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If we separate energy in a holographic theory into an extensive part and an intrinsic part, where the extensive part is given by the cosmological constant, and assume entropy be given by the Gibbon-Hawking formula, the Cardy-Verlinde…

High Energy Physics - Theory · Physics 2009-11-10 Ke Ke , Miao Li

It is demonstrated that entropy and its density play a significant role in solving the problem of the vacuum energy density (cosmological constant) of the Universe and hence the dark energy problem. Taking this in mind, two most popular…

General Relativity and Quantum Cosmology · Physics 2011-04-07 A. E. Shalyt-Margolin

The nature of Dark Energy is still very much a mystery, and the combination of a variety of experimental tests, sensitive to different potential Dark Energy properties, will help elucidate its origins. This white paper briefly surveys the…

Astrophysics · Physics 2007-05-23 Rachel Bean , Sean Carroll , Mark Trodden

There is compelling evidence that the Universe is undergoing a late phase of accelerated expansion. One of the simplest explanations for this behaviour is the presence of dark energy. A plethora of microphysical models for dark energy have…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-25 William J. Wolf , Pedro G. Ferreira

I review the problem of dark energy focusing on the cosmological constant as the candidate and discuss its implications for the nature of gravity. Part 1 briefly overviews the currently popular `concordance cosmology' and summarises the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 T. Padmanabhan

A possible source of black hole entropy could be the entanglement of quantum fields in and out the horizon. The entanglement entropy of the ground state obeys the area law. However, a correction term proportional to a fractional power of…

High Energy Physics - Theory · Physics 2011-08-22 Ahmad Sheykhi , Seyed Hossein Hendi

We review the problem of dark energy, including a survey of theoretical models and some aspects of numerical studies.

Cosmology and Nongalactic Astrophysics · Physics 2015-03-19 Miao Li , Xiao-Dong Li , Shuang Wang , Yi Wang

We show that the concept of entropy and the dynamics of gravitation provide the linchpin in a unified scheme to understand the physics of black hole computers, space-time foam, dark energy, dark matter and the phenomenon of turbulence. We…

General Relativity and Quantum Cosmology · Physics 2020-01-08 Y. Jack Ng

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

The cosmographic technique is a powerful model-independent tool for distinguishing between competing cosmological scenarios. The key strengths and weaknesses of standard cosmography are discussed in view of healing the convergence problem…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-01 Salvatore Capozziello , Rocco D'Agostino

While observational cosmology has recently progressed fast, it revealed a serious dilemma called dark energy: an unknown source of exotic energy with negative pressure driving a current accelerating phase of the universe. All attempts so…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald

In previous works, entropic gravity and ungravity have been considered as possible solutions to the dark energy and dark matter problems. To test the viability of these models, modifications to planetary orbits are calculated for ungravity…

General Relativity and Quantum Cosmology · Physics 2025-10-09 G. Pérez Cuéllar , M. Sabido

We discuss the relationship between holographic entropy bounds and gravitating systems. In order to obtain a holographic energy density, we introduce the Bekenstein-Hawking entropy $S_{\rm BH}$ and its corresponding energy $E_{\rm BH}$…

High Energy Physics - Theory · Physics 2010-04-05 Yun Soo Myung

Some issues of the cosmological constant or dark energy are briefly reviewed. There are an increasing number of observations that constrain the equation of state of dark energy more stringently and favor the time-independent cosmological…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Jun'ichi Yokoyama

Considering the self force and radiation due to a small body in orbit (especially aperiodic) around a black hole, this paper defines a decomposition of the source into a sum over the shape preserving periodic motions of extended objects…

General Relativity and Quantum Cosmology · Physics 2013-08-02 Barak Kol

We formulate Barrow holographic dark energy, by applying the usual holographic principle at a cosmological framework, but using the Barrow entropy instead of the standard Bekenstein-Hawking one. The former is an extended black-hole entropy…

General Relativity and Quantum Cosmology · Physics 2021-01-04 Emmanuel N. Saridakis

Entropic forces have recently attracted considerable attention as ways to reformulate, retrodict, and perhaps even "explain'" classical Newtonian gravity from a rather specific thermodynamic perspective. In this article I point out that if…

High Energy Physics - Theory · Physics 2017-11-29 Matt Visser

Recent results regarding dark energy are mutually inconsistent under the $\Lambda$CDM cosmological model, hinting at the possibility of undiscovered physics. However, the currently accepted cosmological parameters come from a joint…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-08 Charles L. Steinhardt , Preston Phillips , Radoslaw Wojtak

This work summarises some of the attempts to explain the phenomenon of dark energy as an effective description of complex gravitational physics and the proper interpretation of observations. Cosmological backreaction has been shown to be…

Cosmology and Nongalactic Astrophysics · Physics 2010-03-17 Dominik J. Schwarz

Unparticle physics has been an active field since the seminal work of Georgi. Recently, many constraints on unparticles from various observations have been considered in the literature. In particular, the cosmological constraints on the…

General Relativity and Quantum Cosmology · Physics 2009-07-30 Hao Wei