Free falling in outer space - Matt J. Carlson

外太空的自由落體運動—馬特·卡爾森 (Matt J. Carlson)

譯者: 瑞文Eleven 林Lim 審譯者: Regina Chu

Have you ever been floating in a swimming pool,

你曾在游泳池裡飄浮嗎？

all comfy and warm, thinking,

那麼舒適與溫暖，常令人不禁遐想

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

「天啦，若能當太空人就太酷了！

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

你可以在外太空漂浮

俯瞰地球的一切

It'd be so neat!"

真是帥呆了！」

但事實並非如此

Only that's not how it is at all.

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

如果你到了外太空

你將會繞著地球旋轉

就是所謂的自由落體

it's called free fall.

You're actually falling towards the Earth.

事實上，你是朝著地面落下

好吧，仔細思考一下

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

你會感覺像這樣

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

就像你坐在即將爬到 最高點的雲霄飛車

「衝啊！哇！哇……！」

Only you're doing this

只是這回你將一直這樣下去

the whole time you're orbiting the Earth,

你就會繞著地球轉

二個

for two, three, four hours, days.

三個

四個

好幾個小時

Whatever it takes, right?

甚至好幾天

要幾天就幾天，對吧？

So, how does orbiting work?

那麼，為甚麼會繞行地球呢？

Let's take a page from Isaac Newton.

有請牛頓先生出場

He had this idea, a little mental experiment:

他想法是這樣的

這是一個小小的思想實驗

You take a cannon,

你將一門大砲

you put it on top of a hill.

放在一個小山頂上

如果你發射砲彈

If you shoot the cannonball,

it goes a little bit away.

飛到不遠處就落地了

But if you shoot it harder,

但是如果你射得更強一點

砲彈落地前會飛較長的距離

it goes far enough so that it lands

a little bit past the curvature of Earth.

落在地表曲面的較遠處

那麼， 想像一下

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

如果你把炮彈很快、很快的射出去

it would go all the way around the Earth

它會一路繞著地球走

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

最後繞回來，咚！

比如說，打到你後背或命中啥的

讓我們把焦點拉回太空

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

並把你放進

over the North Pole of the Earth

位於北極上空的人造衛星中

and consider north to be up.

並設北方為向上方向

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

結果你會落下，彷彿會撞上地球

但實際上你是快速向一旁移動

But you are actually moving sideways really fast.

So when you fall down,

所以，當你落下時

你會與地球擦身而過

you're going to miss.

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

最終你移動到地球的一邊

你持續往下落

and now the Earth is pulling you back in sideways.

地球把你往另一邊（地球）拉

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

於是，它把你拉回來

你再繼續落下

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

你也再度與地球擦身而過

現在，你在地球的下方

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

地球要把你往上拉

但你依然向側邊移動

所以你還是與地球無緣

So you're going to miss the Earth again.

現在，你在地球的另一邊了

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

向上移動的同時，地球把你向一旁拉

and the Earth's pulling you sideways.

於是，你持續往一邊偏

So you're going to fall sideways,

但是，因正在向上移動 所以你再次與地球擦身而過

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

你終於再次回到地球上方

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

在北極上空

going sideways and falling down,

持續往側邊移動並且往地球落下

and yep -- you guessed it.

沒錯，正如你所預測的

因為你一直飛快地移動 所以你將一直與地球擦身而過

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

In this way, astronauts orbit the Earth.

太空人就是以這種方式繞著地球轉

They're always falling towards the Earth,

他們持續朝地球落下

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

但始終錯過地球

因此，他們一直在下落

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

他們也感覺自己正在下落

所以多少都會習慣這種感覺

So technically, if you ran fast enough and tripped,

在技術上來說，如果你跑得夠快 突然被絆一腳而跳起來

you could miss the Earth.

你就可能對地球說再見了

但這裡面藏著一個大問題

But there's a big problem.

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

首先，你必須每秒狂奔 8 公里

That's 18,000 miles an hour,

相當於每小時 18,000 英里

just over Mach 23!

或超過 23 倍音速！

The second problem:

其次是

如果你真的跑那麼快

If you're going that fast,

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

雖然你可以繞著地球轉

並且回到起點

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

但是一路上會有大量的空氣等著你

much less people and things.

更不用說還有人和其他東西

So you would burn up due to atmospheric friction.

但你也將因摩擦生熱而燃燒殆盡

So, I do not recommend this.

所以我不建議這樣做