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arXiv · 2011.05133

A classical, non-singular, bouncing universe

Özenç Güngör·Glenn D. Starkman
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Abstract

We present a model for a classical, non-singular bouncing cosmology without violation of the null energy condition (NEC). The field content is General Relativity plus a real scalar field with a canonical kinetic term and only renormalizable, polynomial type self-interaction for the scalar field in the Jordan frame. The universe begins vacuum-energy dominated and is contracting at $t=-\infty$. We consider a closed universe with a positive spatial curvature, which is responsible for the universe bouncing without any NEC violation. An $Rϕ^2$ coupling between the Ricci scalar and the scalar field drives the scalar from the initial false vacuum to the true vacuum during the bounce. The model is sub-Planckian throughout its evolution and every dimensionful parameter is below the effective field theory scale $M_P$, so we expect no ghost-type or tachyonic instabilities. This model solves the horizon problem and extends co-moving particle geodesics to past infinity, resulting in a geodesically complete universe without singularities. We solve the Friedman equations and the scalar field equation of motion numerically, and analytically under certain approximations.

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Özenç Güngör, Glenn D. Starkman. 2021-01-12. A classical, non-singular, bouncing universe. https://doi.org/10.1088/1475-7516%2F2021%2F04%2F003

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