来自《耶鲁大学开放课程：基础物理第6集第6集》

cannot just be U(1) - U(2)

不能只是 U(1) - U(2)
U(1) - U(2) says,

U(1) - U(2) 意思是
tell me what you ended, tell me where you start,

告诉我终点告诉我起点
and that difference of some function U

函数 U 在那两点的值的差
between those two points is the work done.

就是所做的功
In other words, I'm asking you to think critically

换句话说我希望你们认真地想一下
about whether this equality really could be true.

这个等式到底是不是对的
This is some function U in the xy plane

这是在 xy 坐标轴中的函数 U
evaluated at one point minus the other point.

在这一点和另一点赋值相减
This is on a path joining those two points

这是连接两点的路径
but I have not told you which path

但我不告诉你是哪一条
and I can draw any path I like with those same end points.

我可以画出任何连接这两点的路径