Averaging procedure in variable G cosmologies
Abstract
Previous work in the literature had built a formalism for spatially averaged equations for the scale factor, giving rise to an averaged Raychaudhuri equation and averaged Hamiltonian constraint, which involve a backreaction source term. The present paper extends these equations to include models with variable Newton parameter and variable cosmological term, motivated by the nonperturbative renormalization program for quantum gravity based upon the EinsteinHilbert action. We focus on the BransDicke form of the renormalizationgroup improved action functional. The coupling between backreaction and spatially averaged threedimensional scalar curvature is found to survive, and a variable G cosmic quintet is found to emerge. Interestingly, under suitable assumptions, an approximate solution can be found where the early universe tends to a FriedmannLemaitreRobertsonWalker model, while keeping track of the original inhomogeneities through three effective fluids. The resulting qualitative picture is that of a universe consisting of baryons only, while inhomogeneities average out to give rise to the full darkside phenomenology.
 Publication:

General Relativity and Gravitation
 Pub Date:
 February 2010
 DOI:
 10.1007/s1071400908346
 arXiv:
 arXiv:0805.1203
 Bibcode:
 2010GReGr..42..241C
 Keywords:

 Spatial averages;
 BransDicke;
 ADM formalism;
 Renormalization group;
 General Relativity and Quantum Cosmology;
 Astrophysics
 EPrint:
 20 pages. In the new version, all original calculations have been improved, and the presentation has been further improved as well