English is not my native language. So, I hope to be understood. :-) The Compton effect is the dynamics in which high-energy incident photons (X or gamma) are scattered by electrons of certain materials, like graphite. The electrons are supposed to be free, as they are only weakly bounded by their atoms, especially considering the high energy of colliding photons. Well, the implications ot this effect are to me rather confusing. If I approach the problem, considering the conservation laws for energy and momentum, I have no difficulty in understanding the wavelenght variation wich affects the scattered photon. Of course, I have to consider the quadrivector in that calculation, since I deal with a relativistic process (photons are involved). Until here, no problem. But, when I try to interpret the effect I loose my mind. The conservation laws span over the ends of the timeframe between the arrival of the incident photon and the scattering of the photon. Anyhow, they don't tell me anything about what happens in that interval. I would like to know it, because I cannot assume that a single photon is directly deflected or bounced like a bowl, even if this is what appears in terms of ending outcome from our point of view. In the matter of fact, a photon is a quantum, so it should not interact partially, i.e. transfer only a certain amount of its energy. A quantum has instead to interact totally or not interact at all. This means, in my opinion, that the incident photon should be absorbed somewhere and that a second photon, with less energy, should be then emitted. I think so to a two-photons process. There is now a big problem: a free electron can't absorb or emit a photon. So, the photon, in the case, should interact elsewhere. Is then the atom involved? Does the atom (or the internal electrons) 'digest' the incident photon and then release to the free electron the amount of energy needed for the emission of a second photon? Where do I have a misconcept of the process? Thank you.