Explaining Why Light Slows in Glass

Abstract

BMJC Bieżanek

As I write, it is passing 111 years since Albert Einstein unwittingly explained why light slows in glass and yet today this is still thought to be a mystery. Once one knows the refractive index of a particular sample of glass from measurements of it, all of classical wave optics can be enumerated and explained. This is hypnotically convincing but what is not explained is why light appears to slow in glass in the first place, it just does that but we don’t know why. This ignorance is so unnecessary and so wanton that, once one does understand it, it becomes almost impossible to understand the mind-blindness of the most recent 111 years.

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