EXOTIC BRANES AND BLACK HOLE MICROSTATES

2013 ◽  
Vol 21 ◽  
pp. 77-91 ◽  
Author(s):  
MASAKI SHIGEMORI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Recent Progress ◽  
Codimension Two ◽  
Multi Stage ◽  
Six Dimensions

Besides ordinary branes such as D-branes, string theory is known to contain exotic branes which are related to ordinary branes by U-duality. Exotic branes are codimension-two objects and have non-trivial U-duality monodromies around them. This means that they are intrinsically non-geometric. Even if one starts with a system only with ordinary branes, exotic branes can be spontaneously generated by the supertube effect. We argue that, if one puts together more than two mutually supersymmetric branes, then, by a multi-stage supertube effect, the system will polarize into an exotic brane extending along an arbitrary surface, dubbed as the superstratum. We conjecture that, black holes in string theory, which are constructed by combining multiple ordinary branes, necessarily include exotic superstrata as their microscopic ingredients. We review the argument for the existence of superstrata and the recent progress toward constructing examples of superstrata in the framework of supergravity in six dimensions.

BLACK HOLE ENTROPY IN STRING THEORY: GOING BEYOND BEKENSTEIN AND HAWKING

2006 ◽  
Vol 15 (10) ◽  
pp. 1561-1572 ◽  
Author(s):  
ATISH DABHOLKAR
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Recent Progress ◽  
Black Hole Entropy ◽  
Quantum Corrections ◽  
Corrected Entropy

In this talk I summarize some recent progress in string theory in understanding the entropy of a class of black holes including corrections to the Bekenstein–Hawking formula. The quantum corrected entropy is in precise numerical agreement with the logarithm of the number of microstates once quantum corrections are correctly taken into account.

scholarly journals BLACK HOLE THERMODYNAMICS FROM THE POINT OF VIEW OF SUPERSTRING THEORY

2000 ◽  
Vol 15 (01) ◽  
pp. 1-44 ◽  
Author(s):  
E. T. AKHMEDOV
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Recent Progress ◽  
Black Hole Entropy ◽  
Black Hole Thermodynamics ◽  
Point Of View ◽  
Superstring Theory ◽  
Black Hole Evaporation ◽  
Statistical Explanation

In this review we try to give a pedagogical introduction to the recent progress in the resolution of old problems of black hole thermodynamics within superstring theory. We start with a brief description of classical black hole dynamics. Then, follow with the consideration of general properties of supersymmetric black holes. We conclude with the review of the statistical explanation of the black hole entropy and string theory description of the black hole evaporation.

scholarly journals RESOLVING THE BLACK HOLE INFORMATION PARADOX

2000 ◽  
Vol 15 (30) ◽  
pp. 4877-4882 ◽  
Author(s):  
SAMIR D. MATHUR
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Early Universe ◽  
Recent Progress ◽  
Information Paradox ◽  
Loss Of Information ◽  
Black Hole Information ◽  
Classical Gravity ◽  
New Criterion

The recent progress in string theory strongly suggests that formation and evaporation of black holes is a unitary process. This fact makes it imperative that we find a flaw in the semiclassical reasoning that implies a loss of information. We propose a new criterion that limits the domain of classical gravity: the hypersurfaces of a foliation cannot be stretched too much. This conjectured criterion may have important consequences for the early universe.

scholarly journals A PROPOSAL TO RESOLVE THE BLACK HOLE INFORMATION PARADOX

2002 ◽  
Vol 11 (10) ◽  
pp. 1537-1540 ◽  
Author(s):  
SAMIR D. MATHUR
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Quantum Gravity ◽  
Bound State ◽  
Nonlocal Effects ◽  
Information Paradox ◽  
Microscopic Scale ◽  
Gravity Effects ◽  
Black Hole Information

The entropy and information puzzles arising from black holes cannot be resolved if quantum gravity effects remain confined to a microscopic scale. We use concrete computations in nonperturbative string theory to argue for three kinds of nonlocal effects that operate over macroscopic distances. These effects arise when we make a bound state of a large number of branes, and occur at the correct scale to resolve the paradoxes associated with black holes.

A COMMENT ON THE BLACK HOLE INFORMATION PARADOX

2001 ◽  
Vol 16 (supp01c) ◽  
pp. 1001-1004
Author(s):  
SAMIR D. MATHUR
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Information Paradox ◽  
Loss Of Information ◽  
Black Hole Information ◽  
Classical Gravity ◽  
New Criterion

Results from string theory strongly suggest that formation and evaporation of black holes is a unitary process. Thus we must find a flaw in the semiclassical reasoning that implies a loss of information. We propose a new criterion that limits the domain of classical gravity: the hypersurfaces of a foliation cannot be stretched too much.

scholarly journals Seeking connections between wormholes, gravastars, and black holes via noncommutative geometry

2019 ◽  
Vol 35 (09) ◽  
pp. 2050059
Author(s):  
Peter K. F. Kuhfittig ◽  
Vance D. Gladney
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Energy ◽  
String Theory ◽  
Noncommutative Geometry ◽  
Thin Shell ◽  
Traversable Wormhole ◽  
Thin Shell Wormholes ◽  
Theoretical Construction

