QUANTUM AND THERMAL EFFECTS IN THE MATTER-GRAVITY SYSTEM

The matter-gravity system is examined in a path integral approach for the case of conformal matter coupled to a Friedmann-Robertson-Walker s pace time. In particular the case of gravitational potentials of inter est in cosmology for which the universe tunnels from a small radius is examined. It is observed that in the presence of such gravitational h orizons the universe evolves in a complex time and it is shown how a c lassical time and temperature emerge. Correspondingly one will have co mpensating quantum and thermal fluctuations for the matter and gravity system and it is noted that the unstable mode of gravity correspondin g to the universe tunnelling into existence will be compensated by ana logous modes for matter corresponding to its creation.