Year: 2001
Type: article
Abstract: We consider a cosmological setting for which the currently expanding era is preceded by a contracting phase; that is, we assume the Universe experienced at least one bounce. We show that scalar hydrodynamic perturbations lead to a singular behavior of the Bardeen potential and/or its derivatives (i.e., the curvature) for whatever universe model for which the last bounce epoch can be smoothly and causally joined to the radiation dominated era. Such a universe would be filled with nonlinear perturbations long before nucleosynthesis, and would thus be incompatible with observations. We therefore conclude that no observable bounce could possibly have taken place in the early Universe if Einstein gravity together with hydrodynamical fluids is to describe its evolution, and hence, under these conditions, that the Universe has always expanded.
Authors: Patrick Peter, Nelson Pinto-Neto
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2056461828