氏 95 度）

otherwise you'd start shivering violently,

否則你會開始不停的發抖

gradually becoming mentally confused

然後神智不清

and eventually drop out of the sky

最後因為低溫造成

due to loss of muscle control

肌肉失控

from hypothermia!

從天上掉下來

Now, the Ideal Gas Law implies

依照理想氣體方程式（Ideal Gas Law）

that as the pressure decreases,

當壓力降低

gas volume increases.

氣體的體積會增加

So, if you were to fly straight up too quickly,

所以如果你一下子飛太高

你體內的惰性氣體會急速擴大

the inert gas in your body would rapidly expand

the way soda fizzes up when shaken.

就像汽水被搖過之後嘶嘶作響

The phenomenon is called "the bends,"

這現象叫做 「減壓症」（the bends）

decompression sickness,

因為減壓造成的疾病

or "divers disease"

又叫「潛水夫病」（divers disease）

since deep sea scuba divers experience this

用水肺游到深海的潛水伕 如果太快浮上水面

when they come up too quickly.

就會經歷相同的情況

This results in pain,

這會造成疼痛

paralysis,

癱瘓

or death,

甚至死亡

depending on how foamy your blood becomes.

端看你體內血液中氣泡量有多少

Okay, well, let's say you want to fly

好吧，那我們假設你只想

just a few meters above the ground

在離地幾公尺的地方飛行

在你還能看到道路標示的高度

where you can still see the road signs

and breath oxygen with ease.

也能輕鬆的呼吸到氧氣

You'll still need goggles and a helmet

你還是需要風鏡和安全帽保護

to protect you from birds,

因為會有鳥類

insects,

street signs,

昆蟲

街道標示

electrical wires,

電線

and other flying humans,

還有其他飛行中的人們

including flying cops

包括飛行警察

ready to hand you a ticket

等著要開你罰單

if you don't follow the flying rules, buddy.

如果你沒遵守飛行規則的話

Now remember, if you have a collision mid-air

要記得，如果你在半空中碰撞

that knocks you unconscious,

導致昏迷

you would experience free fall

你會變成自由落體

until you hit the ground.

直到撞上地面

Without society or the laws of physics,

如果沒有社會規範或是物理定律

flying would be a totally awesome ability to have.

那飛行真的是種超棒的能力

But, even if we could all just float around

但是，即使我們只能在

a few feet above the ground

離地幾公尺的地方漂浮

and only moving at a snail's pace,

用蝸牛般的速度前進

I'm telling you, it's still a cool ability that I'd want,

我跟你說，我依然想 擁有這種很酷的能力

wouldn't you?

你也是吧？

Yeah, I thought so.

沒錯，我也這麼想

Now, which superpower physics lesson

接下來，你想探索

will you explore next?

哪個超能力物理學課程？

Shifting body size and content,

改變身體大小和成分？

super speed,

超高速？

flight,

飛行能力？

super strength,

超級大力士？

immortality,

永生不死？

and

或是

invisibility.

隱形力？