Ekpyrotic and cyclic cosmology

By J. Lehners. 2008

337 citations recorded by the source corpus.

Abstract Ekpyrotic and cyclic cosmologies provide theories of the very early and of the very late universe. In these models, the big bang is described as a collision of branes — and thus the big bang is not the beginning of time. Before the big bang, there is an ekpyrotic phase with equation of state w = P ρ ≫ 1 (where P is the average pressure and ρ the average energy density) during which the universe slowly contracts. This phase resolves the standard cosmological puzzles and generates a nearly scale-invariant spectrum of cosmological perturbations containing a significant non-Gaussian component. At the same time it produces small-amplitude gravitational waves with a blue spectrum. The dark energy dominating the present-day cosmological evolution is reinterpreted as a small attractive force between our brane and a parallel one. This force eventually induces a new ekpyrotic phase and a new brane collision, leading to the idea of a cyclic universe. This review discusses the detailed properties of these models, their embedding in M-theory and their viability, with an emphasis on open issues and observational signatures.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2243c8d49f005d17fe070dc06a25f49e80e50f13

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Citations in the corpus

Rapidly-Varying Speed of Sound, Scale Invariance and Non-Gaussian Signatures (2008, background): “See [11] for a review of the ekpyrotic/cyclic scenario.”
Robust forecasts on fundamental physics from the foreground-obscured, gravitationally-lensed CMB polarization (2015, background): “detected at the appropriate level — they will be able to test alternatives to inflation such as the ekpyrotic model [93] and some models of loop quantum cosmology [94] at the 10sigma level, as well as beginning to distinguish between standard slow-roll inflation and more general single-field models ”
Exploring bouncing cosmologies with cosmological surveys (2014, background): “We refer to [75, 76] for recent reviews of various bouncing cosmologies.”
Towards a nonsingular bouncing cosmology (2012, background): “g [2] for an in-depth overview) were proposed as alternatives to inflationary cosmology as an explanation for the origin of the observed structure in the Universe.”
SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) OBSERVATIONS: COSMOLOGICAL INTERPRETATION (2010, background): “…production of particles and non-linear reheating, called “preheating,” occur due to parametric resonances (Enqvist et al. 2005; Jokinen & Mazumdar 2006; Chambers & Rajantie 2008; Bond et al. 2009); models in which the universe contracts first and then bounces (see Lehners 2008, for a review).”