来自《耶鲁大学开放课程：基础物理第1集第1集》

this p is what we call momentum,

我们用字母p表示动量
and its mass by this relation.

动量和质量之间有这样的关系
It's a particle of mass m and momentum p

一个质量为m 动量为p的粒子
has this energy so you solve for the energy,

有这么大的能量你解出能量
you get two answers.

得到两个解
Now, your temptation is to keep the first answer

你肯定想保留正根
because you know energy is not going to be negative.

因为你知道能量不会是负值
Particle's moving, it's got some energy and that's it.

粒子运动获得能量就是这样
But the mathematicians told Dirac,

但数学家们告诉狄拉克
"You cannot ignore the negative energy solution

你不能忽略负的能量
because it tells you there's a second solution

因为数学告诉我有两个根
and you cannot throw them out."

你不能随便丢掉