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.
Inflationary spacetimes are not past-complete
12 Pith papers cite this work. Polarity classification is still indexing.
12
Pith papers citing it
abstract
Many inflating spacetimes are likely to violate the weak energy condition, a key assumption of singularity theorems. Here we offer a simple kinematical argument, requiring no energy condition, that a cosmological model which is inflating -- or just expanding sufficiently fast -- must be incomplete in null and timelike past directions. Specifically, we obtain a bound on the integral of the Hubble parameter over a past-directed timelike or null geodesic. Thus inflationary models require physics other than inflation to describe the past boundary of the inflating region of spacetime.
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A no-go theorem proves flat and open FRW universes cannot be nonsingular, geodesically complete and ANEC-consistent while closed universes can, with positive curvature mimicking phantom dark energy at the 1% level.
Wineglass wormholes, which can nucleate expanding baby universes, continuously connect to no-boundary instantons as their charge vanishes.
Constructs an explicit closed FRW curvature-supported bounce-inflation model with a canonical scalar field that remains geodesically complete, NEC-compliant, and yields standard slow-roll predictions.
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.
A stable initial state is identified in mLQC-I that diagonalizes the Hamiltonian and minimizes particle creation, with mode functions approximated analytically by Airy or cylindrical functions whose constants are fixed by that state.
Non-Bunch-Davies initial conditions substantially improve the fit of various single-field slow-roll inflation models to updated n_s-r constraints from ACT DR6 combined with Planck, DESI, and BICEP/Keck data.
Single-field inflation with ε(N) approaching a constant in (0,1) at early times forms an asymptotic universality class with a Weyl-flat null origin while producing ns and r values compatible with Planck data.
Semi-infinite slow contraction (ε>3) eliminates particle horizons, asymptotes to Minkowski in the past, remains geodesically complete and BGV-evading, and supplies stable low-entropy initial conditions after a non-singular bounce.
Simulations of accreting black holes in standard and complex spacetimes indicate that magnetic geometry, quantum corrections, and binary dynamics influence flares, precession, photon rings, and multi-wavelength variability, with potential EHT constraints.
Refines two-field DHOST bouncing model to match observed f_NL and keep strong-coupling scale above background energy, claiming full viability at linear and non-linear levels.
Lecture notes providing an advanced introduction to primordial inflation theory and perturbation theory in slow-roll and quasi-de Sitter spacetimes.
citing papers explorer
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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.
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Open case for a closed universe
A no-go theorem proves flat and open FRW universes cannot be nonsingular, geodesically complete and ANEC-consistent while closed universes can, with positive curvature mimicking phantom dark energy at the 1% level.
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Birth of Inflationary Universes via Wineglass Wormholes and their No-Boundary Relatives
Wineglass wormholes, which can nucleate expanding baby universes, continuously connect to no-boundary instantons as their charge vanishes.
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Geodesically Complete Curvature-Bounce Inflation
Constructs an explicit closed FRW curvature-supported bounce-inflation model with a canonical scalar field that remains geodesically complete, NEC-compliant, and yields standard slow-roll predictions.
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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.
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Stable initial conditions and analytical investigations of cosmological perturbations in a modified loop quantum cosmology
A stable initial state is identified in mLQC-I that diagonalizes the Hamiltonian and minimizes particle creation, with mode functions approximated analytically by Airy or cylindrical functions whose constants are fixed by that state.
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ACT-ing on inflation: Implications of non Bunch-Davies initial condition and reheating on single-field slow roll models
Non-Bunch-Davies initial conditions substantially improve the fit of various single-field slow-roll inflation models to updated n_s-r constraints from ACT DR6 combined with Planck, DESI, and BICEP/Keck data.
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Inflation from a Weyl-flat null origin
Single-field inflation with ε(N) approaching a constant in (0,1) at early times forms an asymptotic universality class with a Weyl-flat null origin while producing ns and r values compatible with Planck data.
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Causal Horizons, Geodesic Completeness and Stability in Slow Contraction Cosmology
Semi-infinite slow contraction (ε>3) eliminates particle horizons, asymptotes to Minkowski in the past, remains geodesically complete and BGV-evading, and supplies stable low-entropy initial conditions after a non-singular bounce.
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GRMHD and GRRT Simulations of Black Hole Accretion: Flares, Precession, and Complex Spacetimes
Simulations of accreting black holes in standard and complex spacetimes indicate that magnetic geometry, quantum corrections, and binary dynamics influence flares, precession, photon rings, and multi-wavelength variability, with potential EHT constraints.
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Non-Gaussianity and Strong-Coupling Problem in a Two-Field DHOST Bouncing Model
Refines two-field DHOST bouncing model to match observed f_NL and keep strong-coupling scale above background energy, claiming full viability at linear and non-linear levels.
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Three Advanced Lectures on Inflation
Lecture notes providing an advanced introduction to primordial inflation theory and perturbation theory in slow-roll and quasi-de Sitter spacetimes.