Scalar-tensor cosmologies

A method is investigated which enables exact solutions to be found for vacuum and radiation-dominated Friedmann universes of all curvatures in scalar-tensor theories with an arbitrary form for the coupling, $\omega \left(\phi \right)$, of the scalar field which determines the strength of the gravitational field. Particular classes of solution are presented for specific representative choices of $\omega \left(\phi \right)$, including the theories of Brans and Dicke, Barker, and Bekenstein, to illustrate the range of cosmological behaviors that are possible.