2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/36638We comment on two issues in quantum cosmology, in the context of the Wheeler-De Witt equation and wave function of the Universe: (i) arrow of time and interpretation of the wave function in the classically allowed regions; (ii) stability of an approximation of the Born-Oppenheimer type in classically forbidden regions of the scale factor.Lecture at NATO ASI "Structure Formation in the Universe", Cambridge, 26 July - 6 August, 1999General Relativity and Quantum Cosmologytext