Holography and the generalized second law of thermodynamics in (2+1)-dimensional cosmology

The Fischler–Susskind entropy bound has been studied in (2+1)-dimensional universes with negative cosmological constant. As in all contracting universes, that bound is not satisfied. Furthermore, we found that the Fischler–Susskind bound is not compatible with a generalized second law of thermodynamics in (2+1)-dimensional cosmology, neither the classical nor the quantum version. On the other hand, the Hubble entropy bound has been constructed in (2+1)-dimensional cosmology and it is shown compatible with the generalized second law of thermodynamics.