Consequently, we expect an energy footprint in the atom , because, considering the effect on the center of mass, the interaction, between a photon and an electron in an atom, affects both the energy level of the electron and the energy level of the center of mass of the atom. Here, we stress that this effect is well known in quantum physics , even if the approximation of neglecting it is usually accepted, because of the small energy contribution of the center of mass. The quantum state function, after this interaction, solution of the Schrödinger equation, can be obtained by the usual quantum mechanical approach . So, it was analytically shown that the macroscopic irreversibility is the consequence of the microscopic irreversibility due to the interaction photon-electron, or from a macroscopic point of view, between the electromagnetic waves and the matter.