EFFECTS OF ANISOTROPY AND SPATIAL CURVATURE ON THE PRE-BIG-BANG SCENARIO - ART. NO. 044017

A class of exact, anisotropic cosmological solutions to the vacuum Bra ns-Dicke theory of gravity is considered within the context of the pre -big-bang scenario. Included in this class are the Bianchi type III, V and VIh models and the spatially isotropic, negatively curved Friedma nn-Robertson-Walker universe. The effects of large anisotropy and spat ial curvature are determined. In contrast with a negatively curved Fri edmann-Robertson-Walker model, there exist regions of the parameter sp ace in which the combined effects of curvature and anisotropy prevent the occurrence of inflation. When inflation is possible, the necessary and sufficient conditions for successful pre-big-bang inflation are m ore stringent than in the isotropic models. The initial state for thes e models is established and corresponds in general to a gravitational plane wave. [S0556-2821(98)03316-5].