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Listen to part of a lecture in a structural engineering class.
聽一段結構工程學課程。
Today let's begin to look at structural engineering in the Space Age.
今天我們開始講太空時代的結構工程學。
Uh, new problems...new possibilities mean we can think in new ways, find radically different approaches.
新的問題......新的可能性代表著我們也能從新的角度思考，找出完全不同的方法。
So let's consider...uh, well, what would you say is the biggest obstacle today to putting structures, equipment, people ...uh, anything really, into space?
想想......你覺得今天來說，要把結構、設備、人......任何東西吧，送入太空，最大的障礙是什么？
Well, the cost, right?
成本吧？
Exactly. I mean, just taking the space shuttle up and back one time is hugely expensive. Uh, why?
完全正確。我的意思是，僅僅是把太空船送出去再回來一次就已經是極度昂貴的了。為什么呢？
I guess a lot of it is for fuel, right? To...to get the rocket going fast enough.
我猜大部分（錢）花在燃料上，對吧？因為火箭的速度要足夠快。
OK. Fast enough to...
好。足夠快以......
To escape Earth's gravity.
以掙脫地球引力。
Good. So we are burning up an enormous amount of fuel at every launch just to get the rocket up to what's known as escape velocity.
對。我們每次發射都會燃燒掉大量的燃料，來讓火箭達到所謂的“逃逸速度”。
Now, escape velocity is around 11 kilometers a second, pretty fast. But do we really have to go this fast?
逃逸速度大約在每秒11公里，這非常快。但，我們真的需要這么快嗎？
Well, yeah. I mean, how else can you, um...escape?
要吧。我是指，要不然你怎么能......逃出去呢？
I mean, that's the whole point of escape velocity, right?
這是逃逸速度的全部意義所在，不是嗎？
Otherwise gravity will pull you back down to the Earth.
否則引力會把你拉回地球。
Actually, that's a common misconception.
事實上這是普遍的誤解。
Escape velocity is simply the speed of an object that's ...uh, let's say, shot out of a cannon, the minimum initial speed so that the object could later escape Earth's gravity on its own.
逃逸速度就是某物體的速度......這么說吧，某物體從大炮中發射出來所具有的最小初速度，這速度能讓該物體之后自行掙脫地球引力。
But that's just if there's no additional force being applied.
但這種情況是沒有額外外力的情況。
If you keep on supplying force to the object, keep on pushing it upward, it could pull away from Earth's gravity at any speed.
如果你持續給該物體提供動力，不斷把它往前推，任何速度下它都能擺脫地球引力。
Even really slow?
哪怕它很慢？
So you're saying ...like, if you had a ladder tall enough, you could just climb into space?
你說的是......如果你有一個足夠高的梯子，你能直接爬進太空？
Yeah! Uh, well, theoretically.
對。理論上來說。
I mean, I can see some practical problems with the ladder example.
我是指，我能想出梯子這個例子中一些實際應用中的問題。
Uh, like you might get just a little bit tired out after the first few thousand kilometers or so, uh, especially with all the oxygen tanks you'll have to be hauling up with you.
比如，在爬完剛開始的幾千公里后，你可能會覺得有點累，特別是你還要帶一大堆氧氣罐一起爬上去。
No. I was thinking more along the lines of an elevator.
我的想法更偏向于電梯那方面。
Wait! You are serious?
等等！你是認真的？
Sure. An elevator. That's a new idea to most of us, but in fact it's been around for over a century.
當然，電梯。這對我們來說是個新奇的想法，但事實上這種想法已經存在超過一百年了。
