2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/187775We demonstrate that in a vacuum-energy-dominated expansion phase, surprisingly neither the decay of matter nor matter-antimatter annihilation into relativistic particles can ever cause radiation to once again dominate over matter in the future history of the universe.updated version, as it will appear in Phys. Rev D. Title change, and some other minor alterationsAstrophysicsGeneral Relativity and Quantum CosmologyHigh Energy Physics - Phenomenologytext