来自《耶鲁大学开放课程：基础物理 第14集 第14集》

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  Because the fastest signal is the light signal,
  因为最快的信号是光
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  and that won't get there.
  而光也到不了那里
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  And neither will anything else. Alright.
  所以其它东西也到不了
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  Now, we're going to do something
  现在我们要做一些
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  which is theoretically or mathematically very pretty.
  漂亮的理论或者说数学计算
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  So, for those of you who like mathematical elegance,
  对数学的优雅情有独钟的同学
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  this is certainly the best example I can offer you,
  这将是我能给你们举出的最好的例子
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  because it is simple and also rather profound.
  因为它简洁同时又内涵丰富
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  But it's completely by analogy.
  但它完全是通过类比得到的
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  The analogy is the following.
  类比是这样的
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  We have seen that
  我们已经知道
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  when we rotate our axis,
  当我们像我这样