Constraints on backreaction in dust universes
Abstract
Description
We study backreaction in dust universes using exact equations which do not rely on perturbation theory, concentrating on theoretical and observational constraints. In particular, we discuss the recent suggestion (in hep-th/0503117) that superhorizon perturbations could explain present-day accelerated expansion as a useful example which can be ruled out. We note that a backreaction explanation of late-time acceleration will have to involve spatial curvature and subhorizon perturbations.
15 pages, 1 figure. v2: The numbers in observational constraints corrected (no qualitative change), added discussion and references. v3: More references, clearer presentation, a new section on theoretical bounds. Conclusions stronger. v4: Published version. No major changes
15 pages, 1 figure. v2: The numbers in observational constraints corrected (no qualitative change), added discussion and references. v3: More references, clearer presentation, a new section on theoretical bounds. Conclusions stronger. v4: Published version. No major changes