2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/117291We revisit the conjecture of a generalized second law of thermodynamics which states that the combined entropy of matter and horizons must grow. In an expanding universe a generalized second law restricts the equation of state. In particular, it conflicts with long phases of a phantom, w<-1, equation of state.8 pages, 4 figures, Contribution to the QUARKS 2006 conference in St. PetersburgAstrophysicstext