Results 21 to 30 of about 613 (177)
Einstein and Rastall theories of gravitation in comparison
European Physical Journal C: Particles and Fields, 2018 We profit by a recent paper of Visser claiming that Rastall gravity is equivalent to Einstein gravity to compare the two gravitational theories in a general way. Our conclusions are different from Visser’s ones.
F. Darabi +4 more
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Does a Theory of Everything Exist?
Философия и космология, 2021 Since Einstein’s failure to define a Grand Unified Theory, physicists have pursued a comprehensive theory explaining nature, a Theory of Everything. But because General Relativity, Quantum Field Theory, and Cosmology have little in common, defining one ...
James R Johnson
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$$f(\mathcal {G})$$ f(G) Noether cosmology
European Physical Journal C: Particles and Fields, 2020 We develop the n-dimensional cosmology for $$f(\mathcal {G})$$ f(G) gravity, where $$\mathcal {G}$$ G is the Gauss–Bonnet topological invariant. Specifically, by the so-called Noether Symmetry Approach, we select $$f(\mathcal {G})\simeq \mathcal {G}^k ...
Francesco Bajardi, Salvatore Capozziello
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DeWitt boundary condition is consistent in Hořava-Lifshitz quantum gravity
Physics Letters B, 2022 In quantum cosmology the DeWitt boundary condition is a proposal to set the wave function of the universe to vanish at the classical big-bang singularity.
Hiroki Matsui +2 more
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Journal of High Energy Physics, 2020 It was recently shown that the homogeneous and isotropic cosmology of a massless scalar field coupled to general relativity exhibits a new hidden conformal invariance under Mobius transformation of the proper time, additionally to the invariance under ...
Jibril Ben Achour, Etera R. Livine
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Two-photon amplitude interferometry for precision astrometry
The Open Journal of Astrophysics, 2022 Improved quantum sensing of photons from astronomical objects could provide high resolution observations in the optical benefiting numerous fields, including general relativity, dark matter studies, and cosmology.
Paul Stankus +3 more
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Minisuperspace Quantum Cosmology in Metric and Affine Theories of Gravity
Universe, 2022 Minisuperspace Quantum Cosmology is an approach by which it is possible to infer initial conditions for dynamical systems which can suitably represent observable and non-observable universes. Here we discuss theories of gravity which, from various points
Salvatore Capozziello, Francesco Bajardi
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Analytical investigation of pre-inflationary effects in the primordial power spectrum: from General Relativity to hybrid Loop Quantum Cosmology [PDF]
Journal of Cosmology and Astroparticle Physics, 2021 This work is an analytical study of the main differences between classical inflationary effects of a fast-roll regime and imprints of hybrid Loop Quantum Cosmology (LQC) on the primordial power spectrum. Effective LQC solutions of phenomenological interest typically contain a classical period of kinetic dominance prior to slow-roll inflation, with ...
Elizaga Navascués, Beatriz +1 more
openaire +4 more sources
Dark Energy Problem, Physics of Early Universe and Some New Approaches in Gravity
Entropy, 2012 The dark energy problem is studied based on the approach associated with the cosmological term in General Relativity that is considered as a dynamic quantity.
Alexander Shalyt-Margolin
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Complex Riemannian Spacetime and Singularity-Free Black Holes and Cosmology
AxiomsAn approach is presented to address singularities in general relativity using a complex Riemannian spacetime extension. We demonstrate how this method can be applied to both black hole and cosmological singularities, specifically focusing on the ...
John W. Moffat
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