Metric gravity theories and cosmology. I. Physical interpretation and viability
Abstract
We critically review some concepts underlying current applications of gravity theories with Lagrangians depending on the full Riemann tensor to cosmology. We argue that it is impossible to reconstruct the underlying Lagrangian from the observational data: the Robertson-Walker spacetime is so simple and "flexible" that any cosmic evolution may be fitted by infinite number of Lagrangians. Confrontation of a solution with the astronomical data is obstructed by the existence of many frames of dynamical variables and the fact that initial data for the gravitational triplet depend on which frame is minimally coupled to ordinary matter. Prior to any application it is necessary to establish physical contents and viability of a given gravity theory.
Keywords
Cite
@article{arxiv.gr-qc/0702097,
title = {Metric gravity theories and cosmology. I. Physical interpretation and viability},
author = {Leszek M. Sokolowski},
journal= {arXiv preprint arXiv:gr-qc/0702097},
year = {2010}
}
Comments
29 pages. The previous version is divided in two separate papers. The first four chapters, expanded and modified, form the present paper. The title and abstract are adequately modified, some recent references added. The main conclusions remain unchanged. The second part will also appear in Class. Qu. Grav