2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/87184The concept of Scwartzschild radius is extended to the photon and the upper limit imposed on the energy of a photon as a result of the three characteristics of the photon--the constancy of the velocity of light, the spin value of $1\hslash$ and the zero rest mass of the photon--is shown. Further the phase change that occurs to the photon at the Scwartzschild radius, from energy to matter as a result of vacuum fluctuations is indicated.General Physicstext