2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/51084We discuss the possibility of a transition from a contracting flat space - big crunch - to an expanding flat space - big bang.12 pages, Talk given at the Francqui Colloquium, 2001, ``Strings and Gravity: Tying the Forces Together.''High Energy Physics - Theorytext