来自《耶鲁大学开放课程：基础物理 第1集 第1集》

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  One is the lowest dimension.
  维数最小只能是1
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  I cannot make the object simpler than being just a mathematical point.
  找不到比质点更简单的模型了
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  Then, you've got to say,
  然后 也许你会问
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  "What do I have to know about this object at the initial time?
  我需要知道物体初始状态的哪些信息呢
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  What constitutes the present,
  是什么构成了现在
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  or what constitutes maximal information about the present?"
  或者说 现在的全部信息是由哪些构成的
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  So what we do is we pick an origin, call it zero,
  我们现在选择一个原点 取该点值为零
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  we put some markers there to measure distance,
  我们做一些标记来测量距离
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  and we say this guy is sitting at 1,2,3,4,5.
  这个点在五个单位长度的地方
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  He is sitting at x = 5.
  这个点的坐标是x=5
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  Now, of course, we've got to have units
  当然 这里还得有单位
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  and the units for lengths are going to be meters.
  长度的单位是"米"