I don't know why it's impossible, but, even for a moment, if you did assume that it's impossible -- I have a quotation from Sir Arthur C. Clarke, the science fiction writer whom I met in Colombo, and he said something which completely solves this problem.
我不知道为什么不可能，但是， 即使你认为这不可能 -- 我想引用Sir Arthur C. Clarke的一句话， 他是我在斯里兰卡首都科伦坡遇到的一位科幻小说作家， 他的这句话回答了这个问题。