So here we have energy increasing on the y-axis, and you see this straight line at the bottom here is lower down on the graph, and that's the energy of a bound electron, so that's going to be a low stable energy.

这里我们看到能量沿着y轴增加，而且在这张图片上,这条直线在底部是降低的，那是一个束缚电子的能量，所以那是一个低稳态能量。

麻省理工公开课 - 化学原理课程节选

That's a choice, and that choice turns out to be very interesting and really important, because if you connect these two points together, you get a straight line that has to intercept the x-axis at some point.

在这一选择下,我们会发现一件非常有趣，而且极其重要的事,当你把这两点用直线连接起来，你会发现这条直线,将与x轴在某点相交。

麻省理工公开课 - 热力学与动力学课程节选