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The various entropy bounds that exist in the literature suggest that spacetime is fundamentally discrete, and hint at an underlying relationship between geometry and "information". The foundation of this relationship is yet to be uncovered,…

General Relativity and Quantum Cosmology · Physics 2009-11-11 D. Rideout , S. Zohren

We prove the generalized Covariant Entropy Bound, $\Delta S\leq (A-A')/4G\hbar$, for light-sheets with initial area $A$ and final area $A'$. The entropy $\Delta S$ is defined as a difference of von Neumann entropies of an arbitrary state…

High Energy Physics - Theory · Physics 2014-08-06 Raphael Bousso , Horacio Casini , Zachary Fisher , Juan Maldacena

The Bousso entropy bound, in its generalized form, is investigated for the case of perfect fluids at local thermodynamic equilibrium and evidence is found that the bound is satisfied if and only if a certain local thermodynamic property…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Alessandro Pesci

In this paper, we will make an attempt to clarify the relation between three-dimensional euclidean loop quantum gravity with vanishing cosmological constant and quantum field theory in the continuum. We will argue, in particular, that in…

General Relativity and Quantum Cosmology · Physics 2018-10-22 Wolfgang Wieland

Invariance principles determine many key properties in quantum field theory, including, in particular, the appropriate form of the boundary conditions. A crucial consistency check is the proof that the resulting boundary-value problem is…

High Energy Physics - Theory · Physics 2011-04-15 Ivan G. Avramidi , Giampiero Esposito

There are many theories of quantum gravity, depending on asymptotic boundary conditions, and the amount of supersymmetry. The cosmological constant is one of the fundamental parameters that characterize different theories. If it is…

High Energy Physics - Theory · Physics 2015-06-26 T. Banks

The Bousso entropy bound is investigated for static spherically symmetric configurations of ideal gas with Bose-Einstein and Fermi-Dirac distribution function. Gas of massive particles is considered. The paper is continuation of the…

General Relativity and Quantum Cosmology · Physics 2009-07-22 Jan Gersl

A consistent implementation of quantum gravity is expected to change the familiar notions of space, time and the propagation of matter in drastic ways. This will have consequences on very small scales, but also gives rise to correction…

General Relativity and Quantum Cosmology · Physics 2009-08-26 Martin Bojowald , Golam Mortuza Hossain , Mikhail Kagan , S. Shankaranarayanan

We construct in this article a new realization of quantum geometry, which is obtained by quantizing the recently-introduced flux formulation of loop quantum gravity. In this framework, the vacuum is peaked on flat connections, and states…

General Relativity and Quantum Cosmology · Physics 2021-06-18 Benjamin Bahr , Bianca Dittrich , Marc Geiller

Quantum cosmological models are commonly described by means of semiclassical approximations in which a smooth evolution of the expectation values of elementary geometry operators replaces the classical and singular dynamics. The advantage…

General Relativity and Quantum Cosmology · Physics 2021-04-28 Przemysław Małkiewicz , Artur Miroszewski

Quantum gravity, as a fundamental theory of space-time, is expected to reveal how the universe may have started, perhaps during or before an inflationary epoch. It may then leave a potentially observable (but probably minuscule) trace in…

General Relativity and Quantum Cosmology · Physics 2015-12-17 Martin Bojowald

In loop quantum cosmology nonperturbative modification to a scalar matter field at short scales implies inflation which also means a violation of the strong energy condition. In the framework of effective Hamiltonian we discuss the issue of…

General Relativity and Quantum Cosmology · Physics 2010-10-27 Hua-Hui Xiong , Jian-Yang Zhu

We consider the fate of future singularities in the effective dynamics of loop quantum cosmology. Non-perturbative quantum geometric effects which lead to $\rho^2$ modification of the Friedmann equation at high energies result in generic…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. Sami , Parampreet Singh , Shinji Tsujikawa

Covariant models of loop quantum gravity generically imply dynamical signature change at high density. This article presents detailed derivations that show the fruitful interplay of this new kind of signature change with wave-function…

General Relativity and Quantum Cosmology · Physics 2021-05-27 Martin Bojowald , Suddhasattwa Brahma

We study quantization ambiguities in loop quantum cosmology that arise for space-times with non-zero spatial curvature and anisotropies. Motivated by lessons from different possible loop quantizations of the closed…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Parampreet Singh , Edward Wilson-Ewing

Recently a covariant entropy conjecture has been proposed for dynamical horizons. We apply this conjecture to concordance cosmological models, namely, those cosmological models filled with perfect fluids, in the presence of a positive…

High Energy Physics - Theory · Physics 2008-11-26 Song He , Hongbao Zhang

Black hole entropy is one of the few windows toward the quantum aspects of gravitation and its study over the years have highlighted the holographic nature of gravity. At the non-perturbative level in quantum gravity, promising explanations…

General Relativity and Quantum Cosmology · Physics 2018-02-14 Alexandre Feller , Etera R. Livine

From the viewpoint of local quantum field theory, this letter investigates the high-order corrections to the holographic entropy bound. As a result, the logarithmic correction term appears naturally with the definite coefficient $-{1/2}$,…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Yi Ling , Hongbao Zhang

Quantum entanglement in 3 spatial dimensions is studied in systems with physical boundaries when an entangling surface intersects the boundary. We show that there are universal logarithmic boundary terms in the entanglement R\'{e}nyi…

High Energy Physics - Theory · Physics 2015-06-15 Dmitri Fursaev

A satisfactory theory of quantum gravity will very likely require modification of our classical perception of space-time, perhaps by giving it a 'foamy' structure at scales of order the Planck length. This is expected to modify the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Subir Sarkar