And this is a very fast speed, of course, it's about 700 million miles per hour. So, one way to put that in perspective is to think about how long it takes for a light beam to get from earth to the moon. Does anyone have any guesses? Eight seconds, that sounds good.

当然这是一个非常快的速度，它大约是每小时7亿英里,为了更形象化，我们,看看光从地球到月球,需要多少时间，你们猜猜是多少？,8秒，猜的不错。

麻省理工公开课 - 化学原理课程节选

There is no way that you could irradiate a crystal of nickel with a single beam of x-rays and get that circular ring pattern if the electron beam were behaving as a particle beam only.

没有什么其他的途径,可以让镍晶体发射,单束X光来,继而得到环状图案,如果电子束,是以粒子束形式出现的。

麻省理工公开课 - 固态化学导论课程节选