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The origin of the Universe's late-time accelerated expansion remains unknown. The General Relativistic Entropic Acceleration (GREA) theory offers a compelling alternative to $\Lambda$CDM, attributing cosmic acceleration to entropy growth…

In this work, we investigate the General Relativistic Entropic Acceleration (GREA) framework, in which late-time acceleration emerges from entropy production associated with the cosmological horizon, and compare its performance with the…

宇宙学与河外天体物理 · 物理学 2026-03-03 Irene Graziotti , Chiara De Leo , Matteo Martinelli

General Relativistic Entropic Acceleration (GREA) gives a general framework in which to study multiple out-of-equilibrium phenomena in the context of general relativity, like the late accelerated expansion of the universe or the formation…

广义相对论与量子宇宙学 · 物理学 2023-06-21 Juan Garcia-Bellido

The nature of the cosmological constant is a mystery. We don't understand its quantum origin but we associate it with the actual acceleration of the universe because it is the simplest description we had until recently of the present…

广义相对论与量子宇宙学 · 物理学 2026-04-15 Juan García-Bellido

Recently, a covariant formulation of non-equilibrium phenomena in the context of General Relativity was proposed in order to explain from first principles the observed accelerated expansion of the Universe, without the need for a…

宇宙学与河外天体物理 · 物理学 2022-05-03 Rubén Arjona , Llorenc Espinosa-Portales , Juan García-Bellido , Savvas Nesseris

If general relativity (GR) describes the expansion of the Universe, the observed cosmic acceleration implies the existence of a `dark energy'. However, while the Universe is on average homogeneous on large scales, it is inhomogeneous on…

天体物理学 · 物理学 2008-11-26 Aseem Paranjape , T. P. Singh

General relativistic entropic acceleration theory may explain the present cosmic acceleration from first principles without the need of introducing a cosmological constant. Following the covariant formulation of non-equilibrium phenomena in…

广义相对论与量子宇宙学 · 物理学 2021-10-20 Juan Garcia-Bellido , Llorenc Espinosa-Portales

The fundamental nature and origin of dark energy are one of the premier mysteries of theoretical physics. In General Relativity Theory, the cosmological constant $\Lambda$ is the simplest explanation for dark energy. On the other hand, the…

广义相对论与量子宇宙学 · 物理学 2022-05-27 Raja Solanki , Avik De , Sanjay Mandal , P. K. Sahoo

General Relativistic Entropic Acceleration (GREA) gives a general framework in which to study multiple out-of-equilibrium phenomena in the context of general relativity, like the late accelerated expansion of the universe or the formation…

广义相对论与量子宇宙学 · 物理学 2023-02-20 Juan Garcia-Bellido

A phenomenological formalism is presented in which the apparent acceleration of the universe is generated by large-scale structure formation, thus eliminating the coincidence and magnitude fine-tuning problems of the Cosmological Constant…

宇宙学与河外天体物理 · 物理学 2012-06-14 Brett Bochner

Explanations of the late-time cosmic acceleration within the framework of general relativity are plagued by difficulties. General relativistic models are mostly based on a dark energy field with fine-tuned, unnatural properties. There is a…

天体物理学 · 物理学 2010-04-22 Ruth Durrer , Roy Maartens

No. It is simply not plausible that cosmic acceleration could arise within the context of general relativity from a back-reaction effect of inhomogeneities in our universe, without the presence of a cosmological constant or ``dark energy.''…

广义相对论与量子宇宙学 · 物理学 2009-11-11 Akihiro Ishibashi , Robert M. Wald

We review the evidence for recently accelerating cosmological expansion or "dark energy", either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity), without any Dark Energy constituent. If…

天体物理学 · 物理学 2007-05-23 Sidney Bludman

The observed accelerated expansion of the Universe may be explained by dark energy or the breakdown of general relativity (GR) on cosmological scales. When the latter case, a modified gravity scenario, is considered, it is often assumed…

宇宙学与河外天体物理 · 物理学 2020-08-04 Jiro Matsumoto , Teppei Okumura , Misao Sasaki

Cosmic acceleration is widely believed to require either a source of negative pressure (i.e., dark energy), or a modification of gravity, which necessarily implies new degrees of freedom beyond those of Einstein gravity. In this paper we…

高能物理 - 理论 · 物理学 2017-06-28 Lasha Berezhiani , Justin Khoury , Junpu Wang

In order to explain the Late-times accelerated expansion of the Universe we must appeal to some form of Dark Energy. In the standard model of cosmology, the latter is interpreted as a Cosmological Constant $\Lambda$. However, for a number…

广义相对论与量子宇宙学 · 物理学 2021-02-18 Leonardo Giani

Cosmology is investigated within a new, scalar theory of gravitation, which is a preferred-frame bimetric theory with flat background metric. Before coming to cosmology, the motivation for an " ether theory " is exposed at length; the…

广义相对论与量子宇宙学 · 物理学 2007-05-23 Mayeul Arminjon

When recent observational evidence and the GR+FRW+CDM model are combined we obtain the result that the Universe is accelerating, where the acceleration is due to some not-yet-understood "dark sector". There has been a considerable number of…

宇宙学与河外天体物理 · 物理学 2012-05-17 Jonathan A. Pearson

Cosmic acceleration is explained quantitatively, as an apparent effect due to gravitational energy differences that arise in the decoupling of bound systems from the global expansion of the universe. "Dark energy" is a misidentification of…

广义相对论与量子宇宙学 · 物理学 2008-11-26 David L. Wiltshire

To accommodate the observed accelerated expansion of the universe, one popular idea is to invoke a driving term in the Friedmann-Lemaitre equation of dark energy which must then comprise 70% of the present cosmological energy density. We…

高能物理 - 理论 · 物理学 2011-01-27 Damien A. Easson , Paul H. Frampton , George F. Smoot
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