2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/149064A unification model for strong, electromagnetic, weak and gravitational forces is proposed. The tangent space of ordinary coordinate 4-dimensional spacetime is a submanifold of an 14-dimensional internal spacetime spanned by four frame fields. The unification of the standard model with gravity is governed by gauge symmetry in the internal spacetime.9 pages, Revtex, no figures, minor changes, Published in: Science in China, Series A41 (1998) 324High Energy Physics - PhenomenologyGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext