2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34495We derive formulae for the time variation of the gravitational ``constant'' and of the fine structure ``constant'' in various models with extra dimensions and analyze their consistency with the observational data.5 pages, LaTeX, to appear in the Proceedings of the Spanish Relativity Meeting ERE-2002 (Mao, Spain, September 22-24, 2002)General Relativity and Quantum Cosmologytext