So, when the voltage difference between the plates is zero, or when we just don't have the plates there at all, the cathode rays are not bent, they just go right in a straight line, and they can be detected on this screen.

拐弯来测试它们是否带电,当两板之间电压为零，或者根本就,没有这两个板时，阴极射线是一条直线,它可以在屏幕上。

麻省理工公开课 - 化学原理课程节选

Let's call someting invisible not only it can't be seen, not only it can't be observed, but it can't be detected at all.

让我们把一些不仅是看不见的,不仅是观察不到的，而且是完全检测不到的，东西称为无形的。

耶鲁公开课 - 死亡课程节选