Cosmic Hysteresis

Abstract

Cosmological hysteresis, has interesting and vivid implications in the scenario of a cyclic bouncy universe. This, purely thermodynamical in nature, is caused by the asymmetry in the equation of state parameter during expansion and contraction phase of the universe, due to the presence of a single scalar field. When applied to variants of modified gravity models this phenomenon leads to the increase in amplitude of the consecutive cycles of the universe, provided we have physical mechanisms to make the universe bounce and turnaround. This also shows that the conditions which creates a universe with an ever increasing expansion, depend on the signature of $\oint pdV$ and on model parameters.

Comments: 6 pages, 3 figures, To appear in the Proceedings of the Fourteenth Marcel Grossman Meeting on General Relativity at University of Rome "La Sapienza" - Rome, July 12-18, 2015