1308.1019 (C. Wetterich)

Variable gravity Universe    [PDF]

C. Wetterich

For variable gravity models the strength of gravity, as measured by Newton's "constant" or the Planck mass, depends on the value of a scalar field, the cosmon. Within this framework we discuss two simple models with a quadratic or constant cosmon potential. They describe a realistic cosmological sequence of inflation, radiation- and matter-domination. Dark Energy constitutes a small, almost constant fraction of the energy density during the radiation and matter dominated epochs (Early Dark Energy). In the present epoch we witness a transition to a new Dark Energy dominated epoch. In our models the inflaton and the scalar field of quintessence are the same cosmon field. It is remarkable how simple models involving only one scalar field can be compatible with all presently available cosmological observations. Our models are free of a big bang singularity. The stability of solutions generates an arrow of time.

View original: http://arxiv.org/abs/1308.1019