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Title: Classically Stable Nonsingular Cosmological Bounces

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 117; Journal Issue: 12; Related Information: CHORUS Timestamp: 2016-09-16 18:08:45; Journal ID: ISSN 0031-9007
American Physical Society
Country of Publication:
United States

Citation Formats

Ijjas, Anna, and Steinhardt, Paul J. Classically Stable Nonsingular Cosmological Bounces. United States: N. p., 2016. Web. doi:10.1103/PhysRevLett.117.121304.
Ijjas, Anna, & Steinhardt, Paul J. Classically Stable Nonsingular Cosmological Bounces. United States. doi:10.1103/PhysRevLett.117.121304.
Ijjas, Anna, and Steinhardt, Paul J. 2016. "Classically Stable Nonsingular Cosmological Bounces". United States. doi:10.1103/PhysRevLett.117.121304.
title = {Classically Stable Nonsingular Cosmological Bounces},
author = {Ijjas, Anna and Steinhardt, Paul J.},
abstractNote = {},
doi = {10.1103/PhysRevLett.117.121304},
journal = {Physical Review Letters},
number = 12,
volume = 117,
place = {United States},
year = 2016,
month = 9

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevLett.117.121304

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Cited by: 13works
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  • A new model is studied which describes the quantum behavior of transitions through an isotropic quantum cosmological bounce in loop quantum cosmology sourced by a free and massless scalar field. As an exactly solvable model even at the quantum level, it illustrates properties of dynamical coherent states and provides the basis for a systematic perturbation theory of loop quantum gravity. The detailed analysis is remarkably different from what is known for harmonic oscillator coherent states. Results are evaluated with regard to their implications in cosmology, including a demonstration that in general quantum fluctuations before and after the bounce are unrelated.more » Thus, even within this solvable model the condition of classicality at late times does not imply classicality at early times before the bounce without further assumptions. Nevertheless, the quantum state does evolve deterministically through the bounce.« less
  • An exactly solvable bounce model in loop quantum cosmology is identified which serves as a perturbative basis for realistic bounce scenarios. Its bouncing solutions are derived analytically, demonstrating why recent numerical simulations robustly led to smooth bounces under the assumption of semiclassicality. Several effects, easily included in a perturbative analysis, can however change this smoothness. The effective theory is not only applicable to such situations where numerical techniques become highly involved but also allows one to discuss conceptual issues. For instance, consequences of the notoriously difficult physical inner product can be implemented at the effective level. This indicates that evenmore » physical predictions from full quantum gravity can be obtained from perturbative effective equations.« less
  • The present work analyzes the various conditions in which there can be a bouncing universe solution in f(R) gravity. In the article an interesting method, to analyze the bouncing FRW solutions in a spatially flat universe using f(R) gravity models using an effective Einstein frame description of the process, is presented. The analysis shows that a cosmological bounce in the f(R) theory need not be described by an equivalent bounce in the Einstein frame description of the process where actually there may be no bounce at all. Nevertheless the Einstein frame description of the bouncing phenomena turns out to bemore » immensely important as the dynamics of the bounce becomes amenable to logic based on general relativistic intuition. The theory of scalar cosmological perturbations in the bouncing universe models in f(R) theories has also been worked out in the Einstein frame.« less
  • Some cosmological consequences of the superfluid vacuum state developed previously are discussed, particularly with regard to the initial stages of the universe. The transition temperature of the hadronic superfluid (superfluid during the hadron era) is estimated to be 10/sup 13/ K, which is the same as the Hagedorn temperature, giving a physical basis of the thermodynamic bootstrap model.