Oscillating and static universes from a single barotropic fluid
Abstract
We consider cosmological solutions to general relativity with a single barotropic fluid, where the pressure is a general function of the density, p = f(ρ). We derive conditions for static and oscillating solutions and provide examples, extending earlier work to these simpler and more general singlefluid cosmologies. Generically we expect such solutions to suffer from instabilities, through effects such as quantum fluctuations or tunneling to zero size. We also find a classical instability (``nogo'' theorem) for oscillating solutions of a single barotropic perfect fluid due to a necessarily negative squared sound speed.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 December 2015
 DOI:
 10.1088/14757516/2015/12/015
 arXiv:
 arXiv:1509.08915
 Bibcode:
 2015JCAP...12..015K
 Keywords:

 High Energy Physics  Theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 5 pages