Energy nonconservation as a link between f(R,T) gravity and noncommutative quantum theory

Lobato, Ronaldo V.; Carvalho, G. A.; Martins, Andrey Gomes; Moraes, P. H. R. S.

doi:10.1140/epjp/i2019-12638-6

Cited by 26 publications

(17 citation statements)

References 63 publications

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“…In the second scenario the nonconservation arises naturally from quantum gravity. In a more recently letter [24], exploring this second case, they showed that the nonconservation arises from the discreteness at the Planck level, similar to our line of thought [22]. They have shown that these quantum phenomena are relevant in a cosmological scale, i.e., the underline granularity of the spacetime would lead to the emergence of an effective dark energy.…”

Section: F (R T ) Gravity and Unimodular Gravity Connection Throughsupporting

confidence: 64%

“…Particle creation is a feature in quantum field theories described in curved spacetime and in noncommutative quantum field theories, which is field theory in a noncommutative spacetime and can be interpreted as a low energy limit of a quantum gravity theory. As we stated in a previous work [22], the energy nonconservation in a four dimensional spacetime can be related to a noncommutative compact extra dimension with circular topology. In this regard, a letter by Josset et al [23] considered the unimodular gravity with violation of the conservation of energy-momentum, investigating sources of nonconservation in quantum mechanics.…”

Section: F (R T ) Gravity and Unimodular Gravity Connection Throughmentioning

confidence: 66%

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General approach to the Lagrangian ambiguity in f(R, T) gravity

et al. 2021

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The f(R, T) gravity is a theory whose gravitational action depends arbitrarily on the Ricci scalar, R, and the trace of the stress–energy tensor, T; its field equations also depend on matter Lagrangian, $$\mathscr {L}_{m}$$ L m . In the modified theories of gravity where field equations depend on Lagrangian, there is no uniqueness on the Lagrangian definition and the dynamics of the gravitational and matter fields can be different depending on the choice performed. In this work, we have eliminated the $$\mathscr {L}_{m}$$ L m dependence from f(R, T) gravity field equations by generalizing the approach of Moraes in Ref. [1]. We also propose a general approach where we argue that the trace of the energy–momentum tensor must be considered an “unknown” variable of the field equations. The trace can only depend on fundamental constants and few inputs from the standard model. Our proposal resolves two limitations: first the energy–momentum tensor of the f(R, T) gravity is not the perfect fluid one; second, the Lagrangian is not well-defined. As a test of our approach we applied it to the study of the matter era in cosmology, and the theory can successfully describe a transition between a decelerated Universe to an accelerated one without the need for dark energy.

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Section: F (R T ) Gravity and Unimodular Gravity Connection Throughsupporting

confidence: 64%

Section: F (R T ) Gravity and Unimodular Gravity Connection Throughmentioning

confidence: 66%

General approach to the Lagrangian ambiguity in f(R, T) gravity

et al. 2021

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“…Though we have probably failed to mention all existing proposals, the main ideas that have motivated current research in this field have been discussed here. In addition, interesting proposals in which there appears violation of the energy-momentum conservation include e.g., cosmological diffusion effects [96][97][98] and other physical mechanisms [99][100][101][102].…”

Section: Discussionmentioning

confidence: 99%

To Conserve, or Not to Conserve: A Review of Nonconservative Theories of Gravity

Velten

Caramês

2021

Universe

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Apart from the familiar structure firmly-rooted in the general relativistic field equations where the energy–momentum tensor has a null divergence i.e., it conserves, there exists a considerable number of extended theories of gravity allowing departures from the usual conservative framework. Many of these theories became popular in the last few years, aiming to describe the phenomenology behind dark matter and dark energy. However, within these scenarios, it is common to see attempts to preserve the conservative property of the energy–momentum tensor. Most of the time, it is done by means of some additional constraint that ensures the validity of the standard conservation law, as long as this option is available in the theory. However, if no such extra constraint is available, the theory will inevitably carry a non-trivial conservation law as part of its structure. In this work, we review some of such proposals discussing the theoretical construction leading to the non-conservation of the energy–momentum tensor.

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“…In the context of quantum theory, the non-zero divergence of the effective energy-momentum tensor can be linked to the violation of energy conservation in scattering phenomena. According to this theory, energy non-conservation can result in an energy flow between the four-dimensional spacetime and a compact extra-dimensional metric [92]. Also, the non-conservation of the matter energy-momentum tensor is related to irreversible matter creation processes, in which there is an energy flow between the gravitational field and matter due to the geometry-matter coupling, with particles permanently added to the spacetime [93,94].…”

Section: Einstein-maxwell Equation In F (R T ) Gravity and Conformal Symmetrymentioning

confidence: 99%

Stable and self-consistent charged gravastar model within the framework of $$f(R,\,T)$$ gravity

Bhar¹,

Rej²

2021

Eur. Phys. J. C

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In this work, we discuss the configuration of a gravastar (gravitational vacuum stars) in the context of $$f(R, \,T )$$ f ( R , T ) gravity by employing the Mazur–Mottola conjecture (Mazur and Mottola in Report No. LA-UR-01-5067, 2001; Mazur and Mottola, Proc Natl Acad Sci USA 101:9545, 2004). The gravastar is conceptually a substitute for a black hole theory as available in the literature and it has three regions with different equation of states. By assuming that the gravastar geometry admits a conformal Killing vector, the Einstein–Maxwell field equations have been solved in different regions of the gravastar by taking a specific equation of state as proposed by Mazur and Mottola. We match our interior spacetime to the exterior spherical region which is completely vacuum and described by the Reissner–Nordström geometry. For the particular choice of $$f(R,\,T)$$ f ( R , T ) of $$f(R, \,T )=R+2\gamma T$$ f ( R , T ) = R + 2 γ T , here we analyze various physical properties of the thin shell and also present our results graphically for these properties. The stability analysis of our present model is also studied by introducing a new parameter $$\eta $$ η and we explore the stability regions. Our proposed gravastar model in the presence of charge might be treated as a successful stable alternative of the charged black hole in the context of this version of gravity.

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Energy nonconservation as a link between f(R,T) gravity and noncommutative quantum theory

Cited by 26 publications

References 63 publications

General approach to the Lagrangian ambiguity in f(R, T) gravity

General approach to the Lagrangian ambiguity in f(R, T) gravity

To Conserve, or Not to Conserve: A Review of Nonconservative Theories of Gravity

Stable and self-consistent charged gravastar model within the framework of $$f(R,\,T)$$ gravity

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