2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/181843We review astrophysical, cosmological and terrestrial evidence for and against the constancy of fundamental parameters of particle physics, and discuss theoretical issues of unification and scalar-mediated forces, finding that the current rate of variation is bounded by limits on violations of the weak equivalence principle.Space limited to 4 pages, AIP 6x9 inch format. To appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 2006High Energy Physics - PhenomenologyAstrophysicsGeneral Relativity and Quantum Cosmologytext