2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/51623We argue that $(0,1)$ heterotic string models with 4 non-heterotic spacetime dimensions may provide an instability of the vacuum to gravitational polarization in globally strong gravitational fields. This instability would be triggered during gravitational collapse by a non-local quantum switching process, and lead to the formation of regions of a high temperature broken symmetry phase which would be the equivalent in these string models of conventional black holes.17 pages, LaTeX 2e. v2 Corrected argument in section 2, typos fixedHigh Energy Physics - Theorytext