Photon Could Have the Rest Mass

From ancient, physics was named the science of measurement. The measurement in photoelectric effect proved that the light must be consisted of particles and the reason for the refusal of that was the double-slit experiment. In the double-slit experiment, we could observe interference fringes that justify the light as a wave. But we know that the constant mass of the electron was proven and have interference fringes in the double-slit experiment too. Therefore, there is at least one example with constant rest mass which has interference fringes in double-slit experiment. So, the removal of constant rest mass, for photon, is not a good solution to answer the observance of interference fringes in double-slit experiment. In this paper, we explain four real examples in different branches of physics based on a new theory, Saleh Theory, which known a photon as a small particle with constant rest mass. The compare was shown to determination of a violation in the Conservation of mass and energy principle. This indicates that where the photon rest mass is zero the mass and energy principle is violated and demonstrate that we need to use a new theory to improve all physics’ branches which encounter with photons.