Stability of Geodesically Complete Cosmologies
arXiv:1610.04207 · doi:10.1088/1475-7516/2016/11/047
Abstract
We study the stability of spatially flat FRW solutions which are geodesically complete, i.e. for which one can follow null (graviton) geodesics both in the past and in the future without ever encountering singularities. This is the case of NEC-violating cosmologies such as smooth bounces or solutions which approach Minkowski in the past. We study the EFT of linear perturbations around a solution of this kind, including the possibility of multiple fields and fluids. One generally faces a gradient instability which can be avoided only if the operator is present and its coefficient changes sign along the evolution. This operator (typical of beyond-Horndeski theories) does not lead to extra degrees of freedom, but cannot arise starting from any theory with second-order equations of motion. The change of sign of this operator prevents to set it to zero with a generalised disformal transformation.
18 pages, 2 figures. v2: minor changes; references added; version published in JCAP
References in corpus (9)
- The Effective Field Theory of Inflation
- Healthy theories beyond Horndeski
- Starting the Universe: Stable Violation of the Null Energy Condition and Non-standard Cosmologies
- Exploring gravitational theories beyond Horndeski
- Galilean Genesis: an alternative to inflation
- The Effective Theory of Quintessence: the w<-1 Side Unveiled
- Resilience of the standard predictions for primordial tensor modes
- Why the cosmological constant is small and positive
- Inflation from Minkowski Space
Cited by in corpus (49)
- Horndeski theory and beyond: a review
- The Effective Field Theory of nonsingular cosmology
- Primordial black holes from null energy condition violation during inflation
- Matter bounce cosmology with a generalized single field: non-Gaussianity and an extended no-go theorem
- Cuscuton gravity as a classically stable limiting curvature theory
- Pulsar timing array observations as possible hints for nonsingular cosmology
- Higher order derivative coupling to gravity and its cosmological implications
- Generating enhanced parity-violating gravitational waves during inflation with violation of the null energy condition
- Null energy condition violation during inflation and pulsar timing array observations
- Nanohertz gravitational waves from NEC violation in the early universe
- Generating enhanced primordial GWs during inflation with intermittent violation of NEC and diminishment of GW propagating speed
- Bouncing cosmology in extended gravity and its reconstruction as dark energy model
- Implication of GW170817 for cosmological bounces
- Probing the primordial universe with gravitational waves detectors
- Scale-invariant perturbations from NEC violation: A new variant of Galilean Genesis
- More on the first-order thermodynamics of scalar-tensor and Horndeski gravity
- Perturbative unitarity and NEC violation in genesis cosmology
- Parity-violation in bouncing cosmology
- Peculiar thermal states in the first-order thermodynamics of gravity
- Spinor driven cosmic bounces and their cosmological perturbations
- Explanatory Depth in Primordial Cosmology: A Comparative Study of Inflationary and Bouncing Paradigms
- Superluminality in DHOST theory with extra scalar
- A General Model for Dark Energy Crossing the Phantom Divide
- Soft theorems for boosts and other time symmetries
- Stable cosmological solutions in Horndeski theory
- Perturbations in generalized Galileon theories
- Superluminality in beyond Horndeski theory with extra scalar field
- Primordial non-Gaussianity from Galilean Genesis without strong coupling problem
- Stable non-singular cosmologies in beyond Horndeski theory and disformal transformations
- Numerical Relativity as a New Tool for Fundamental Cosmology
- Constraints on Inflation with Null Energy Condition Violation from Advanced LIGO and Advanced Virgo's First Three Observing Runs
- Eternal Universes
- Stable Singularity-free Cosmological Solutions in non-projectable Horava-Lifshitz Gravity
- Null energy condition violation and beyond Horndeski physics in light of DESI DR2 data
- Cuscuton Bounce Beyond the Linear Regime: Bispectrum and Strong Coupling Constraints
- Higher derivative SVT theories from Kaluza-Klein reductions of Horndeski theory
- Stability of nonsingular cosmologies in Galileon models with torsion. A no-go theorem for eternal subluminality
- Climbing over the potential barrier during inflation via null energy condition violation
- Can Horndeski Genesis be Nonpathological?
- Evolution of Generalized Brans-Dicke parameter within a Superbounce scenario
- Healthy Horndeski cosmologies with torsion
- How Much NEC Breaking Can the Universe Endure?
- Geodesic completeness, cosmological bounces and inflation
- Recent Developments in Degenerate Higher Order Scalar Tensor Theories
- A class of regular bouncing cosmologies
- Perturbations in Horndeski theory above anisotropic cosmological background
- Constraining matter-bounce scenario from scalar-induced vector perturbations
- Gravitational Waves from Primordial Black Holes formed by Null Energy Condition Violation during Inflation
- Geodesically Complete Curvature-Bounce Inflation