来自《耶鲁大学开放课程：基础物理 第4集 第4集》

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  This is work as of 300 years ago.
  这就是 300 年前的成果
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  And no one's found anything wrong with Newton's Laws,
  只要不违背以下两个条件
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  provided you don't violate two conditions.
  就不会有人发现牛顿定律的错误
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  You don't deal with objects moving at speeds comparable to that of light,
  一是不研究接近光速运动的物体
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  and you don't deal with objects which are very, very tiny.
  二是不研究非常非常小的物体
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  The notion of what's very tiny will be very clear
  下学期你们学习量子力学时
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  when you learn quantum mechanics next term.
  就清楚什么是非常小的界定
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  Right now, there is something rough, called "Tiny, "
  现在就非常笼统地
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  there's things like atomic dimensions.
  把原子尺度的物体叫做 "很小"
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  So now we are going to do more concrete problems,
  现在我们要处理一些更为具体的问题
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  but I wanted to write that up for you as a simple, solvable,
  但我要为你们写得尽可能简单易算
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  worked-out example that displays everything that happens in physics.
  并能解释物理学中的许多问题