2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34327We argue that quantum theory in curved spacetime should be invariant under the continuous spacetime symmetries thaat are connected with the identity. For typical warped-product spacetimes, we prove that such invariance can be actually implemented, at least at the level of first quantization. Our approach rests on a mode decomposition which is special to the context of warped spacetimes.LaTeX, 26 pages, no figureGeneral Relativity and Quantum CosmologyMathematical Physicstext