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We present a framework that reformulates gravitational lensing as an optical phenomenon governed by an effective refractive index, enabling exploration of modified gravity theories using undergraduate-level mathematics and optics. After…

General Relativity and Quantum Cosmology · Physics 2026-04-09 Romy Hanang Setya Budhi

Motivated by the gravity/fluid correspondence, we introduce a new method for characterizing nonlinear gravitational interactions. Namely we map the nonlinear perturbative form of the Einstein equation to the equations of motion of a…

General Relativity and Quantum Cosmology · Physics 2015-04-16 Huan Yang , Fan Zhang , Stephen R. Green , Luis Lehner

A review of the new of the problem of dark energy using modified gravity approach is considered. An explanation of the difficulties facing modern cosmology is given and different approaches are presented. We show why some models of gravity…

General Relativity and Quantum Cosmology · Physics 2014-06-18 Ahmed Alhamzawi , Rahim Alhamzawi

In this work we study classical bouncing solutions in the context of $f({\sf R},{\sf T})={\sf R}+h({\sf T})$ gravity in a flat {\sf FLRW} background using a perfect fluid as the only matter content. Our investigation is based on introducing…

General Relativity and Quantum Cosmology · Physics 2018-06-05 Hamid Shabani , Amir Hadi Ziaie

This thesis focuses on the application of numerical relativity methods to the solutions of problems in strong gravity. Our goal is the study of mergers of compact objects in the strong field regime where non-linear dynamics manifest and…

General Relativity and Quantum Cosmology · Physics 2024-08-02 Llibert Aresté Saló

Very recently, Verlinde considered a theory in which space is emergent through a holographic scenario, and proposed that gravity can be explained as an entropic force caused by changes in the information associated with the positions of…

General Relativity and Quantum Cosmology · Physics 2010-08-17 Hao Wei

Using the fluid representation, we formulate the conditions for the appearance of all four types finite-time future singularity in modified gravity in accelerating FRW universe. It stressed that number of standard quintessence/phantom DE…

High Energy Physics - Theory · Physics 2014-11-20 Shin'ichi Nojiri , Sergei D. Odintsov

The Weyssenhoff fluid is a perfect fluid with spin where the spin of the matter fields is the source of torsion in an Einstein-Cartan framework. Obukhov and Korotky showed that this fluid can be described as an effective fluid with spin in…

General Relativity and Quantum Cosmology · Physics 2008-11-26 S. D. Brechet , M. P. Hobson , A. N. Lasenby

We study the effective Lagrangian, at leading order in derivatives, that describes the propagation of density and metric fluctuations in a fluid composed by an arbitrary number of interacting components. Our results can be applied to any…

High Energy Physics - Theory · Physics 2014-06-05 Guillermo Ballesteros , Brando Bellazzini , Lorenzo Mercolli

In this work we shall study the late-time dynamics of several $F(R)$ gravity models. By appropriately expressing the field equations in terms of the redshift and of a statefinder function, we shall solve numerically the field equations…

General Relativity and Quantum Cosmology · Physics 2022-09-07 V. K. Oikonomou , Ifigeneia Giannakoudi

We propose a modified gravity theory by extending the Einstein-Hilbert action with an arbitrary function of the Ricci scalar and the Kretschmann scalar invariants. The resulting modified Friedmann equations for a spatially flat FRW universe…

General Relativity and Quantum Cosmology · Physics 2026-05-29 A. Dehyadegari , A. Sheykhi

We present a general treatment of the leading order dynamics of the collective modes of charged dilatonic $p$-brane solutions of (super)gravity theories in arbitrary backgrounds. To this end we employ the general strategy of the blackfold…

High Energy Physics - Theory · Physics 2017-09-21 Jay Armas , Jakob Gath , Vasilis Niarchos , Niels A. Obers , Andreas Vigand Pedersen

Emergent modified gravity is a canonical theory based on general covariance where the spacetime is not fundamental, but rather an emergent object. This feature allows for modifications of the classical theory and can be used to model new…

General Relativity and Quantum Cosmology · Physics 2024-02-06 Erick I. Duque

In this paper a possibility of the accelerated expansion of the large scale universe with a varying polytropic fluid of a certain type is presented. About a special role of non-gravitational interactions between dark energy and dark matter,…

General Relativity and Quantum Cosmology · Physics 2017-07-14 Martiros Khurshudyan , Asatur Khurshudyan

This is part 1 of 3 from the master's thesis: Modeling Compact Objects with Effective Field Theory, supervised by Amanda Weltman. Using the Effective Field Theory framework for extended objects and the coset construction, we build the…

High Energy Physics - Theory · Physics 2023-01-26 Irvin Martinez

This thesis is devoted to the study of gravitational theories which can be seen as modifications or generalisations of General Relativity. The motivation for considering such theories, stemming from Cosmology, High Energy Physics and…

General Relativity and Quantum Cosmology · Physics 2011-11-10 Thomas P. Sotiriou

In this paper we consider scalar-tensor theories, allowing for both conformal and disformal couplings to a fluid with a generic equation of state. We derive the effective coupling for both background cosmology and for perturbations in that…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 C. van de Bruck , G. Sculthorpe

The collapsing dynamics of relativistic fluid are explored in $f(R)$ gravity in a detailed systematic manner for the non-static spherically symmetric spacetime satisfying the equation of the conformal Killing vector. With quasi-homologous…

General Relativity and Quantum Cosmology · Physics 2024-10-03 Kazuharu Bamba , Z. Yousaf , M. Z. Bhatti , R. Nazer , Yuki Hashimoto

Versions of parameterized pseudo-Newtonian gravity theories specially designed for cosmology have been introduced in recent cosmology literature. The modifications demand a zero-pressure fluid in the context of versions of modified…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Jai-chan Hwang , Hyerim Noh , Chan-Gyung Park

This talk gives an overview of the recently-formulated Fluid/Gravity correspondence, which was developed in the context of gauge/gravity duality. Mathematically, it posits that Einstein's equations (with negative cosmological constant) in…

General Relativity and Quantum Cosmology · Physics 2011-07-19 Veronika E. Hubeny