He's talking about the difference between the visible and invisible things.

他谈到了有形和无形,的东西二者的区别。

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And you have to ask yourself is the energy difference here, the delta E in the electronic states, how does that compare with the E of visible light?

所以我们会问,是由于能量的不同么，例如deltaE在电子能态的不同，那如何把E与可见光联系起来？

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