Recycling the universe using scaler fields - art. no. 083520

We examine the behavior of a closed oscillating universe filled with a homo geneous scalar field and find that, contrary to naive expectations, such a universe expands to larger volumes during successive expansion epochs. This intriguing behavior introduces an arrow of time in a system which is time reversible. The increase in the maximum size of the universe is closely rel ated to the work done on or by the scalar field during one complete oscilla tory cycle which, in turn, is related to the asymmetry in the scalar field equation of state during expansion and collapse. Our analysis shows that sc alar fields with polynomial potentials V(phi) = lambda phi (q), q>1, lead t o a growing oscillation amplitude for the universe: the increase in amplitu de between successive oscillations is more significant for smaller values o f q. Such behavior allows for the effective recycling of the universe. A re cycled universe can be quite old and can resolve the flatness problem. Thes e results have strong bearing on cosmological models in which the role of d ark matter is played by a scalar field. They are also relevant for chaotic inflationary models of the early universe since they demonstrate that, even if the universe fails to inflate the first time around, it will eventually do so during future oscillatory cycles. Thus, the space of initial conditi ons favorable for chaotic inflation increases significantly.