2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/55391Branes may be approximated semi-classically by solutions of supergravity theories with event and Cauchy horizons. I suggest that if one wishes to avoid singularities and to capture accurately some of the properties of branes then these classical spacetimes must be identified so as to render them periodic in time.Latex, 12 pages, no figuresHigh Energy Physics - Theorytext