scholarly journals No firewalls in quantum gravity: the role of discreteness of quantum geometry in resolving the information loss paradox

2015 ◽  
Vol 32 (8) ◽  
pp. 084001 ◽  
Author(s):  
Alejandro Perez
Keyword(s):  
Quantum Gravity ◽  
Information Loss ◽  
Quantum Geometry ◽  
Information Loss Paradox

The remnants in Reissner–Nordström–de Sitter quintessence black hole

2014 ◽  
Vol 29 (26) ◽  
pp. 1450123 ◽  
Author(s):  
Zhongwen Feng ◽  
Li Zhang ◽  
Xiaotao Zu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Gravity ◽  
Quantum Number ◽  
Information Loss ◽  
De Sitter ◽  
Information Loss Paradox

According to the effects of quantum gravity, we investigated the fermion tunneling from the Reissner–Nordström–de Sitter quintessence (RN–dSQ) black hole. The corrected temperature is not only determined by the mass and charge of the black hole, but also depended on the quantum number of the emitted fermion and β, which is a small value representing the effects of quantum gravity. The effects of quantum gravity slowed down the increase of the temperature and led to the remnants of the black hole. We think it is a method to avoid the information loss paradox of black holes.

scholarly journals Entanglement entropy, scale-dependent dimensions and the origin of gravity

2017 ◽  
Vol 26 (12) ◽  
pp. 1743030 ◽  
Author(s):  
Michele Arzano ◽  
Gianluca Calcagni
Keyword(s):  
Quantum Gravity ◽  
Degrees Of Freedom ◽  
Entanglement Entropy ◽  
Boundary Surface ◽  
Gravitational Theory ◽  
Einstein Gravity ◽  
Entropy Density ◽  
Spectral Dimension ◽  
Quantum Geometry

We argue that the requirement of a finite entanglement entropy of quantum degrees of freedom across a boundary surface is closely related to the phenomenon of running spectral dimension, universal in approaches to quantum gravity. If quantum geometry hinders diffusion, for instance, when its structure at some given scale is discrete or too rough, then the spectral dimension of spacetime vanishes at that scale and the entropy density blows up. A finite entanglement entropy is a key ingredient in deriving Einstein gravity in a semi-classical regime of a quantum-gravitational theory and, thus, our arguments strengthen the role of running dimensionality as an imprint of quantum geometry with potentially observable consequences.

scholarly journals Hidden messenger from quantum geometry: Towards information conservation in quantum gravity

2018 ◽  
Vol 33 (18) ◽  
pp. 1850103 ◽  
Author(s):  
Xiao-Kan Guo ◽  
Qing-Yu Cai
Keyword(s):  
Black Hole ◽  
Quantum Gravity ◽  
Loop Quantum Gravity ◽  
Information Loss ◽  
Quantum Geometry ◽  
Spin Network ◽  
General Derivation ◽  
Black Hole Information ◽  
Network States ◽  
Quantum Geometries

The back reactions of Hawking radiation allow nontrivial correlations between consecutive Hawking quanta, which gives a possible way of resolving the paradox of black hole information loss known as the hidden messenger method. In a recent work of Ma et al. [ arXiv:1711.10704 ], this method is enhanced by a general derivation using small deviations of the states of Hawking quanta off canonical typicality. In this paper, we use this typicality argument to study the effects of generic back reactions on the quantum geometries described by spin network states, and discuss the viability of entropy conservation in loop quantum gravity. We find that such back reactions lead to small area deformations of quantum geometries including those of quantum black holes. This shows that the hidden-messenger method is still viable in loop quantum gravity, which is a first step towards resolving the paradox of black hole information loss in quantum gravity.

scholarly journals Modification to the Hawking temperature of a dynamical black hole by a flow-induced supertranslation

