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Time-Dependent Warping and Non-Singular Bouncing Cosmologies
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In this article, a family of non-singular time-dependent solutions of a six-dimensional gravitational theory that are warped products of a four dimensional bouncing cosmological solution and a two dimensional internal manifold is constructed.Abstract:
In this note, we construct a family of non-singular time-dependent solutions of a six-dimensional gravitational theory that are warped products of a four dimensional bouncing cosmological solution and a two dimensional internal manifold. The warp factor is time-dependent and breaks translation invariance along one of the internal directions. When the warp factor is periodic in time, the non-compact part of the geometry bounces periodically. The six dimensional geometry is supported by matter that does not violate the null energy condition. We show that this 6D geometry does not admit a closed trapped surface and hence the Hawking-Penrose singularity theorems do not apply to these solutions. We also present examples of singular solutions where the topology of the internal manifold changes dynamically.read more
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Exploring eternal stability with the simple harmonic universe
TL;DR: In this paper, the authors construct nonsingular cyclic cosmologies that respect the null energy condition, have a large hierarchy between the minimum and maximum size of the universe, and are stable under linearized fluctuations and argue that Casimir energy contributions associated to the compact spatial slices can become important at short scales and may lift nonperturbative decays towards vanishing size.
Journal ArticleDOI
Exploring eternal stability with the simple harmonic universe
TL;DR: In this paper, the authors construct nonsingular cyclic cosmologies that respect the null energy condition, have a large hierarchy between the minimum and maximum size of the universe, and are stable under linearized fluctuations and argue that Casimir energy contributions associated to the compact spatial slices can become important at short scales and lift nonperturbative decays towards vanishing size.
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Dissertation
Exploring Warped Compactifications of Extra Dimensions
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