Free falling in outer space - Matt J. Carlson

在外太空自由落体 - Matt J. Carison

翻译人员: Diwen Tan 校对人员: Linghong Zhang

Have you ever been floating in a swimming pool,

你是否曾经漂浮在游泳池

all comfy and warm, thinking,

非常惬意，暖洋洋，遐想不断

"Man, it'd be cool to be an astronaut!

“天啦，当一名宇航员太爽了！

You could float out in outer space, look down at the Earth and everything.

你可以在外太空漂浮，

俯瞰地球以及所有的一切。

It'd be so neat!"

太棒了！“

只是事实并不如此。

Only that's not how it is at all.

If you are in outer space, you are orbiting the Earth:

如果你在外太空，

你将会绕地球转动，

这叫做自由落体。

it's called free fall.

You're actually falling towards the Earth.

事实上，你正朝着地球下落。

好吧，就此考虑一会儿。

Think about this for a moment: that's the feeling you get

你得到的感觉是这样的：

if you're going over the top of a roller coaster, going, like, "Whoa!"

就像你坐上云霄飞车，即将爬过顶端

冲吧 “喔喔哦哦~~·！”

Only you're doing this

只是这回你将一直这样

the whole time you're orbiting the Earth,

你将围绕着地球转动

两个

for two, three, four hours, days.

三个

四个

小时，

Whatever it takes, right?

好几天

无论怎样，对吧？

So, how does orbiting work?

那么，怎么旋转的呢？

Let's take a page from Isaac Newton.

让我们请教一下牛顿吧。

He had this idea, a little mental experiment:

他有这样一个想法，

一个小的心理实验。

You take a cannon,

你拿来一个大炮，

you put it on top of a hill.

把它摆在山顶上。

如果你发射炮弹，

If you shoot the cannonball,

it goes a little bit away.

射到不远处。

But if you shoot it harder,

但是如果你更猛地发射，

它将“嗖”的飞到足够远，以至于

it goes far enough so that it lands

a little bit past the curvature of Earth.

它降落在地球表面的曲度以外。

那么， 想象一下，

Well, you can imagine if you shot it really, really, hard,

倘若你非常非常猛地发射，

it would go all the way around the Earth

它也许会绕着地球飞行很远，

and come back -- boom! -- and hit you in the backside or something.

然后绕回来，砰！

好比，撞到你后背啥的。

让我们把焦点拉回太空

Let's zoom way back and put you in a little satellite

并把你放在

over the North Pole of the Earth

一个位于地球北极上方的小卫星里

and consider north to be up.

并设北极方向为正向上的。

You're going to fall down and hit the Earth.

你将会下落并撞向地球。

然而， 实际上你正在非常快速地向一旁移动。

But you are actually moving sideways really fast.

So when you fall down,

所以，当你下落的时候，

你不得不错过正下方。

you're going to miss.

You're going to end up on the side of the Earth, falling down,

你将最终移动到地球的一边，

你往下落，

and now the Earth is pulling you back in sideways.

而地球把你往一旁拉

So it's pulling you back in and you fall down,

也就是说，你被地球往下拉

同时你往正下方降落，

and so you miss the Earth again, and now you're under the Earth.

所以，你将再次错过地球。

这时，你已经移动到地球的下面。

The Earth is going to pull you up, but you're moving sideways still.

地球往上拉你，

但是你仍旧往一旁移动。

所以，你不得不再次错过地球。

So you're going to miss the Earth again.

现在，你已经移动到地球的另一边，

Now you're on the other side of the Earth, moving upward,

正往上移动，并且地球正把你拉向一边（垂直朝向地球），

and the Earth's pulling you sideways.

也就是说，你在往一边下落，

So you're going to fall sideways,

但是，你正在（快速地）向上移动，所以你再次错过（地球）。

but you're going to be moving up and so you'll miss.

现在，你再次回到了地球顶端，

Now you're back on top of the Earth again, over the North Pole,

北极上方，

going sideways and falling down,

往一旁移动，同时向下落，

and yep -- you guessed it.

是的，你已经猜到了。

你将一直错过（地球），因为你正在飞速地移动。

You'll keep missing because you're moving so fast.

In this way, astronauts orbit the Earth.

正是如此，宇航员围绕地球飞行。

They're always falling towards the Earth,

虽然他们一直朝地球下落，

but they're always missing, and therefore, they're falling all the time.

但他们却一直错过（落回地球），

因此，他们一直在下落。

They feel like they're falling, so you just have to get over it.

他们也感觉自己在下落，

你基本上只能接受这样一种感觉。

So technically, if you ran fast enough and tripped,

所以，技术上说，如果你跑得足够快， 突然绊一脚，

you could miss the Earth.

你将脱离地球。

但是，这里有个大问题。

But there's a big problem.

First, you have to be going eight kilometers a second.

第一，你必须每秒跑8公里。

That's 18,000 miles an hour,

也就是每小时18,000英里

just over Mach 23!

超过23马赫（23倍音速）！

The second problem:

第二个问题：

假设你能移动那么快，

If you're going that fast,

yes, you would orbit the Earth and come back where you came from,

是，你将绕地球运动

并且回到你的起点，

but there's a lot of air in the way,

但是一路上会有大量的空气，

much less people and things.

当然，极少有人和其他事物。

So you would burn up due to atmospheric friction.

所以，大气摩擦将导致你燃烧至尽

So, I do not recommend this.

因此，我并不推荐（这样做）。