2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/35278We present an exact solution to the Einstein field equations which is Ricci and Riemann flat in five dimensions, but in four dimensions is a good model for the early vacuum-dominated universe.6 pages; to appear in Journal of Mathematical Physics; v2: reference 3 correctedGeneral Relativity and Quantum Cosmologytext