Hello I was thinkng of this question and I found it best expressed in a clear manner in another site. I quote the question and waiting for an asnwer: "Is it a fundamental property of electrons that they can absorb photons? Geometry requires that two points define a straight line. Geometry does not prove this; it requires this. Does physics require that electrons can absorb photons, or can physics prove this. Can the system be explained in terms of the building blocks that combine to form electrons. A tank destroys buildings. To explain how, we must define what the tank does to the bricks and then define how this affects the entire building. Why do we assume that the reaction between an electron and a photon can be explained at the level of the entire electron. I want to know how does an electron absorb a photon at the level of the actual reaction; at the level of the bricks. Can we define the precise interaction between a photon and some part of an electron at the moment that they merge. Entropy and energy have no place here. Such terms are used to define the likelyhood of an event occuring; not in the mechanism? If we had a magical microscope through which we could view the process yet not affect the process, what would we see? A thoughtful answer deserves my most sincere thanks." Another question in the same realm how does a discharge electron give its kinetic energy to the atom colliding with it and excite it to an excited state similar to what happens in a fluorescent lamp?