Cyclic multiverses

Abstract

Using the idea of regularisation of singularities due to the variability of the fundamental constants in cosmology we study the cyclic universe models. We find two models of oscillating and non-singular mass density and pressure ("non-singular" bounce) regularised by varying gravitational constant $G$ despite the scale factor evolution is oscillating and having sharp turning points ("singular" bounce). Both violating (big-bang) and non-violating (phantom) null energy condition models appear. Then, we extend this idea onto the multiverse containing cyclic individual universes with either growing or decreasing entropy though leaving the net entropy constant. In order to get an insight into the key idea, we consider the doubleverse with the same geometrical evolution of the two "parallel" universes with their physical evolution (physical coupling constants $c(t)$ and $G(t)$) being different. An interesting point is that there is a possibility to exchange the universes at the point of maximum expansion -- the fact which was already noticed in quantum cosmology. Similar scenario is also possible within the framework of Brans-Dicke theory where varying $G(t)$ is replaced by the dynamical Brans-Dicke field $\varphi (t)$ though these theories are slightly different.

12 pages, 7 figures, MNRAS style, revised, matches published version

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Cited by in corpus (8)

• Inter-universal entanglement in a cyclic multiverse
• Quantum cosmology of a conformal multiverse
• Spinor wave function of the Universe in non-minimally coupled varying constants cosmologies
• Sudden Future Singularities in Quintessence and Scalar-Tensor Quintessence Models
• Doubleverse entanglement in third quantized non-minimally coupled varying constants cosmologies
• Strength of singularities in varying constants theories
• Cosmological solutions with time-delay
• Decaying universes and the emergence of Bell-type interuniversal entanglement in varying fundamental constants cosmological model