From the FAQ section of "why speed of photon changes in different medium". ------------- Moral of the story: the properties of a solid that we are familiar with have more to do with the "collective" behavior of a large number of atoms interacting with each other. In most cases, these do not reflect the properties of the individual, isolated atoms. ------------- If a photon can be emitted by an electron, an electron can also be hit by a photon. What happens if a photon hits an electron? Why do we have a double standard to explain the photon emission (we explain with just one atom with one electron), while to explain photon reflection we need the lattice? Another one: If a photon is originated from an electron, it has to start from speed zero. So, before it attains the speed c, there should be intermediate speeds, right?