So, for example, when people, and we'll talk about this next class, were looking at different characteristics spectra of different atoms, what they were seeing is that it appeared to be these very discreet lines that were allowed or not allowed for the different atoms to emit, but they had no way to explain this using classical physics.

举个例子，当大家看到,不同原子的特征光谱时,他们看到的是一些分离的线,那可以使不同的原子,发射或不发射出去，但是这些无法用经典物理来解释。

麻省理工公开课 - 化学原理课程节选