2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/35361An exact energy expression for a physical black hole is derived by considering the escape of a photon from the black hole. The mass of the black hole within its horizon is found to be twice its mass as observed at infinity. This result is important in understanding gravitational waves in black hole collisions.General Relativity and Quantum CosmologyHigh Energy Physics - Theorytext