1. Quasi-isotropic cycles and non-singular bounces in a Mixmaster cosmology
- Author
-
Marco Bruni and Chandrima Ganguly
- Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,media_common.quotation_subject ,gr-qc ,Chaotic ,FOS: Physical sciences ,General Physics and Astronomy ,General Relativity and Quantum Cosmology (gr-qc) ,01 natural sciences ,Cosmology ,General Relativity and Quantum Cosmology ,law.invention ,symbols.namesake ,law ,0103 physical sciences ,Einstein ,010306 general physics ,STFC ,Mathematical physics ,media_common ,Physics ,Spacetime ,RCUK ,Universe ,Nonlinear system ,Invertible matrix ,symbols ,astro-ph.CO ,ST/N000668/1 ,Mixmaster universe ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
A Bianchi IX Mixmaster spacetime is the most general spatially homogeneous solution of Einstein's equations and it can represent the space-averaged Universe. We introduce two novel mechanisms resulting in a Mixmaster Universe with non-singular bounces which are quasi-isotropic. A fluid with a non-linear equation of state allows non-singular bounces. Using negative anisotropic stresses successfully isotropises this Universe and mitigates the well known Mixmaster chaotic behaviour. Thus the Universe can be an eternal Mixmaster, going through an infinite series of different cycles separated by bounces, with a sizable fraction of cycles isotropic enough to be well approximated by a standard Friedmann-Lema\^itre-Robertson-Walker model from the radiation era onward., Comment: 5 pages, 4 figures
- Published
- 2019