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 unive rses, that bound is not satisfied. Furthermore, we found that the Fischler- Susskind bound is not compatible with a generalized second law of thermodyn amics in (2 + 1)-dimensional cosmology, neither the classical nor the quant um version. On the other hand, the Hubble entropy bound has been constructe d in (2 + 1)-dimensional cosmology and it is shown compatible with the gene ralized second law of thermodynamics. (C) 2000 Published by Elsevier Scienc e B.V. All rights reserved.