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You know, all life developed here on Earth with gravity being present, so life evolved under the influence of gravity, and then we grow up with gravity being present, so we learn how to walk and catch a ball and ice skate or whatever, all with gravity being present.
你知道，地球上的生物在重力環境下生存，在重力影響下進化，在重力的前提下成長，所以我們學會如何走路、如何接球，以及溜冰等等，這些都與重力的存在息息相關。
And what if you were to grow up without gravity?
那么如果你不是在重力環境下長大的呢？
What about the systems that depend on gravity, like your muscles or your balance system or the heart and blood vessels?
那些依賴重力的身體系統，比如肌肉、平衡系統或者心血管系統會怎么樣呢？
Would they develop normally, or would they be different in some way?
它們會正常發展嗎？或者會有所不同嗎？
One reason why you might think that it would go down a different pathway is from an experiment that was done some time ago by two neuroscientists called Hubel and Wiesel.
你可能覺得事情會朝另一個方向發展，不久以前，兩個叫做休博爾和維瑟爾的神經學家做的實驗替你給出了理由。
And what they did is they had a kitten, and they put a patch over the eye of the kitten.
他們有一只小貓，他們給小貓的一只眼睛戴上眼罩。
And then the kitten grew up to be a cat, and they removed the patch.
小貓長大后，他們為其取下眼罩。
And so, the question is, can the cat see out of that eye?
那么，問題是它能用那只眼睛看到東西么？
Now, there's nothing wrong with the eye, right?
現在，眼睛本身沒有任何問題，對吧？
But it just hasn't seen anything, there hasn't been any light coming in.
但是貓看不到任何東西，這只眼睛感知不見任何光線。
And the answer is that the cat can't see out of that eye because what happens is that the brain goes down a different pathway when it develops and the connections that would ordinarily develop to that eye don't develop.
答案是，貓不能從那只眼睛看到任何東西，因為它在大腦發育上出了岔子，本應該發育的那只眼睛的連接沒有發育。
And that can't be undone, that's a permanent change.
而且這是不可逆的，是一個永久的改變。
So, the brain of that cat is fundamentally different from the brain of a cat that grew up seeing out of that eye.
所以，這只貓的大腦與通過那只眼睛視物長大的貓的大腦根本不一樣。
That cat grew up with a different brain, in essence.
本質上，那只貓長出了一顆不一樣的大腦。
So, then you wonder, well, what about gravity?
然后，你會奇怪，好吧，那么重力怎么說？
What if you don't have the forces that gravity produces?
失去重力的影響會怎么樣？
Is your balance organ going to develop in the same way, or will it be different?
你的平衡系統將會以同樣的方式來發育嗎？抑或是按另一種方式發育？
If somebody grew up in space, could they come back to Earth and function, or would they really be a different person?
如果有人在太空中長大，他們能回到地球上并且功能健全嗎？又或者他們實際上會變成一個不一樣的人？
