Microcanonical entropy of a cosmological model

A microcanonical entropy for a closed Friedmann universe filled with conformal bosons is defined and analyzed. A conformally invariant theory provides a constant of motion in terms of which entropy is defined and evaluated in a quantum statistical approximation for the bosons; gravitational contributions are potentially stabilized by the thermal fluctuations associated with the microcanonical constraint. This model can also lead to significant spatial inhomogeneities which are not small. (Auth.)