Thermodynamics of nonsingular bouncing universes
  Homogeneous and isotropic, nonsingular, bouncing world models are designed to
evade the initial singularity at the beginning of the cosmic expansion. Here,
we study the thermodynamics of the subset of these models governed by general
relativity. Considering the entropy of matter, radiation and that the entropy
of the apparent horizon is proportional to its area, we argue that these models
do not respect the generalised second law of thermodynamics, also away from the
bounce.
