Dynamical Systems Treatment of Scalar Field Cosmologies

Abstract

The conformal equivalence of some cosmological models in Brans-Dicke theory to general relativistic cosmologies with a scalar field is discussed. In the case of radiation-dominated universes, it is shown that the presence of the scalar field has a negligible impact upon the evolution of the models in the Einstein frame. It is also shown that power-law inflation in general relativity, which is conformal to ``extended'' power-law inflation in Brans-Dicke theory, is not a unique attractor for expanding closed universes, but rather that the occurence of inflation depends upon the initial kinetic energy of the scalar field.