What is the QED explanation for specular reflection of light ? I mean, if photons interact with electrons, and a photon is re-emitted, I assume it can be emitted in any direction whatsoever. So this might work great for diffuse reflections. But what about specular reflections? How are they accounted for ? Also, what makes material different in terms of how well they do speculary reflect light ? For example why Hg makes such a great specular reflector ?