Cosmic Bounces and Cyclic Universes

Abstract

Cosmological models involving a bounce from a contracting to an expanding universe can address the standard cosmological puzzles and generate "primordial" density perturbations without the need for inflation. Some such models, in particular the ekpyrotic and cyclic models that we focus on, fit rather naturally into string theory. We discuss a number of topics related to these models: the reasoning that leads to the ekpyrotic phase, the predictions for upcoming observations, the differences between singular and non-singular models of the bounce as well as the predictive and explanatory power offered by these models.

28 pages. Contribution to the CQG focus issue on String Cosmology

References in corpus (26)

• Causality, Analyticity and an IR Obstruction to UV Completion
• Gravitational Wave Spectrum Induced by Primordial Scalar Perturbations
• Eternal inflation and its implications
• New Ekpyrotic Cosmology
• Galilean Genesis: an alternative to inflation
• Generating Ekpyrotic Curvature Perturbations Before the Big Bang
• Optimal limits on f_{NL}^{local} from WMAP 5-year data
• Non-Gaussianities in New Ekpyrotic Cosmology
• Non-Gaussianities from ekpyrotic collapse with multiple fields
• Making predictions in the multiverse
• Curvature perturbations from ekpyrotic collapse with multiple fields
• Colliding Branes in Heterotic M-theory
• Cosmic Bubble Collisions
• Dark Energy and the Return of the Phoenix Universe
• The New Ekpyrotic Ghost
• Cosmic Perturbations Through the Cyclic Ages
• Unstable growth of curvature perturbation in non-singular bouncing cosmologies
• Bouncing Negative-Tension Branes
• Effective Actions for Heterotic M-Theory
• A multitrace deformation of ABJM theory
• Dynamical Selection of the Primordial Density Fluctuation Amplitude
• Stringy corrections to a time-dependent background solution of string and M-Theory
• Holographic Space-time from the Big Bang to the de Sitter era
• Light-like Big Bang singularities in string and matrix theories
• Particle Production near an AdS Crunch
• Bouncing Cosmologies

Cited by in corpus (61)

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• Rescaled Einstein-Hilbert Gravity from $f(R)$ Gravity: Inflation, Dark Energy and the Swampland Criteria
• Accelerating Cosmology and Phase Structure of F(R) Gravity with Lagrange Multiplier Constraint: Mimetic Approach
• The bounce universe history from unimodular $F(R)$ gravity
• Non-Singular Bouncing Cosmology: Consistency of the Effective Description
• Higher-Derivative Chiral Superfield Actions Coupled to N=1 Supergravity
• Extended matter bounce scenario in ghost free $f(R,\mathcal{G})$ gravity compatible with GW170817
• Fingerprints of Primordial Universe Paradigms as Features in Density Perturbations
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• From a Bounce to the Dark Energy Era with $F(R)$ Gravity
• The Ghost Condensate in N=1 Supergravity
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• Superbounce and Loop Quantum Cosmology Ekpyrosis from Modified Gravity
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• Non-singular Bounce Cosmology from Lagrange Multiplier $F(R)$ Gravity
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• Cosmological Hysteresis and the Cyclic Universe
• Observational effects from quantum cosmology
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• Gauss-Bonnet modified gravity models with bouncing behavior
• Converting entropy to curvature perturbations after a cosmic bounce
• The Scale-invariant Power Spectrum of Primordial Curvature Perturbation in CSTB Cosmos
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• Quantum Transitions Through Cosmological Singularities
• DBI Inflation in N=1 Supergravity
• Loop Quantum Cosmology Corrected Gauss-Bonnet Singular Cosmology
• Supersymmetric Cubic Galileons Have Ghosts
• Generating cosmological perturbations in non-singular Horndeski cosmologies
• Parity violation in pre-inflationary bounce
• Diversity in the Phoenix Universe
• Spinor driven cosmic bounces and their cosmological perturbations
• Relativistic Wavepackets in Classically Chaotic Quantum Cosmological Billiards
• Conflation: a new type of accelerated expansion
• Viable non-singular cosmic bounce in holonomy improved F(R) gravity endowed with a Lagrange multiplier
• Fingerprints of a Non-Inflationary Universe from Massive Fields
• Canonical Scalar Field Inflation with a Woods-Saxon Potential
• Towards the bounce inflationary gravitational wave
• Viable Inflationary Evolution from Loop Quantum Cosmology Scalar-Tensor Theory
• Note on bouncing backgrounds
• Cuscuton Bounce Beyond the Linear Regime: Bispectrum and Strong Coupling Constraints
• Towards an Observational Appraisal of String Cosmology
• Type IV singular bouncing cosmology from $f(T)$ Gravity
• Notes on the post-bounce background dynamics in bouncing cosmologies
• Unifying an asymmetric bounce to the dark energy in Chern-Simons F(R) gravity
• Dirac equation for embedded 4-geometries