2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/196931We show that in order to avoid a breakdown of general covariance at the quantum level the total flux in each outgoing partial wave of a quantum field in a black hole background must be equal to that of a (1+1)-dimensional blackbody at the Hawking temperature.5 pages, 1 figure; v2: typo corrected, reference added; v3: comment added, minor editorial changes to agree with published versionGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext