2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/51225The effect of the spontaneous nucleation of black holes in de Sitter space is reviewed, and the main steps of the calculation in Nucl.Phys. B 582, 313, 2000 of the one-loop amplitude of this process are summarized. The existence of such an effect suggests that de Sitter space is not a ground state of quantum gravity with a positive cosmological constant.13 pages. Talk given at the workshop ``Quantum Gravity and Strings'', Dubna, June 2001High Energy Physics - Theorytext