2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34113Static, spherically symmetric, traversable wormholes, induced by massless, nonminimally coupled scalar fields in general relativity, are shown to be unstable under spherically symmetric perturbations. The instability is related to blowing-up of the effective gravitational constant on a certain sphere.Latex2e, 4 pages. Minor corrections, a reference addedGeneral Relativity and Quantum Cosmologytext