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Hsu-Wen Chiang ◽  
Yu-Hsien Kung ◽  
Pisin Chen
Keyword(s):  
Black Hole ◽  
Coordinate Transformation ◽  
Information Loss ◽  
Hawking Temperature ◽  
Asymptotic Region ◽  
Unruh Effect ◽  
Anisotropic Flow ◽  
Information Loss Paradox ◽  
History Of ◽  
Entire History

Abstract One interesting proposal to solve the black hole information loss paradox without modifying either general relativity or quantum field theory, is the soft hair, a diffeomorphism charge that records the anisotropic radiation in the asymptotic region. This proposal, however, has been challenged, given that away from the source the soft hair behaves as a coordinate transformation that forms an Abelian group, thus unable to store any information. To maintain the spirit of the soft hair but circumvent these obstacles, we consider Hawking radiation as a probe sensitive to the entire history of the black hole evaporation, where the soft hairs on the horizon are induced by the absorption of a null anisotropic flow, generalizing the shock wave considered in [1, 2]. To do so we introduce two different time-dependent extensions of the diffeomorphism associated with the soft hair, where one is the backreaction of the anisotropic null flow, and the other is a coordinate transformation that produces the Unruh effect and a Doppler shift to the Hawking spectrum. Together, they form an exact BMS charge generator on the entire manifold that allows the nonperturbative analysis of the black hole horizon, whose surface gravity, i.e. the Hawking temperature, is found to be modified. The modification depends on an exponential average of the anisotropy of the null flow with a decay rate of 4M, suggesting the emergence of a new 2-D degree of freedom on the horizon, which could be a way out of the information loss paradox.

scholarly journals Quantum Gravity at the Corner

Universe ◽  
2018 ◽  
Vol 4 (10) ◽  
pp. 107 ◽  
Author(s):  
Laurent Freidel ◽  
Alejandro Perez
Keyword(s):  
Quantum Gravity ◽  
Symplectic Form ◽  
Direct Application ◽  
Quantum Geometry ◽  
Quantum Level ◽  
Gravitational System ◽  
Gauge Transformations ◽  
First Order ◽  
Conformal Field ◽  
First Time

We investigate the quantum geometry of a 2d surface S bounding the Cauchy slices of a 4d gravitational system. We investigate in detail for the first time the boundary symplectic current that naturally arises in the first-order formulation of general relativity in terms of the Ashtekar–Barbero connection. This current is proportional to the simplest quadratic form constructed out of the pull back to S of the triad field. We show that the would-be-gauge degrees of freedo arising from S U ( 2 ) gauge transformations plus diffeomorphisms tangent to the boundary are entirely described by the boundary 2-dimensional symplectic form, and give rise to a representation at each point of S of S L ( 2 , R ) × S U ( 2 ) . Independently of the connection with gravity, this system is very simple and rich at the quantum level, with possible connections with conformal field theory in 2d. A direct application of the quantum theory is modelling of the black horizons in quantum gravity.

scholarly journals A CRITICAL ANALYSIS OF THE COSMOLOGICAL IMPLEMENTATION OF LOOP QUANTUM GRAVITY

2012 ◽  
Vol 27 (07) ◽  
pp. 1250032 ◽  
Author(s):  
FRANCESCO CIANFRANI ◽  
GIOVANNI MONTANI
Keyword(s):  
Quantum Gravity ◽  
Quantum Cosmology ◽  
Loop Quantum Gravity ◽  
Critical Discussion ◽  
Point Of View ◽  
Graph Structure ◽  
Quantum Geometry ◽  
Cosmological Problem ◽  
New Perspective ◽  
Made In

This papers offers a critical discussion on the procedure by which Loop Quantum Cosmology (LQC) is constructed from the full Loop Quantum Gravity (LQG) theory. Revising recent issues in preserving SU(2) symmetry when quantizing the isotropic Universe, we trace a new perspective in approaching the cosmological problem within quantum geometry. The cosmological sector of LQG is reviewed and a critical point of view on LQC is presented. It is outlined how a polymer-like scale for quantum cosmology can be predicted from a proper fundamental graph underlying the homogeneous and isotropic continuous picture. However, such a minimum scale does not coincide with the choice made in LQC. Finally, the perspectives towards a consistent cosmological LQG model based on such a graph structure are discussed.

