2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/186915We point out that spacetime singularities play a useful role in gravitational theories by eliminating unphysical solutions. In particular, we argue that any modification of general relativity which is completely nonsingular cannot have a stable ground state. This argument applies both to classical extensions of general relativity, and to candidate quantum theories of gravity.5 pages, no figures; a few clarifying comments addedGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext