為什麼地球是一座監獄以及如何逃離它：英語精讀講義

We are prisoners on Earth. 慣用語

我們是地球上的囚徒。

The universe taunts us 慣用語

宇宙在嘲弄我們，

by showing us all the places we can't ever visit.

向我們展示了那些我們永遠無法到達的地方。

However, if our species wants to have a long-term future, 文法

然而，如果人類想要有長遠的未來，

we have to escape our prison.

我們就必須逃離這座監獄。

But what's keeping us here in the first place? 片語搭配

可是，究竟是什麼把我們困在了這裡？

Turns out we owe the universe 講解

原來，我們欠了宇宙

a debt that is 4.5 billion years old.

一筆長達45億年的債務。

Everything with mass in the universe attracts every other thing with mass.

宇宙中所有有質量的物體都會吸引其他有質量的物體。

We call this phenomenon gravity.

我們把這種現象稱為重力。

The closer you are to a big chunk of mass,

離一塊大質量物體越近，

the stronger the attraction

吸引力就越強，

or the more you're pulled in.

也就是你被拉向它的力量越大。

This effect traps us on Earth.

這種效應將我們困在地球上。

We can imagine this as being prisoners in a gravity prison

我們可以把它想像成被困在重力監獄

or a gravity well. 文化背景

或者是重力井中的囚徒。

It's not a literal well, 文法

它不是一口真正的井，

but a handy concept to understand how this works.

而是一個方便理解其工作原理的概念。

Being in a gravity prison means

身處重力監獄意味著

that you owe gravity energy.

你欠了重力的能量。

But how can you owe energy?

但你怎麼會欠能量呢？

Because in our universe,

因為在我們的宇宙中，

things don't want to change their speed or direction.

物體不想改變它們的速度或方向。

To convince them to move,

為了迫使它們移動，

you have to expend energy. 片語搭配

必須消耗能量。

Billions of years ago,

數十億年前，

the gravitational attraction of trillions of trillions of dust particles

圍繞太陽運行的億萬塵埃顆粒之間的引力

orbiting our sun pulled them together

將它們拉到一起，

until they formed a planet. 文法

直到形成了一顆行星。

This process used energy

這一過程消耗了能量，

and created the gravity well we're now a part of.

並創造了我們現在身處的重力井。

The deeper you are inside a gravity well,

你在重力井裡陷得越深，

the more energy you owe gravity.

欠重力的能量就越多。

If you don't find a way to get enough energy,

如果你找不到獲取足夠能量的方法，

you're not able to leave,

你就無法離開，

no matter what you do. 文法

無論你做什麼。

Because your atoms were once part of the dust

因為你的原子曾經是那些塵埃的一部分，

that the universe expended energy on

宇宙正是消耗了能量，

to get to this place.

才把它們帶到了這裡。

Okay.

好吧。

Hmm.

嗯。

Let's summarize all of that again. 表達脈絡

讓我們重新總結一下。

Objects in the universe don't like to move.

宇宙中的物體不喜歡移動。

You have to convince them to do so with energy.

你必須用能量來迫使它們移動。

Gravity used energy

重力消耗了能量，

to convince the parts that make up our planet 片語動詞

迫使構成我們星球的各部分

to move together.

聚攏在一起。

This created a gravity prison in the process, 片語搭配

在這個過程中，它創造了一個重力監獄，

trapping us.

困住了我們。

To escape it,

要逃離它，

we need to repay it with energy.

我們需要用能量來償還。

Okay.

好。

How do we do that?

我們要怎麼做呢？

To get into space,

要進入太空，

we need to go through a complicated process 片語動詞

我們需要經歷一個複雜的

of exchanging energy.

能量交換過程。

For this purpose,

為此，

we build a negative potential energy repaying machines,

我們建造了「負位能償還機」，

known by their more boring name, 片語搭配

也就是名字更無趣的

rockets.

火箭。

Rockets work by using some of the most energetic chemical reactions humans know about 文法

火箭透過利用人類已知最劇烈的化學反應工作，

to basically explode fuel in a controlled way.

基本上就是以受控的方式引爆燃料。

This converts chemical energy into kinetic energy. 片語搭配

這將化學能轉化為動能。

The exhaust of the reaction is directed outwards

反應產生的廢氣向外排出，

and pushes the rocket away from Earth.

將火箭推離地球。

By expending a lot of energy, 文法

透過消耗大量能量，

we are increasing our gravitational potential energy,

我們正在增加自身的重力位能，

which is a complicated way 表達脈絡

這種說法有點複雜，

to say that we're paying back our energy debt to gravity.

實際上就是說我們在償還欠重力的能量債。

But it's actually a lot trickier than that.

但實際上事情要棘手得多。

When you burn fuel to get into orbit,

當你燃燒燃料進入軌道時，

you lose lots of energy to heat,

大量的能量會以熱能、

the exhaust,

廢氣，

and atmospheric drag, 用詞

和大氣阻力的形式流失，

so you actually need much more.

所以你實際上需要多得多的能量。

And you can't just pile a huge amount of really explosive dangerous fuel

而且你不能簡單地把一大堆極具爆炸危險的燃料

close to your payload

堆在酬載旁邊

and detonate it.

然後引爆。

You need a controlled burn, 用詞

你需要受控燃燒，

which is complicated and makes your rocket very heavy,

這是非常複雜的，而且會讓你的火箭變得很重，

which means it has more mass.

意味著它有更大的質量。

The more mass something has, 文法

物體的質量越大，

the more energy you need to convince it to move.

你就需要越多的能量來迫使它移動。

So you need more fuel to lift up your rocket.

所以你需要更多燃料來升起火箭。

But if you need more fuel,

但是如果需要更多燃料，

that means you need more rocket to carry that fuel.

這意味著你需要更大的火箭來裝載那些燃料。

But this makes your rocket heavier,

但這會讓你的火箭變得更重，

thus requiring more fuel, 文法

從而需要更多燃料，

which requires more rocket to carry that new fuel,

進而需要更大的火箭來裝載那些新加的燃料，

and so on. 片語搭配

如此循環。

At the end of this madness,

在這種瘋狂的惡性循環結束時，

you need closer to a 100 times the weight of your payload

你需要近乎酬載100倍的重量

to launch.

才能完成發射。

Ariane 6,

亞利安6號，

for example,

舉例來說，

the European rocket,

就是歐洲的一款火箭，

will weigh 800 tons

它重達800噸，

and should be able to transport 10 tons into geostationary transfer orbit

能夠將10噸酬載送入地球同步轉移軌道，

or 20 tons into medium Earth orbit.

或者將20噸送入中地球軌道。

But a rocket can only produce so much thrust, 文法

但一枚火箭產生的推力是有限的，

so there's a maximum weight

所以存在一個最大重量，

after which it just won't take off. 片語動詞

超過這個重量它就飛不起來。

If you add too much weight,

如果你增加過多重量，

it won't lift off,

它就無法升空，

so you can't just build bigger and bigger fuel tanks. 文法

所以你不能一直建造越來越大的燃料箱。

This is the tyranny of the rocket equation, 慣用語

這就是「火箭方程式的暴政」，

and it means spaceflight will never become easy.

它意味著太空飛行永遠不會變得容易。

But wait, 表達脈絡

但是等等，

it gets worse.

情況會更糟。

Getting to space is still not good enough.

進入太空仍不夠好。

You're still inside the gravity prison

你仍然處於重力監獄中

at the edge of space

在太空邊緣，

and will crash back to Earth.

而且還會墜回地球。

Staying in space 文法

留在太空

is much harder than getting there.

比進入太空難得多。

To get to a stable position

為了達到一個穩定位置

where it can stay for a while,

讓它能夠暫時停留一段時間，

the rocket has to reach low Earth orbit. 文化背景

火箭必須進入近地軌道。

To do this,

為此，

you need a lot of kinetic energy,

你需要巨大的動能，

which means going extremely fast.