scholarly journals A quantum Rosetta Stone for the information paradox

2014 ◽  
Vol 23 (12) ◽  
pp. 1442013 ◽  
Author(s):  
Leopoldo A. Pando Zayas
Keyword(s):  
Field Theory ◽  
Black Hole ◽  
Quantum Chaos ◽  
Black Hole Physics ◽  
Information Loss ◽  
Information Paradox ◽  
Information Loss Paradox ◽  
Conformal Field ◽  
Classical Chaos ◽  
Rosetta Stone

The black hole information loss paradox epitomizes the contradictions between general relativity and quantum field theory. The AdS/conformal field theory (CFT) correspondence provides an implicit answer for the information loss paradox in black hole physics by equating a gravity theory with an explicitly unitary field theory. Gravitational collapse in asymptotically AdS spacetimes is generically turbulent. Given that the mechanism to read out the information about correlations functions in the field theory side is plagued by deterministic classical chaos, we argue that quantum chaos might provide the true Rosetta Stone for answering the information paradox in the context of the AdS/CFT correspondence.

Manifest non-locality in quantum mechanics, quantum field theory and quantum gravity

2019 ◽  
Vol 34 (28) ◽  
pp. 1941004
Author(s):  
Laurent Freidel ◽  
Robert G. Leigh ◽  
Djordje Minic
Keyword(s):  
Quantum Theory ◽  
String Theory ◽  
Quantum Gravity ◽  
Closed String ◽  
Covariant Formulation ◽  
Quantum Field ◽  
Quantum Geometry ◽  
Local Quantum ◽  
Generic Representation ◽  
Non Locality

We summarize our recent work on the foundational aspects of string theory as a quantum theory of gravity. We emphasize the hidden quantum geometry (modular spacetime) behind the generic representation of quantum theory and then stress that the same geometric structure underlies a manifestly T-duality covariant formulation of string theory, that we call metastring theory. We also discuss an effective non-commutative description of closed strings implied by intrinsic non-commutativity of closed string theory. This fundamental non-commutativity is explicit in the metastring formulation of quantum gravity. Finally we comment on the new concept of metaparticles inherent to such an effective non-commutative description in terms of bi-local quantum fields.

scholarly journals Gravitational waves and perspectives for quantum gravity

2014 ◽  
Vol 29 (30) ◽  
pp. 1430034 ◽  
Author(s):  
Ilya L. Shapiro ◽  
Ana M. Pelinson ◽  
Filipe de O. Salles
Keyword(s):  
Quantum Gravity ◽  
Gravitational Waves ◽  
Classical Solutions ◽  
Quantum Level ◽  
Quantum Matter ◽  
Higher Derivatives ◽  
Fourth Derivative ◽  
Matter Fields ◽  
Classical Background

Understanding the role of higher derivatives is probably one of the most relevant questions in quantum gravity theory. Already at the semiclassical level, when gravity is a classical background for quantum matter fields, the action of gravity should include fourth derivative terms to provide renormalizability in the vacuum sector. The same situation holds in the quantum theory of metric. At the same time, including the fourth derivative terms means the presence of massive ghosts, which are gauge-independent massive states with negative kinetic energy. At both classical and quantum level such ghosts violate stability and hence the theory becomes inconsistent. Several approaches to solve this contradiction were invented and we are proposing one more, which looks simpler than those what were considered before. We explore the dynamics of the gravitational waves on the background of classical solutions and give certain arguments that massive ghosts produce instability only when they are present as physical particles. At least on the cosmological background one can observe that if the initial frequency of the metric perturbations is much smaller than the mass of the ghost, no instabilities are present.

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