2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/207070The effect of bulk viscisity on the evolution of the homogeneous and isotropic cosmological models is considered. Solutions are found, with a barotropic equation of state, and a viscosity coefficient that is proportional to a power of the energy density of the universe. For flat space, power law expansions, related to extended inflation are found as well as exponential solutions, related to old inflation; also a solution with expansion that is an exponential of an exponential of the time is found.8 pages, latex, no figuresGeneral Relativity and Quantum Cosmologytext