Noncommutative geometry, an offshoot of string theory, replaces point-like objects by smeared objects. The resulting uncertainty may cause a black hole to be observationally indistinguishable from a traversable wormhole, while the latter, in turn, may become observationally indistinguishable from a gravastar. The same noncommutative-geometry background allows the theoretical construction of thin-shell wormholes from gravastars and may even serve as a model for dark energy.

scholarly journals State-Space Geometry, Statistical Fluctuations, and Black Holes in String Theory

2014 ◽  
Vol 2014 ◽  
pp. 1-17
Author(s):  
Stefano Bellucci ◽  
Bhupendra Nath Tiwari
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
State Space ◽  
The State ◽  
Statistical Fluctuation ◽  
Vacuum Fluctuations ◽  
Intrinsic Geometry ◽  
Statistical Fluctuations ◽  
Space Geometry

We study the state-space geometry of various extremal and nonextremal black holes in string theory. From the notion of the intrinsic geometry, we offer a state-space perspective to the black hole vacuum fluctuations. For a given black hole entropy, we explicate the intrinsic geometric meaning of the statistical fluctuations, local and global stability conditions, and long range statistical correlations. We provide a set of physical motivations pertaining to the extremal and nonextremal black holes, namely, the meaning of the chemical geometry and physics of correlation. We illustrate the state-space configurations for general charge extremal black holes. In sequel, we extend our analysis for various possible charge and anticharge nonextremal black holes. From the perspective of statistical fluctuation theory, we offer general remarks, future directions, and open issues towards the intrinsic geometric understanding of the vacuum fluctuations and black holes in string theory.

scholarly journals EXTREMAL BLACK HOLES, HOLOGRAPHY AND COARSE GRAINING

2011 ◽  
Vol 26 (12) ◽  
pp. 1903-1971 ◽  
Author(s):  
JOAN SIMON
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Degrees Of Freedom ◽  
Recent Progress ◽  
Coarse Graining ◽  
Extremal Black Hole ◽  
Holographic Screens ◽  
Dynamical Description ◽  
Gravitational Thermodynamics ◽  
Extremal Black Holes

I review some of the concepts at the crossroads of gravitational thermodynamics, holography and quantum mechanics. First, the origin of gravitational thermodynamics due to coarse graining of quantum information is exemplified using the half-BPS sector of [Formula: see text] SYM and its LLM description in type IIB supergravity. The notion of black holes as effective geometries, its relation to the fuzzball programme and some of the puzzles raising for large black holes are discussed. Second, I review recent progress for extremal black holes, both microscopically, discussing a constituent model for stationary extremal non-BPS black holes, and semiclassically, discussing the extremal black hole/CFT conjecture. The latter is examined from the AdS3/CFT2 perspective. Third, I review the importance of the holographic principle to encode nonlocal gravity features allowing us to relate the gravitational physics of local observers with thermodynamics and the role causality plays in these arguments by identifying horizons (screens) as diathermic walls. I speculate with the emergence of an approximate CFT in the deep IR close to any horizon and its relation with an effective dynamical description of the degrees of freedom living on these holographic screens.

scholarly journals What prevents gravitational collapse in string theory?

2016 ◽  
Vol 25 (12) ◽  
pp. 1644018 ◽  
Author(s):  
Samir D. Mathur
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Quantum Gravity ◽  
State Space ◽  
Dimensional Reduction ◽  
Extra Dimension ◽  
Mass Formula ◽  
Compact Dimension ◽  
Classical Gravity

It is conventionally believed that if a ball of matter of mass [Formula: see text] has a radius close to [Formula: see text][Formula: see text]GM then it must collapse to a black hole. But string theory microstates (fuzzballs) have no horizon or singularity, and they do not collapse. We consider two simple examples from classical gravity to illustrate how this violation of our intuition happens. In each case, the ‘matter’ arises from an extra compact dimension, but the topology of this extra dimension is not trivial. The pressure and density of this matter diverge at various points, but this is only an artifact of dimensional reduction; thus, we bypass results like Buchadahl’s theorem. Such microstates give the entropy of black holes, so these topologically nontrivial constructions dominate the state space of quantum gravity.

scholarly journals DUALITIES, COMPOSITENESS AND SPACE–TIME STRUCTURE OF 4D EXTREME STRINGY BLACK HOLES

1999 ◽  
Vol 14 (07) ◽  
pp. 1015-1034 ◽  
Author(s):  
MARIANO CADONI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Bound States ◽  
Bound State ◽  
Space Time ◽  
Naked Singularities ◽  
Heterotic String Theory ◽  
Space Time Structure ◽  
Black Hole Solutions

We study the BPS black hole solutions of the (truncated) action for heterotic string theory compactified on a six-torus. The O (3,Z) duality symmetry of the theory, together with the bound state interpretation of extreme black holes, is used to generate the whole spectrum of the solutions. The corresponding space–time structures, written in terms of the string metric, are analyzed in detail. In particular, we show that only the elementary solutions present naked singularities. The bound states have either null singularities (electric solutions) or are regular (magnetic or dyonic solutions) with near-horizon geometries given by the product of two 2d spaces of constant curvature. The behavior of some of these solutions as supersymmetric attractors is discussed. We also show that our approach is very useful to understand some of the puzzling features of charged black hole solutions in string theory.

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