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To derive black hole thermodynamics in any quantum theory of gravity, one must introduce constraints that ensure that a black hole is actually present. For a large class of black holes, the imposition of such ``horizon constraints'' allows…

General Relativity and Quantum Cosmology · Physics 2015-05-13 S. Carlip

Black holes behave as thermodynamic systems, and a central task of any quantum theory of gravity is to explain these thermal properties. A statistical mechanical description of black hole entropy once seemed remote, but today we suffer an…

General Relativity and Quantum Cosmology · Physics 2010-04-28 S. Carlip

The quest for a microscopic foundation of Thermodynamics is addressed within the Nonunitary Newtonian Gravity model through the study of a specific closed system, namely a three-dimensional harmonic nanocrystal. A numerical calculation of…

Statistical Mechanics · Physics 2020-03-12 Sergio De Filippo , Filippo Maimone , Adele Naddeo , Giovanni Scelza

A unified theory of four-dimensional gravity together with the standard model is presented, with supersymmetry breaking of M-theory at a TeV. Masses of the the known particles are derived. The cosmological constant is quantum generated to…

High Energy Physics - Theory · Physics 2007-05-23 Gordon Chalmers

The dark energy issue is focusing the attention of an incresing number of physicists all over the world. Among the possible alternatives in order to explain what as been named the "Mystery of the Millennium" are the so-called Modified…

General Relativity and Quantum Cosmology · Physics 2015-05-20 Emilio Bellini , Roberto Di Criscienzo , Lorenzo Sebastiani , Sergio Zerbini

We explore nonequilibrium features of certain operator algebras which appear in quantum gravity. The algebra of observables in a black hole background is a Type $\mathrm{II}_\infty$ von Neumann algebra. We discuss how this algebra can be…

High Energy Physics - Theory · Physics 2024-11-14 Michele Cirafici

Non-rotating black holes in three and four dimensions are shown to possess a canonical entropy obeying the Bekenstein-Hawking area law together with a leading correction (for large horizon areas) given by the logarithm of the area with a…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Ashok Chatterjee , Parthasarathi Majumdar

We obtain an exact spherically symmetric and magnetically charged black hole solution in 4D Einstein-Gauss-Bonnet gravity coupled with rational nonlinear electrodynamics. The thermodynamics of our model is studied. We calculate the Hawking…

General Physics · Physics 2021-06-02 S. I. Kruglov

Black hole solutions in pure quadratic theories of gravity are interesting since they allow to formulate a set of scale-invariant thermodynamics laws. Recently, we have proven that static scale-invariant black holes have a well-defined…

General Relativity and Quantum Cosmology · Physics 2015-07-24 Guido Cognola , Massimiliano Rinaldi , Luciano Vanzo

The entropy of black holes in modified theories of gravity is examined in the Palatini formalism using the Noether Charge approach. It is shown that, if the gravitational coupling constant is properly identified, the entropy of a black hole…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Dan N. Vollick

Two types of self-gravitating particle solutions found in several theories with non-Abelian fields are smoothly connected by a family of non-trivial black holes. There exists a maximum point of the black hole entropy, where the stability of…

General Relativity and Quantum Cosmology · Physics 2009-10-22 K. Maeda , T. Tachizawa , T. Torii , T. Maki

In the standard viewpoint, the temperature of a stationary black hole is proportional to its surface gravity, $T_H=\hbar\kappa/2\pi$. This is a semiclassical result and the quantum gravity effects are not taken into consideration. This…

General Relativity and Quantum Cosmology · Physics 2009-11-19 Li Xiang , X. Q. Wen

Motivated by some recent speculative attempts to model the dark energy, scalar fields with negative kinetic energy coupled to gravity without a cosmological constant are considered. It is shown that in the presence of an ordinary fluid, any…

High Energy Physics - Theory · Physics 2007-05-23 G. W. Gibbons

Along this review, we focus on the study of several properties of modified gravity theories, in particular on black-hole solutions and its comparison with those solutions in General Relativity, and on Friedmann-Lemaitre-Robertson-Walker…

General Relativity and Quantum Cosmology · Physics 2015-06-05 A. de la Cruz-Dombriz , D. Saez-Gomez

An analysis of some modified gravity models, based on the study of pure Schwarzschild and of Schwarzschild-de Sitter black holes, and involving the use of the Noether charge method, is carried out. Corrections to the classical Einsteinian…

High Energy Physics - Theory · Physics 2008-11-26 F. Briscese , E. Elizalde

We investigate exact charged and uncharged black hole solutions in a (2+1)-dimensional spacetime within the framework of quadratic form of $f(\mathbb{Q})$ symmetric teleparallel gravity, where $\mathbb{Q}$ is the non-metricity scalar. By…

General Relativity and Quantum Cosmology · Physics 2026-01-13 G. G. L. Nashed , Salvatore Capozziello

We define, by an integral of geometric quantities over a spherical shell of arbitrary radius, an invariant gravitational entropy. This definition relies on defining a gravitational energy and pressure, and it reduces at the horizon of both…

High Energy Physics - Theory · Physics 2015-06-03 Ram Brustein , A. J. M. Medved

We review (and extend) the analysis of general theories of all interactions (gravity included) where the mass scales are due to dimensional transmutation. Quantum consistency requires the presence of terms in the action with four…

High Energy Physics - Theory · Physics 2021-04-12 Alberto Salvio

We show that that four dimensional conformal gravity plus a simple Neumann boundary condition can be used to get the semiclassical (or tree level) wavefunction of the universe of four dimensional asymptotically de-Sitter or Euclidean…

High Energy Physics - Theory · Physics 2011-06-10 Juan Maldacena

Regular black holes have become a popular alternative to the singular mathematical black holes predicted by general relativity as they circumvent mathematical pathologies associated with the singularity while preserving crucial black hole…

General Relativity and Quantum Cosmology · Physics 2024-08-15 Ioannis Soranidis