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The standard paradigm of cosmology assumes General Relativity (GR) is a valid theory for gravity at scales in which it has not been properly tested. Developing novel tests of GR and its alternatives is crucial if we want to give strength to…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-22 Claudio Llinares

We explore nonlocally modified models of gravity, inspired by quantum loop corrections, as a mechanism for explaining current cosmic acceleration. These theories enjoy two major advantages: they allow a delayed response to cosmic events,…

Astrophysics · Physics 2011-05-31 S. Deser , R. P. Woodard

The huge amounts of undetected and exotic dark matter and dark energy needed to make general relativity work on large scales argue that we should investigate modifications of gravity. The only stable, metric-based and invariant alternative…

General Relativity and Quantum Cosmology · Physics 2018-07-06 R. P. Woodard

We briefly review the current status of nonlocal gravity (NLG), which is a classical nonlocal generalization of Einstein's theory of gravitation based on a certain analogy with the nonlocal electrodynamics of media. Nonlocal gravity thus…

General Relativity and Quantum Cosmology · Physics 2020-01-20 Bahram Mashhoon , Friedrich W. Hehl

This paper is devoted to a simple nonlocal de Sitter gravity model and its exact vacuum cosmological solutions. In the Einstein-Hilbert action with $\Lambda$ term, we introduce nonlocality by the following way: $R - 2 \Lambda =…

General Relativity and Quantum Cosmology · Physics 2022-12-28 Ivan Dimitrijevic , Branko Dragovich , Zoran Rakic , Jelena Stankovic

For the last 100 years, General Relativity (GR) has taken over the gravitational theory mantle held by Newtonian Gravity for the previous 200 years. This article reviews the status of GR in terms of its self-consistency, completeness, and…

General Relativity and Quantum Cosmology · Physics 2016-10-03 Ivan Debono , George F. Smoot

A brief account of the present status of the recent nonlocal generalization of Einstein's theory of gravitation is presented. The main physical assumptions that underlie this theory are described. We clarify the physical meaning and…

General Relativity and Quantum Cosmology · Physics 2015-01-20 B. Mashhoon

The discovery of the accelerated expansion of the universe highlighted General Relativity's inability to naturally account for dark energy without invoking a finely tuned cosmological constant. In response, a wide range of alternative…

General Relativity and Quantum Cosmology · Physics 2025-11-11 P. A. G. Monteiro , C. J. A. P. Martins

We construct a class of generalized non-local gravity (GNLG) model which is the modified theory of general relativity (GR) obtained by adding a term $m^{2n-2} R\Box^{-n}R$ to the Einstein-Hilbert action. Concretely, we not only study the…

General Relativity and Quantum Cosmology · Physics 2016-11-23 Xue Zhang , Ya-Bo Wu , Song Li , Yu-Chen Liu , Bo-Hai Chen , Yun-Tian Chai , Shuang Shu

We explore some of the cosmological implications of the recent classical nonlocal generalization of Einstein's theory of gravitation in which nonlocality is due to the gravitational memory of past events. In the Newtonian regime of this…

General Relativity and Quantum Cosmology · Physics 2016-08-24 C. Chicone , B. Mashhoon

A nonlocal gravity model (2.1) was introduced and considered recently [49], and two exact cosmological solutions in flat space were presented. The first solution is related to some radiation effects generated by nonlocal dynamics on dark…

General Relativity and Quantum Cosmology · Physics 2022-01-07 Ivan Dimitrijevic , Branko Dragovich , Zoran Rakic , Jelena Stankovic

In view to scrutinize the idea that nonlocal modifications of General Relativity could dynamically address the dark energy problem, we investigate the evolution of the Universe at infrared scales as an Infinite Derivative Gravity model of…

General Relativity and Quantum Cosmology · Physics 2024-05-03 Salvatore Capozziello , Anupam Mazumdar , Giuseppe Meluccio

It is well known that non-local theories of gravity have been a flourish arena of studies for many reasons, for instance, the UV incompleteness of General Relativity (GR). In this paper we check the consistency of ST-homogeneous…

General Relativity and Quantum Cosmology · Physics 2021-09-16 J. R. Nascimento , A. Yu. Petrov , P. J. Porfírio

The physical basis of the standard theory of general relativity is examined and a nonlocal theory of accelerated observers is described that involves a natural generalization of the hypothesis of locality. The nonlocal theory is confronted…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Bahram Mashhoon

A nonlocal gravity model which does not assume the existence of a new dimensional parameter in the action and includes a function $f(\Box^{-1} R)$, with $\Box$ the d'Alembertian operator, is studied. By specifying an exponential form for…

High Energy Physics - Theory · Physics 2013-07-24 Emilio Elizalde , Ekaterina O. Pozdeeva , Sergey Yu. Vernov , Ying-li Zhang

A classical nonlocal generalization of Einstein's theory of gravitation has recently been developed via the introduction of a scalar causal "constitutive" kernel that must ultimately be determined from observational data. It turns out that…

Astrophysics of Galaxies · Physics 2014-05-14 S. Rahvar , B. Mashhoon

In this thesis we are interested in the problem of dark energy in cosmology. In particular, we consider the possibility that this effect is due to an infrared non-local modification of the theory of General Relativity. Inspired by massive…

General Relativity and Quantum Cosmology · Physics 2016-04-26 Ermis Mitsou

We provide a systematic and updated discussion of a research line carried out by our group over the last few years, in which gravity is modified at cosmological distances by the introduction of nonlocal terms, assumed to emerge at an…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-15 Enis Belgacem , Yves Dirian , Andreas Finke , Stefano Foffa , Michele Maggiore

The introduction of General Relativity (GR) in 1915 revolutionized our understanding of gravity, but over time, its limitations in explaining phenomena like dark energy, dark matter, and quantum gravity have motivated alternative theories.…

General Relativity and Quantum Cosmology · Physics 2025-07-08 N. S. Kavya

We consider cosmological properties of modified gravity with nonlocal term $ R^p\mathcal{F}(\Box)R^q$ in its Lagrangian. Equations of motion are presented. For the flat FLRW metric, and some particular values of natural numbers $p$ and $q$…

General Relativity and Quantum Cosmology · Physics 2016-04-26 Ivan Dimitrijevic