Isotropic evolution of a JBD anisotropic Bianchi universe (Q5959865)

The author considers the space homogeneous cosmological model of Bianchi type VII in the framework of the Jordan-Brans-Dicke scalar-tensor theory of gravity, where an additional massless scalar field is introduced. It is assumed that this long range field is generated by the whole of matter in the Universe according to Mach's principle. The exact vacuum solutions of the field equations are obtained and their behaviour near the initial and final singularities is analyzed. It is shown that the spacelike 3-surfaces which are orbits of the isometry group can collapse to a 2-surface, to a string-like curve or to a point. Moreover, contrary to the prediction of General Relativity, this class of cosmological models evolves to the isotropic Friedman-Robertson-Walker universe in spite of initial anisotropic perturbation. The initial and final states of the model depend on the value of the coupling parameter.