« on: 14/02/2021 16:52:05 »
Photons have an inertial mass and a delayed gravitational mass. Gravitational perturbations travel at the speed of light. What we call massive particles cannot reach the speed of light. For a photon, its gravitational mass is totally redshifted in its direction of motion. That's why light bends twice as much as massive particles, because it has no massive counter field in its direction of motion.