也就是必須飛得極快。

At an altitude of about 100 km,

在大約100公里的高空，

this is 8 km per second,

這個速度是每秒8公里，

28,000 km per hour,

時速28000公里，

fast enough to travel around Earth 文法

快到足以繞地球一圈

in 90 minutes.

只需90分鐘。

Here,

在這裡，

we can use a trick.

我們可以用個把戲。

Instead of flying straight up, 文法

與其垂直向上飛，

we can go sideways.

不如向側面移動。

Earth is a sphere.

地球是一個球體。

So if you're going sideways fast enough,

所以如果你向側面移動得足夠快，

even though you're falling towards Earth, 文法

即使你正在跌向地球，

the ground will curve away beneath you.

地面會在你下方彎曲並遠離你。

So as long as you're above the atmosphere, 文法

所以只要你在大氣層之上，

about 100 km up,

也就是大約100公里高，

you'll be able to stay up there in orbit.

你就能留在上面，保持在軌道中。

This is what the ISS does,

國際太空站就是這樣做的，

falling around Earth, 文化背景

繞著地球「跌落」，

expending energy from time to time 片語搭配

時不時消耗一點能量

to stay fast enough.

以保持足夠快的速度。

If we look at orbits in scale,

如果我們按比例來看軌道，

we see that near Earth orbit is laughably close to Earth.

我們會發現近地軌道其實離地球非常近。

To deploy,

要部署

for example,

比如，

satellites or leave for other planets,

衛星，或者飛往其他行星，

requires another round of energy debt repayment. 片語搭配

就需要償還新一輪的能量債務。

Getting to orbit

進入軌道

is the most difficult part of spaceflight

是目前太空飛行中

for us right now.

對我們來說最困難的部分。

For example,

例如，

if we want to send a rocket to Mars,

如果我們想向火星發射火箭，

half the energy is necessary just to get into orbit,

一半的能量僅用於進入軌道，

and the other half for the 55 million km to Mars.

另一半用於飛向火星的5500萬公里。

Therefore,

因此，

to be as effective as possible, 文法

為了盡可能高效，

rockets aren't built in one giant piece.

火箭不會被建造成一個巨大的整體。

Instead,

相反，

we use multi-stage rockets. 文化背景

我們使用多節火箭。

You don't need to carry an empty fuel tank,

因為不需要攜帶空的燃料箱，

so rockets drop it.

所以火箭會將其拋棄。

Rockets today shed their boosters and main stage 用詞

如今的火箭會拋棄助推器和主級，

as they ascend,

在它們升空的過程中，

with each successive stage being its own fully contained rocket, 文法

連續的每一級本身就是一枚完全獨立的火箭，

complete with its own engine and fuel. 片語搭配

配備著自己的發動機和燃料。

Okay.

好吧。

So this is why getting to space 表達脈絡

這就是為什麼進入太空

is hard.

如此困難。

If you feel all of this seems really complicated,

如果你覺得這一切似乎真的很複雜，

don't worry.

別擔心。

It's literally rocket science. 慣用語

這真的就是「火箭科學」。

This video was made possible in part 片語搭配

本影片的部分製作資金

by a sponsorship by Airbus Safran Launchers and Arianespace,

得到了空中巴士賽峰發射器公司和亞利安空間公司的贊助，

who are getting their new Ariane 6 rocket

他們正準備將新的亞利安6號火箭

ready to launch

準備好發射

into space in 2020. You can learn more about the rocket here.

並在2020年送入太空。你可以在這裡了解更多關於該火箭的資訊。

And as always,

和往常一樣，

if you like what we do,

如果你喜歡我們的作品，

please consider supporting us on patreon.com.

請考慮在 patreon.com 上支持我們。

It really helps us out a lot.

這對我們幫助很大。

If you're craving more space stuff now,

如果你現在還想看更多有關太空的內容，

here's a playlist for you.

這裡的播放清單適合你。