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A classical, non-singular, bouncing universe
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DOI：10.1088/1475-7516/2021/04/003.png)
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Abstract
En 中文
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-interactions for the scalar field in the Jordan frame. The universe begins vacuum-energy dominated and is contracting at t = -infinity. We consider a closed universe with a positive spatial curvature, which is responsible for the universe bouncing without any NEC violation. An R phi(2) coupling between the Ricci scalar and the scalar field drives the scalar field 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.
Keywords:
alternatives to inflation
initial conditions and eternal universe
Journal
IF:
5.9
Papers:
1.3W
Citations:
4.7W