Results 1  10
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98
Large N field theories, string theory and gravity
, 2001
"... We review the holographic correspondence between field theories and string/M theory, focusing on the relation between compactifications of string/M theory on Antide Sitter spaces and conformal field theories. We review the background for this correspondence and discuss its motivations and the evide ..."
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Cited by 1443 (45 self)
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We review the holographic correspondence between field theories and string/M theory, focusing on the relation between compactifications of string/M theory on Antide Sitter spaces and conformal field theories. We review the background for this correspondence and discuss its motivations and the evidence for its correctness. We describe the main results that have been derived from the correspondence in the regime that the field theory is approximated by classical or semiclassical gravity. We focus on the case of the N = 4 supersymmetric gauge theory in four dimensions, but we discuss also field theories in other dimensions, conformal and nonconformal, with or without supersymmetry, and in particular the relation to QCD. We also discuss some implications for black hole physics.
The holographic principle
 Rev. Mod. Phys
, 2002
"... There is strong evidence that the area of any surface limits the information content of adjacent spacetime regions, at 1.4 ×10 69 bits per square meter. We review the developments that have led to the recognition of this entropy bound, placing special emphasis on the quantum properties of black hole ..."
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Cited by 132 (9 self)
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There is strong evidence that the area of any surface limits the information content of adjacent spacetime regions, at 1.4 ×10 69 bits per square meter. We review the developments that have led to the recognition of this entropy bound, placing special emphasis on the quantum properties of black holes. The construction of lightsheets, which associate relevant spacetime regions to any
A Covariant Entropy Conjecture
 JHEP
, 1999
"... We conjecture the following entropy bound to be valid in all spacetimes admitted by Einstein’s equation: Let A be the area of any twodimensional surface. Let L be a hypersurface generated by surfaceorthogonal null geodesics with nonpositive expansion. Let S be the entropy on L. Then S ≤ A/4. We pre ..."
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Cited by 116 (25 self)
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We conjecture the following entropy bound to be valid in all spacetimes admitted by Einstein’s equation: Let A be the area of any twodimensional surface. Let L be a hypersurface generated by surfaceorthogonal null geodesics with nonpositive expansion. Let S be the entropy on L. Then S ≤ A/4. We present evidence that the bound can be saturated, but not exceeded, in cosmological solutions and in the interior of black holes. For systems with limited selfgravity it reduces to Bekenstein’s bound. Because the conjecture is manifestly time reversal invariant, its origin cannot be thermodynamic, but must be statistical. It thus places a fundamental limit on the number of degrees of freedom in nature.
Holography in general spacetimes
 JHEP
, 1999
"... We provide a backgroundindependent formulation of the holographic principle. It permits the construction of embedded hypersurfaces (screens) on which the entire bulk information can be stored at a density of no more than one bit per Planck area. Screens are constructed explicitly for AdS, Minkowski ..."
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Cited by 78 (21 self)
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We provide a backgroundindependent formulation of the holographic principle. It permits the construction of embedded hypersurfaces (screens) on which the entire bulk information can be stored at a density of no more than one bit per Planck area. Screens are constructed explicitly for AdS, Minkowski, and de Sitter spaces with and without black holes, and for cosmological solutions. The properties of screens provide clues about the character of a manifestly holographic theory.
Positive vacuum energy and the Nbound
 JHEP
, 2000
"... Abstract: We argue that the total observable entropy is bounded by the inverse of the cosmological constant. This holds for all spacetimes with a positive cosmological constant, including cosmologies dominated by ordinary matter, and recollapsing universes. The argument involves intermediate steps ..."
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Cited by 60 (11 self)
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Abstract: We argue that the total observable entropy is bounded by the inverse of the cosmological constant. This holds for all spacetimes with a positive cosmological constant, including cosmologies dominated by ordinary matter, and recollapsing universes. The argument involves intermediate steps which may be of interest in their own right. We note that entropy cannot be observed unless it lies both in the past and in the future of the observer’s history. This truncates spacetime to a diamondshaped subset wellsuited to the application of the covariant entropy bound. We further require, and derive, a novel Bekensteinlike bound on matter entropy in asymptotically de Sitter spaces. Our main result lends support to the proposal that universes with positive cosmological constant are described by a fundamental theory with only a finite
The acceleration of the universe, a challenge for string theory
 JHEP
, 2001
"... Preprint typeset in JHEP style. PAPER VERSION hepth/0104181 ..."
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Cited by 50 (2 self)
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Preprint typeset in JHEP style. PAPER VERSION hepth/0104181
Signatures of short distance physics in the cosmic microwave background,” Phys
 Rev. D
"... We systematically investigate the effect of short distance physics on the spectrum of temperature anistropies in the Cosmic Microwave Background produced during inflation. We present a general argument–assuming only low energy locality–that the size of such effects are of order H 2 /M 2, where H is ..."
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Cited by 46 (2 self)
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We systematically investigate the effect of short distance physics on the spectrum of temperature anistropies in the Cosmic Microwave Background produced during inflation. We present a general argument–assuming only low energy locality–that the size of such effects are of order H 2 /M 2, where H is the Hubble parameter during inflation, and M is the scale of the high energy physics. We evaluate the strength of such effects in a number of specific string and M theory models. In weakly coupled field theory and string theory models, the effects are far too small to be observed. In phenomenologically attractive HoˇravaWitten compactifications, the effects are much larger but still unobservable. In certain M theory models, for which the fundamental Planck scale is several orders of magnitude below the conventional scale of grand unification, the effects may be on the threshold of detectability. However, observations of both the scalar and tensor fluctuation contributions to the Cosmic Microwave Background power spectrum–with a precision near the cosmic variance limit–are necessary in order to unambiguously demonstrate the existence of these signatures of high energy physics. This is a formidable experimental challenge. January
Heretics of the false vacuum: Gravitational effects on and of vacuum decay
"... Preprint typeset in JHEP style PAPER VERSION hepth/0211 ..."
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Cited by 30 (3 self)
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Preprint typeset in JHEP style PAPER VERSION hepth/0211
Dualities versus singularities
 JHEP
, 1999
"... Preprint typeset in JHEP style. PAPER VERSION hepth/9811194 ..."
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Cited by 25 (1 self)
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Preprint typeset in JHEP style. PAPER VERSION hepth/9811194
Simple de Sitter Solutions
"... We present a framework for de Sitter model building in type IIA string theory, illustrated with specific examples. We find metastable dS minima of the potential for moduli obtained from a compactification on a product of two Nil threemanifolds (which have negative scalar curvature) combined with or ..."
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Cited by 18 (1 self)
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We present a framework for de Sitter model building in type IIA string theory, illustrated with specific examples. We find metastable dS minima of the potential for moduli obtained from a compactification on a product of two Nil threemanifolds (which have negative scalar curvature) combined with orientifolds, branes, fractional ChernSimons forms, and fluxes. As a discrete quantum number is taken large, the curvature, field strengths, inverse volume, and four dimensional string coupling become parametrically small, and the de Sitter Hubble scale can be tuned parametrically smaller than the scales of the moduli, KK, and winding mode masses. A subtle point in the construction is that although the curvature remains consistently weak, the circle fibers of the nilmanifolds become very small in this limit (though this is avoided in illustrative solutions at modest values of the parameters). In the simplest version of the construction, the heaviest moduli masses are parametrically of the same order as the lightest KK and winding masses. However, we provide a method for separating these marginally overlapping scales, and more generally the underlying supersymmetry of the model protects against large corrections to the lowenergy moduli potential. December