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Cosmological solutions for covariant canonical gauge theories of gravity are presented. The underlying covariant canonical transformation framework invokes a dynamical space-time Hamiltonian consisting of the Einstein-Hilbert term plus a…

General Relativity and Quantum Cosmology · Physics 2019-06-06 David Benisty , David Vasak , Eduardo Guendelman , Jurgen Struckmeier

Motivated by a special consideration in quantum measurement, we present a new improved energy-momentum tensor. The new tensor differs from the traditional canonical and symmetric ones, and can be derived as Nother current from a Lagrangian…

General Relativity and Quantum Cosmology · Physics 2019-03-06 Tao Lei , Zi-Wei Chen , Zhen-Lai Wang , Xiang-Song Chen*

A new concept of internal time (viewed as a scalar temporal field) is introduced which allows one to solve the energy problem in General Relativity. The law of energy conservation means that the total energy density of the full system of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ivanhoe B. Pestov

Physics invites the idea that space contains energy whose gravitational effect approximates that of Einstein's cosmological constant, Lambda; nowadays the concept is termed dark energy or quintessence. Physics also suggests the dark energy…

Astrophysics · Physics 2008-11-26 P. J. E. Peebles , Bharat Ratra

This paper analyzes the stability of the closed Einstein static universe by using linear homogeneous perturbations in the framework of energy-momentum squared gravity. This newly developed proposal resolves the primordial singularity and…

General Relativity and Quantum Cosmology · Physics 2021-08-25 M. Sharif , M. Zeeshan Gul

In the context of a gauge theory for the translation group, a conserved energy-momentum gauge current for the gravitational field is obtained. It is a true spacetime and gauge tensor, and transforms covariantly under global Lorentz…

General Relativity and Quantum Cosmology · Physics 2009-10-31 V. C. de Andrade , L. C. T. Guillen , J. G. Pereira

Assuming spherical symmetry and the semi-classical Einstein equation, we prove that, for the observers on top of the trapping horizon, the vacuum energy-momentum tensor is always that of an ingoing negative energy flux at the speed of light…

General Relativity and Quantum Cosmology · Physics 2019-07-24 Pei-Ming Ho , Yoshinori Matsuo

We analyze the early-time isotropic cosmology in the so-called energy-momentum-squared gravity (EMSG). In this theory, a $T_{\mu\nu}T^{\mu\nu}$ term is added to the Einstein-Hilbert action, which has been shown to replace the initial…

General Relativity and Quantum Cosmology · Physics 2020-03-09 Ahmed H. Barbar , Adel M. Awad , Mohammad T. AlFiky

The accelerated expansion of the universe implies the existence of an energy contribution known as dark energy. Associated with the cosmological constant in the standard model of cosmology, the nature of this dark energy is still unknown.…

General Relativity and Quantum Cosmology · Physics 2022-03-01 Ekim Taylan Hanımeli , Isaac Tutusaus , Brahim Lamine , Alain Blanchard

The cosmological constant is normally introduced as an additional term entering the Einstein-Hilbert (EH) action. In this letter we demonstrate that instead, it appears naturally from the standard EH action as an invariant term emerging…

General Physics · Physics 2024-12-19 Ivan Arraut

This work is devoted to analyze the energy of the Universe in the context of f(T) theories. Such theories are the analogous counterpart of the well known f(R) theories that, however, uses torsion instead of curvature. We obtain a general…

General Relativity and Quantum Cosmology · Physics 2013-12-05 S. C. Ulhoa , E. P. Spaniol

We examine the validity of classical energy conditions in nonsingular bouncing cosmological solutions arising in quadratic curvature gravity minimally coupled to a scalar field. Focusing on the null, weak, strong, and dominant energy…

General Relativity and Quantum Cosmology · Physics 2026-04-30 Yuki Hashimoto , Kazuharu Bamba , Sanjay Mandal

We resurrect Eddington's proposal for the gravitational action in the presence of a cosmological constant and extend it to include matter fields. We show that the Newton-Poisson equation is modified in the presence of sources and that…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-04 Maximo Banados , Pedro G. Ferreira

We discuss general properties of the conservation law associated with a local symmetry. Using Noether's theorem and a generalized Belinfante symmetrization procedure in 3+1 dimensions, a symmetric energy-momentum (pseudo) tensor for the…

High Energy Physics - Theory · Physics 2014-11-18 Dongsu Bak , D. Cangemi , R. Jackiw

Within the context of a $5D$ space-time, we construct a unified theory of gravity and electromagnetism from which the Einstein field equations and Maxwell equations emerge, with homogenous Maxwell equations appearing naturally. We also…

General Relativity and Quantum Cosmology · Physics 2010-06-17 A. Borzou , H. R. Sepangi

In this paper we show how a gravitational field generated by a given energy-momentum distribution (for all realistic cases) can be represented by distinct geometrical structures (Lorentzian, teleparallel and non null nonmetricity…

Mathematical Physics · Physics 2012-07-03 Waldyr A. Rodrigues

In General Relativity, there have been many proposals for defining the gravitational energy density, notably those proposed by Einstein, Tolman, Landau and Lifshitz, Papapetrou, M{\o}ller, and Weinberg. In this review, we firstly explored…

General Relativity and Quantum Cosmology · Physics 2022-08-12 Salvatore Capozziello , Maurizio Capriolo , Gaetano Lambiase

This paper elaborates the problem of energy-momentum in the framework of teleparallel equivalent of General Relativity. For this purpose, we consider energy-momentum prescription derived from the integral form of the constraint equations…

General Relativity and Quantum Cosmology · Physics 2010-01-07 M. Sharif , Sumaira Taj

Theoretical arguments and cosmological observations suggest that Einstein's theory of general relativity needs to be modified at high energies. One of the best motivated higher-curvature extensions of general relativity is…

General Relativity and Quantum Cosmology · Physics 2017-08-04 Laura Sberna

It is first argued that radiation by a uniformly accelerated charge in flat space-time indicates the need for a unified geometric theory of gravity and electromagnetism. Such a theory, based on a metric-affine $U_4$ manifold, is constructed…

General Physics · Physics 2018-08-30 Partha Ghose