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In general relativity, the energy conditions are invoked to restrict general energy-momentum tensors $T_{\mu\nu}$ in different frameworks, and to derive general results that hold in a variety of general contexts on physical grounds. We show…

Astrophysics · Physics 2008-11-26 J. Santos , J. S. Alcaniz , N. Pires , M. J. Reboucas

The energy conditions play an important role in the description of some important properties of the Universe, including the current accelerating expansion phase and the possible recent phase of super-acceleration. In a recent work we have…

Astrophysics · Physics 2008-09-16 M. P. Lima , S. D. P. Vitenti , M. J. Reboucas

The energy conditions play an important role in the understanding of several properties of the Universe, including the current accelerating expansion phase and the possible existence of the so-called phantom fields. We show that the…

Astrophysics · Physics 2009-06-23 M. P. Lima , S. Vitenti , M. J. Reboucas

In general relativity, the energy conditions are invoked to restrict general energy-momentum tensors on physical grounds. We show that in the standard Friedmann-Lemaitre-Robertson-Walker approach to cosmological modelling where the equation…

Astrophysics · Physics 2009-11-11 J. Santos , J. S. Alcaniz , M. J. Reboucas

In general relativity, the energy conditions are invoked to restrict general energy-momentum tensors on physical grounds. We show that in the standard Friedmann-Lemaitre-Robertson-Walker (FLRW) approach to cosmological modeling, where the…

Astrophysics · Physics 2008-12-18 J. Santos , J. S. Alcaniz , M. J. Reboucas , N. Pires

In the standard Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmological model, the energy conditions provides model-independent bounds on the behavior of the distance modulus. However, this method can not provide us the detailed information…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-20 Wen-Fei Liu , Jing Niu , Juan Li , Tong-Jie Zhang

In this exclusive study of the modified $f(Q)$ theory of gravity in the open and closed type Friedmann-Lema\^itre-Robertson-Walker (FLRW) universe model, we impose some constraints from the classical energy conditions. The viable range of…

General Relativity and Quantum Cosmology · Physics 2023-06-07 Ganesh Subramaniam , Avik De , Tee-How Loo , Yong Kheng Goh

We study the likelihood of energy condition violations in the history of the Universe. Our method is based on a set of functions that characterize energy condition violation. FLRW cosmological models are built around these "indication…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-10 Chao-Jian Wu , Cong Ma , Tong-Jie Zhang

In Phys. Rev. D 102, 024057 (2020), the authors studied energy conditions in $f(Q)$ theory following the same path as researchers handled the energy conditions in the curvature-based modified gravity theories, like $f(R)$ or $f(R,G)$…

General Relativity and Quantum Cosmology · Physics 2022-09-14 Avik De , Loo Tee How

The present thesis is focused on the study of FLRW cosmology in modified gravities and with scalar fields. The mystery of dark energy has made that the last decade, many efforts in theoretical physics have been focused on the explanation of…

High Energy Physics - Theory · Physics 2011-04-06 Diego Sáez-Gómez

The recent observations of type Ia supernovae strongly support that the universe is accelerating now and decelerated in the recent past. This may be the evidence of the breakdown of the standard Friemann equation. We consider a general…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Yungui Gong , Chang-Kui Duan

The origin of the accelerated expansion of the Universe remains an unsolved mystery in Cosmology. In this work we consider a spatially flat Friedmann-Robertson-Walker (FRW) Universe with non-relativistic matter and a single scalar field…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Remya Nair , Sanjay Jhingan , Deepak Jain

The energy conditions provide a very promising model-independent study of the current acceleration of the universe. However, in order to connect these conditions with observations, one often needs first to integrate them, and then find the…

Astrophysics · Physics 2009-06-23 Yungui Gong , Anzhong Wang

In the context of f(R, T) gravity theory for the flat Friedmann Lemaitre Robertson Walker (FLRW) model, the accelerating expansion of the universe is investigated using a specific form of the emergent Hubble parameter. Datasets from H(z),…

General Relativity and Quantum Cosmology · Physics 2025-01-16 N. Myrzakulov , S. H. Shekh , Anirudh Pradhan , Archana Dixit

In standard approach to cosmological modeling in the framework of general relativity, the energy conditions play an important role in the understanding of several properties of the Universe, including singularity theorems, the current…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-10 Di Liu , M. J. Reboucas

In this manuscript, we consider the extension of the Hilbert-Einstein action to analyze several interesting features of the theory. More specifically, the Lagrangian $f(R)$ is replaced by $f(R, L_m)$ in action, where $R$ is the Ricci…

General Relativity and Quantum Cosmology · Physics 2022-03-25 Lakhan V. Jaybhaye , Sanjay Mandal , P. K. Sahoo

The energy conditions of Einstein gravity (classical general relativity) do not require one to fix a specific equation of state. In a Friedmann-Robertson-Walker universe where the equation of state for the cosmological fluid is uncertain,…

General Relativity and Quantum Cosmology · Physics 2015-01-08 Matt Visser

The present paper examines the validity of energy bounds in a modified theory of gravity involving non-minimal coupling of torsion scalar and perfect fluid matter. In this respect, we formulate the general inequalities of energy conditions…

General Relativity and Quantum Cosmology · Physics 2015-02-11 M. Zubair , Saira Waheed

In this study of the modified $f(Q)$ theory of gravity in the spatially flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) spacetime, we explore all the affine connections compatible with the symmetric teleparallel structure; three classes…

General Relativity and Quantum Cosmology · Physics 2024-10-25 Ganesh Subramaniam , Avik De , Tee-How Loo , Yong Kheng Goh

The recent type Ia supernova data suggest that the universe is accelerating now and decelerated in recent past. This may provide the evidence that the standard Friedmann equation needs to be modified. We analyze in detail a new model in the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Yungui Gong , Xi-Ming Chen
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