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In this work, we consider F(R) alternative theories of gravity with an eye to Noether symmetry through the gauge theorem. For non-vacuum models, one finds {\Lambda} like gravity with energy density of Chaplygin Gas. We also obtain the…

General Relativity and Quantum Cosmology · Physics 2018-06-19 H. R. Fazlollahi

Based on the assertion that the cosmological constant problem is essentially a quantum gravity problem, the framework which addresses the cosmological constant problem should also bear a picture for the ``quantum space-time''. In this talk…

High Energy Physics - Phenomenology · Physics 2009-10-07 M. M. Sheikh-Jabbari

This paper explores static wormhole solutions in f(Q,T) theory, where Q is the non-metricity and T is the trace of energy-momentum tensor. We derive the field equations that describe gravitational phenomena in the existence of non-metricity…

General Relativity and Quantum Cosmology · Physics 2024-11-07 M. Zeeshan Gul , M. Sharif , Shajee Shahid , Faisal Javed

We investigate the net force on a rigid Casimir cavity generated by vacuum fluctuations of electromagnetic field in three cases, de Sitter spacetime, de Sitter spacetime with weak gravitational field and Schwarzschild-de Sitter spacetime.…

High Energy Physics - Theory · Physics 2012-11-27 Xiang Chen

It is argued that the fundamental length scale for the quantum dynamics of spacetime need not be equal to the Planck length. Possibly, this new length scale is related to a nonvanishing cosmological constant or vacuum energy density.

General Relativity and Quantum Cosmology · Physics 2008-11-26 F. R. Klinkhamer

The cosmological constant problem is a fundamental issue that has puzzled researchers in the fields of theoretical physics and cosmology for a long time. It arises from the discrepancy between the observed value of the cosmological constant…

General Relativity and Quantum Cosmology · Physics 2024-01-10 Alexander I Nesterov

Quantum vacuum energy (Casimir energy) is reviewed for a mathematical audience as a topic in spectral theory. Then some one-dimensional systems are solved exactly, in terms of closed classical paths and periodic orbits. The relations among…

Mathematical Physics · Physics 2008-04-25 Stephen A. Fulling

This paper investigates static wormhole solutions through Noether symmetry approach in the context of energy-momentum squared gravity. This newly developed proposal resolves the singularity of big-bang and yields feasible cosmological…

General Relativity and Quantum Cosmology · Physics 2021-05-12 M. Sharif , M. Zeeshan Gul

A class of $k$-Essence cosmological models, with a power law kinetic term, is quantised in the mini-superspace. It is shown that for a specific configuration, corresponding to a pressureless fluid, a Schr\"odinger-type equation is obtained…

General Relativity and Quantum Cosmology · Physics 2016-12-28 C. R. Almeida , J. C. Fabris , F. Sbisá , Y. Tavakoli

This work investigates some feasible regions for the existence of traversable wormhole geometries in $f(R,G)$ gravity, where $R$ and $G$ represent the Ricci scalar and the Gauss-Bonnet invariant respectively. Three different matter contents…

General Physics · Physics 2018-11-12 M. Farasat Shamir , Saeeda Zia

Quantum gravity (or quantum spacetime) is to unify general relativity and quantum mechanics into a single theoretical framework and presented as the most important open puzzle in fundamental physics. The development of a microscopic theory…

General Physics · Physics 2025-10-24 Su-Peng Kou

A space-time crystal has recently been observed in a superfluid Bose gas. Here we construct a variational model that allows us to describe from first principles the coupling between the radial breathing mode and the higher-order axial modes…

Quantum Gases · Physics 2019-02-06 Lei Liao , Jasper Smits , Peter van der Straten , Henk Stoof

The spacetime foam structure is reviewed briefly (topogical fluctuations and virtual black hole possibility; equation of state of the foam). A model of space foam at the surface of the event horizon is introduced. The model is applied to…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Fabio Scardigli

In Poincar\'e gauge theory of gravity and in $\overline{\mbox{Poincar\'e}}$ gauge theory of gravity, we give the necessary and sufficient condition in order that the Schwarzschild space-time expressed in terms of the Schwarzschild…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Toshiharu Kawai , Eisaku Sakane , Takashi Tojo

The Casimir force between two parallel plates in the G\"odel universe is computed for a scalar field at finite temperature. It is observed that when the plates separation is comparable with the scale given by the rotation of the space-time,…

High Energy Physics - Theory · Physics 2019-08-22 Sh. Khodabakhshi , A. Shojai

At Planck-scale, spacetime is "foamy" due to quantum fluctuations predicted by quantum gravity. Here we consider the possibility of using spacetime foam-induced phase incoherence of light from distant galaxies and gamma-ray bursters to…

Astrophysics · Physics 2009-11-07 Y. Jack Ng , W. A. Christiansen , H. van Dam

We investigate the conditions under which a rotating traversable wormhole can be supported by a Casimir source in the presence of an external electric field. Extending previous studies of static Casimir wormholes and neutral rotating…

General Relativity and Quantum Cosmology · Physics 2026-05-11 Remo Garattini , Athanasios G. Tzikas

The aim of these notes is to elucidate some aspects of quantum field theory in curved spacetime, especially those relating to the notion of particles. A selection of issues relevant to wave-particle duality is given. The case of a generic…

General Physics · Physics 2008-03-13 Vladimir Mashkevich

We review recent work on wormhole geometries in the context of modified theories of gravity, in particular, in f(R) gravity and with a nonminimal curvature-matter coupling, and in the recently proposed hybrid metric-Palatini theory. In…

General Relativity and Quantum Cosmology · Physics 2013-10-18 Francisco S. N. Lobo

The neutrino flavor oscillation is studied in some classes of alternative gravity theories in a plane specified by $\theta =\pi /2$, exploiting the spherical symmetry and general equations for oscillation phases are given. We first…

General Relativity and Quantum Cosmology · Physics 2014-03-14 Sumanta Chakraborty
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