The quantum effective action is computed at finite temperatures in a Robertson-Walker type of metric suggested in Kaluza-Klein theories. The most interesting result is that above a critical temperature the effective gravitational constant becomes negative if the extra dimension is large enough. This provides a mechanism for the bounce from a contracting phase and may explain how the extra space has decoupled from the general expansion. The bounce mechanism also leads to a picture of the recycling universe, in which entropy produced after many cycles of expansion and contraction may solve the horizon and the flatness problem of the standard cosmology.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)