来自《耶鲁大学开放课程：基础物理 第17集 第17集》

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  Maybe it'll vanish for some negative infinity time,
  可能它会在某个负无穷的时间点消失
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  but I want this to be true at all times.
  但我想设它始终存在
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  The equation has to be obeyed at all times,
  这个等式必须始满足这个条件
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  so this guy certainly is not zero at all times,
  因此这一项始终不为零
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  so the only way to fix that is to have α^2+ω0^2=0.
  因此唯一只有令 α^2+ω0^2=0
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  That's the only solution, which is not a trivial solution.
  这是唯一的解 它不是个无效解
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  Well, that's a simple equation, right?
  那是个简单的等式不是吗
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  It's a quadratic equation that means α^2=-ω0^2,
  这个二次等式意味着 α^2=-ω0^2
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  or α=±i·ω0.
  或者说 α=±i·ω0
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  So, when we were young
  在我们小的时候
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  and we didn't know about complex numbers,
  不知道复数是什么时
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  we would come to this stage and we would quit and say,
  我们做到这一步时我们便会放弃并说