2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/36197We briefly recall the problem of defining conserved quantities such as energy in general relativity, and the solution by introducing a symmetric background. We apply the general formalism to perturbed Robertson-Walker spacetimes with de Sitter geometry as background. We relate the obtained conserved quantities to Traschen's integral constraints and mention a few applications in cosmology.7 pages, no figure, published in the Proceedings of the workshop on Cosmology and Time Asymmetry, Peyresq, July 21-31,1996, Int. Jour. Theor. Physics, 36, 2461 (1997)General Relativity and Quantum Cosmologytext