Results 81 to 90 of about 52,296 (249)
Cosmology Due to Thermodynamics of Apparent Horizon
Annalen der Physik, EarlyView.Effective cosmological constant as a function of the Hubble rate H for different entropy parameters b. Figure shows the asymptotic of the effective cosmological constant. At H = 0 the effective cosmological constant vanishes. Abstract This study proposes new entropy of the apparent horizon Sh=(1/β)arctan(βSBH)$S_h=(1/\beta)\arctan (\beta S_{BH ...
S. I. Kruglov
wiley +1 more source
Quantum vacuum energy in general relativity [PDF]
, 2017 The paper deals with the scale discrepancy between the observed vacuum energy in cosmology and the theoretical quantum vacuum energy (cosmological constant problem).
C. Henke
semanticscholar +1 more source
Global and microlocal aspects of Dirac operators: Propagators and Hadamard states
Mathematische Nachrichten, EarlyView.Abstract We propose a geometric approach to construct the Cauchy evolution operator for the Lorentzian Dirac operator on Cauchy‐compact globally hyperbolic 4‐manifolds. We realize the Cauchy evolution operator as the sum of two invariantly defined oscillatory integrals—the positive and negative Dirac propagators—global in space and in time, with ...
Matteo Capoferri, Simone Murro
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Classical and quantum cosmology of K-essentially modified $$R^2$$ and pure $$R^p$$ gravity [PDF]
General Relativity and Gravitation, 2018 We present a gravitational action with a modified higher order term of a combination of scalar curvature and Lagrangian density of a scalar field. This type of models has been considered first by Cruz-Dombriz et al.
N. Kan, Kiyoshi Shiraishi, Mai Yashiki
semanticscholar +1 more source
Fortschritte der Physik, EarlyView.Abstract The unification of conformal and fuzzy gravities with internal interactions is based on the facts that i) the tangent group of a curved manifold and the manifold itself do not necessarily have the same dimensions and ii) both gravitational theories considered here have been formulated in a gauge theoretic way.
Gregory Patellis +3 more
wiley +1 more source
Anomaly-induced effective action and Chern–Simons modification of general relativity
Physics Letters B, 2015 Recently it was shown that the quantum vacuum effects of massless chiral fermion field in curved space–time leads to the parity-violating Pontryagin density term, which appears in the trace anomaly with imaginary coefficient.
Sebastião Mauro, Ilya L. Shapiro
doaj +1 more source
Bekenstein’s Entropy Bound-Particle Horizon Approach to Avoid the Cosmological Singularity
Entropy, 2020 The cosmological singularity of infinite density, temperature, and spacetime curvature is the classical limit of Friedmann’s general relativity solutions extrapolated to the origin of the standard model of cosmology.
James R. Powell +2 more
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Probing time orientability of spacetime
European Physical Journal C: Particles and Fields, 2023 In general relativity, cosmology and quantum field theory, spacetime is assumed to be an orientable manifold endowed with a Lorentz metric that makes it spatially and temporally orientable.
N. A. Lemos, D. Müller, M. J. Rebouças
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Non‐contrastive transcendence as gift and challenge to science and religion
Modern Theology, EarlyView.Abstract This article suggests that the nature of transcendence represents a promising topic for future engagement between revision‐minded theologians in the field of science and religion and tradition‐oriented ones. It does so by drawing on Kathryn Tanner's account of non‐contrastive transcendence within the history of Christian theology to illuminate
Peter N. Jordan
wiley +1 more source
The simplicity of physical laws
Noûs, EarlyView.Abstract Physical laws are strikingly simple, yet there is no a priori reason for them to be so. I propose that nomic realists—Humeans and non‐Humeans—should recognize simplicity as a fundamental epistemic guide for discovering and evaluating candidate physical laws.
Eddy Keming Chen
wiley +1 more source