2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/111192The photon vacuum polarization effect in curved spacetime leads to birefringence, i.e. the photon velocity becomes greater than (or less than) the speed of light depending on its polarization. We investigate this phenomenon in a Schwarzschild curved spacetime.superluminal quantum modified photon propagationGeneral Relativity and Quantum Cosmologytext