REVIEW 20 cited by
Null energy condition and superluminal propagation
Not yet reviewed by Pith; the record is open.
This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.
SPECIMEN: schema-true, not a live event
T0 review · schema-true
One-sentence machine reading of the paper's core claim.
pith:XXXXXXXX · record.json · timestamp
abstract
We study whether a violation of the null energy condition necessarily implies the presence of instabilities. We prove that this is the case in a large class of situations, including isotropic solids and fluids relevant for cosmology. On the other hand we present several counter-examples of consistent effective field theories possessing a stable background where the null energy condition is violated. Two necessary features of these counter-examples are the lack of isotropy of the background and the presence of superluminal modes. We argue that many of the properties of massive gravity can be understood by associating it to a solid at the edge of violating the null energy condition. We briefly analyze the difficulties of mimicking $\dot H>0$ in scalar tensor theories of gravity.
Forward citations
Cited by 20 Pith papers
-
Horndeski in motion
Shift-symmetric Horndeski scalars with a spatial gradient realize moving dark energy, with a universal momentum density T^0i = -Q lambda^i / sqrt(-g) and observable imprints on the CMB dipole and quadrupole.
-
Geodesic completeness of anisotropic cosmologies and the null energy condition
A Bianchi-I spacetime obeying the null energy condition and expanding in all directions at one time must have past-incomplete null geodesics.
-
Disentangling Similarity and Relatedness in Topic Models
Topic models lie on a spectrum from thematic-relatedness-rich to similarity-rich, and that position predicts which downstream tasks they handle well.
-
Schwinger-Keldysh effective theory of charge transport: redundancies and systematic $\omega/T$ expansion
Proves equivalence of redundant Goldstone and adjoint-matter formulations of SK EFTs for non-Abelian symmetries and extends both to all orders in ħω/T while classifying invariant kernels under DKMS and unitarity.
-
Cosmological Evidence for Dark Axion-Dark Baryon Interactions from Apparent Phantom Crossing
Dark axion–dark baryon interactions improve the fit to CMB+DESI+SNe by Δχ²=-14.5 over ΛCDM, via a non-monotonic dark-matter mass that mimics phantom crossing, while leaving the Hubble tension unresolved.
-
A solid unification of the dark sector
A generalized Chaplygin-type solid unifies dark matter and dark energy via an early pressureless phase transitioning to a late solid phase that supports acceleration and produces distinct low-redshift perturbation signatures.
-
Affine ANEC selects the closed FRW branch for geodesically complete cosmology
Affine ANEC obstructs non-static flat and open FRW from being null geodesically complete while ANEC-satisfying, but allows explicit scalar-field realizations for closed FRW with NEC-respecting matter.
-
Neutron Stars as Perfect Fluids: Extracting the Linearized Response Function
A covariant effective-field-theory derivation expresses a neutron star's quadrupolar tidal response as a sum over internal oscillation modes, with each mode's strength set by overlap and normalization integrals.
-
Quantum dynamics of perfect fluids
For Gaussian initial states, vortex modes contribute a finite, non-local stress response in a quantum perfect fluid, calculable without adding symmetry-breaking regulators.
-
Fully viable DHOST bounce with extra scalar
A constructed two-field DHOST bouncing cosmology that avoids ghost, gradient, and superluminality problems and produces nearly scale-invariant curvature perturbations.
-
Massive graviton dark matter searches with long-baseline atom interferometers
Long-baseline atom interferometers could detect ultra-light spin-2 dark matter through three coupling channels, reaching mass and coupling ranges that LIGO and LISA cannot cover.
-
On the Motion of Compact Objects in Relativistic Viscous Fluids
The authors derive covariant world-line effective field theory equations of motion for a compact object moving relativistically through a fluid, matching coefficients to potential and Stokes flow.
-
To bounce or not to bounce in generalized Proca theory and beyond
The authors claim generalized Proca theory cannot produce a stable non-singular bounce, but the proof relies on an incorrect derivative and a flawed sound-speed argument.
-
The Speed of Gravity
In the standard effective field theory of gravity, gravitational waves on cosmological backgrounds propagate at a speed differing from unity, and analyticity arguments favor superluminal speed relative to matter.
-
Geodesic completion of big bangs from emergent geometry
Phantom Chaplygin gas forces the Einstein-frame lapse to change sign smoothly while the causal-frame lapse stays positive, yielding a robust non-singular bounce even with extra matter.
-
Classical limit for Dirac fermions with modified action in the presence of the black hole
A covariant model of Dirac fermions with an extra Planck-derived term yields the same Einstein-equation collapse as ordinary GR yet permits numerical trajectories that escape the black hole.
-
Effective Field Theories for Material Media
Spacetime-symmetry-breaking Goldstone EFTs systematically describe bulk and localized excitations of solids, fluids, and superfluids, with new thermodynamic identifications and corrected scattering rates.
-
The energy conditions and model selection in the local Universe
Local HII galaxy and cosmic chronometer data favor the Rh=ct universe over ΛCDM at 92% vs 8% likelihood, with Rh=ct satisfying all energy conditions while ΛCDM violates the strong energy condition at z≲2.
-
Energy conditions of bouncing solutions in quadratic curvature gravity coupled with a scalar field
Bouncing solutions in quadratic curvature gravity with a scalar field satisfy null, weak, and dominant energy conditions but violate the strong one when using the scalar-field energy-momentum tensor, while all four co...
-
Effective Phantom Dark Energy: What Cosmological Reconstruction Does and Does Not Imply
Effective phantom dark energy is a background-level reconstruction that does not imply fundamental pathologies such as ghost instabilities or null energy condition violation by the underlying stress tensor.
Discussion (0). Continue with ORCID to comment.