2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/102894In this brief note we comment on a recent attempt by Martineau and Brandenberger (astro-ph/0510523) to explain the acceleration of the Universe using the back-reaction of long-wavelength perturbations associated with isocurvature perturbation modes.7 pagesAstrophysicsGeneral Relativity and Quantum CosmologyHigh Energy Physics - PhenomenologyHigh Energy Physics - Theorytext