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The degree by which a function can be differentiated need not be restricted to integer values. Usually most of the field equations of physics are taken to be second order, curiosity asks what happens if this is only approximately the case…

General Relativity and Quantum Cosmology · Physics 2014-06-23 Mark D. Roberts

A deformed relativistic kinematics can be understood within a geometrical framework through a maximally symmetric momentum space. However, when considering this kind of approach, usually one works in a flat spacetime and in a curved…

General Relativity and Quantum Cosmology · Physics 2020-04-01 J. J. Relancio , S. Liberati

In recent years, the use of conformal transformation techniques has become widespread in the literature on gravitational theories alternative to general relativity, on cosmology, and on nonminimally coupled scalar fields. Typically, the…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Valerio Faraoni , Edgard Gunzig , Pasquale Nardone

Quantum cosmological models are commonly described by means of semiclassical approximations in which a smooth evolution of the expectation values of elementary geometry operators replaces the classical and singular dynamics. The advantage…

General Relativity and Quantum Cosmology · Physics 2021-04-28 Przemysław Małkiewicz , Artur Miroszewski

We study the potential effects of spacetime non-metricity in cosmology. In the spirit of Einstein-Cartan gravity, but with non-metricity replacing torsion, we consider the Einstein-Hilbert action and assume zero torsion. Adopting certain…

General Relativity and Quantum Cosmology · Physics 2023-03-29 Damianos Iosifidis , Ioannis Georgios Vogiatzis , Christos G. Tsagas

We generalize the de Broglie-Bohm (dBB) formulation of quantum mechanics to the case of quantum gravity (QG) by using the effective action for a QG theory. This is done by replacing the dBB equations of motion with the effective action…

General Relativity and Quantum Cosmology · Physics 2025-08-05 Aleksandar Mikovic

A nonintegrable phase-factor global approach to gravitation is developed by using the similarity of teleparallel gravity with electromagnetism. The phase shifts of both the COW and the gravitational Aharonov-Bohm effects are obtained. It is…

General Relativity and Quantum Cosmology · Physics 2009-11-10 R. Aldrovandi , J. G. Pereira , K. H. Vu

We propose that the size of the universe and its rate of expansion cannot be simultaneously specified with arbitrary precision, a quantum mechanical statement encoded in a deformed commutation relation for the scale factor. The deformation…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-15 Savvas M. Koushiappas

The usual Einstein's equations is modified as a one parameter family of equations in the framework of rainbow gravity. In this paper we derive the modified Friedmann-Robertson-Walker (FRW) equations when the cosmological evolution of…

General Relativity and Quantum Cosmology · Physics 2010-04-15 Yi Ling , Qingzhang Wu

An earlier paper [1] presented a gravity theory based on the optics of de Broglie waves rather than curved space-time. While the universe's geometry is flat, it agrees with the standard tests of general relativity. A second paper [2] showed…

Astrophysics · Physics 2007-05-23 Kris Krogh

The solution of the problem of describing the Friedmann observables (the Hubble law, the red shift, etc.) in quantum cosmology is proposed on the basis of the method of gaugeless Hamiltonian reduction in which the gravitational part of the…

General Relativity and Quantum Cosmology · Physics 2009-10-30 A. M. Khvedelidze , V. V. Papoyan , Yu. G. Palii , V. N. Pervushin

We have studied classical and quantum solutions of 2+1 dimensional Einstein gravity theory. Quantum theory is defined through the local conserved angular momentum and mass operators in the case of spherically symmetric space-time. The de…

General Relativity and Quantum Cosmology · Physics 2009-11-07 M. Kenmoku , T. Matsuyama , R. Sato , S. Uchida

General Relativity is an extremely successful theory, at least for weak gravitational fields, however, it breaks down at very high energies, such as in correspondence of the initial singularity. Quantum Gravity is expected to provide more…

General Relativity and Quantum Cosmology · Physics 2023-04-20 Ana Rita Ribeiro , Daniele Vernieri , Francisco S. N. Lobo

An alternative interpretation of the conformal transformations of the metric is discussed according to which the latter can be viewed as a mapping among Riemannian and Weyl-integrable spaces. A novel aspect of the conformal transformation's…

General Relativity and Quantum Cosmology · Physics 2013-01-29 Israel Quiros , Ricardo Garcia-Salcedo , Jose Edgar Madriz Aguilar , Tonatiuh Matos

The effective evolution of an inhomogeneous universe model in Einstein's theory of gravitation may be described in terms of spatially averaged scalar variables. This evolution can be modeled by solutions of a set of Friedmann equations for…

General Relativity and Quantum Cosmology · Physics 2011-02-25 Thomas Buchert

There are so many ideas that potentially explain the dark energy phenomenon, current research is focusing on a more in-depth analysis of the potential effects of modified gravity on both local and cosmic scales. In this paper we have…

General Relativity and Quantum Cosmology · Physics 2025-11-24 S. H. Shekh , Hira Sohail , Irfan Mahmood , Allah Ditta , Anil Kumar Yadav

Recently the so-called mimetic gravity approach has been used to obtain corrections to Friedmann equation of General Relativity similar to the ones present in loop quantum cosmology. In this paper, we propose an alternative way to derive…

General Relativity and Quantum Cosmology · Physics 2017-09-06 Stefano Chinaglia , Aimeric Colleaux , Sergio Zerbini

The debate on the physical relevance of conformal transformations can be faced by taking the Palatini approach into account to gravitational theories. We show that conformal transformations are not only a mathematical tool to disentangle…

High Energy Physics - Theory · Physics 2009-11-10 Gianluca Allemandi , Monica Capone , Salvatore Capozziello , Mauro Francaviglia

Recently, corrections to Einstein-Hilbert action that become important at small curvature are proposed. We discuss the first order and second order approximations to the field equations derived by the Palatini variational principle. We work…

Astrophysics · Physics 2009-11-10 Xinhe Meng , Peng Wang

A novel analytical method for f(R) modified theories without matter in Friedmann-Lemaitre-Robertson-Walker spacetimes is introduced. The equation of motion for the scale factor in terms of cosmic time is reduced to the equation for the…

General Relativity and Quantum Cosmology · Physics 2013-03-29 Silvije Domazet , Voja Radovanovic , Marko Simonovic , Hrvoje Stefancic