Results 1  10
of
139
The dS/CFT correspondence
 JHEP
, 2001
"... A holographic duality is proposed relating quantum gravity on dSD (Ddimensional de Sitter space) to conformal field theory on a single SD−1 ((D1)sphere), in which bulk de Sitter correlators with points on the boundary are related to CFT correlators on the sphere, and points on I + (the future bou ..."
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Cited by 196 (7 self)
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A holographic duality is proposed relating quantum gravity on dSD (Ddimensional de Sitter space) to conformal field theory on a single SD−1 ((D1)sphere), in which bulk de Sitter correlators with points on the boundary are related to CFT correlators on the sphere, and points on I + (the future boundary of dSD) are mapped to the antipodal points on SD−1 relative to those on I −. For the case of dS3, which is analyzed in some detail, the central charge of the CFT2 is computed in an analysis of the asymptotic symmetry group at I ±. This dS/CFT proposal is supported by the computation of correlation functions of a massive scalar field. In general the dual CFT may be nonunitary and (if for example there are sufficently massive stable scalars) contain complex conformal weights. We also consider the physical region O − of dS3 corresponding to the causal past of a timelike observer, whose holographic dual lives on a plane rather than a sphere. O − can be foliated by asymptotically flat spacelike slices. Time evolution along these slices is generated by
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
The annular report on noncritical string theory
, 2003
"... Recent results on the annulus partition function in Liouville field theory are applied to noncritical string theory, both below and above the critical dimension. Liouville gravity coupled to c ≤ 1 matter has a dual formulation as a matrix model. Two wellknown matrix model results are reproduced pr ..."
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Cited by 121 (5 self)
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Recent results on the annulus partition function in Liouville field theory are applied to noncritical string theory, both below and above the critical dimension. Liouville gravity coupled to c ≤ 1 matter has a dual formulation as a matrix model. Two wellknown matrix model results are reproduced precisely using the worldsheet formulation: (1) the correlation function of two macroscopic loops, and (2) the leading nonperturbative effects. The latter identifies the eigenvalue instanton amplitudes of the matrix approach with disk instantons of the worldsheet approach, thus demonstrating that the matrix model is the effective dynamics of a Dbrane realization of d ≤ 1 noncritical string theory. In the context of string theory above the critical dimension, i.e. d ≥ 25, Liouville field theory realizes twodimensional de Sitter gravity on the worldsheet. In this case, appropriate Dbrane boundary conditions on the annulus realize the Smatrix for twodimensional de Sitter gravity.
Building a better racetrack
 JHEP 0406
"... We find IIb compactifications on CalabiYau orientifolds in which all Kähler moduli are stabilized, along lines suggested by Kachru, Kallosh, Linde and Trivedi. ..."
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Cited by 114 (8 self)
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We find IIb compactifications on CalabiYau orientifolds in which all Kähler moduli are stabilized, along lines suggested by Kachru, Kallosh, Linde and Trivedi.
String propagation in the presence of cosmological singularities, JHEP 0206
, 2002
"... We study string propagation in a spacetime with positive cosmological constant, which includes a circle whose radius approaches a finite value as t  → ∞, and goes to zero at t = 0. Near this cosmological singularity, the spacetime looks like IR 1,1 / Z. In string theory, this spacetime must be ex ..."
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Cited by 67 (2 self)
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We study string propagation in a spacetime with positive cosmological constant, which includes a circle whose radius approaches a finite value as t  → ∞, and goes to zero at t = 0. Near this cosmological singularity, the spacetime looks like IR 1,1 / Z. In string theory, this spacetime must be extended by including four additional regions, two of which are compact. The other two introduce new asymptotic regions, corresponding to early and late times, respectively. States of quantum fields in this spacetime are defined in the tensor product of the two Hilbert spaces corresponding to the early time asymptotic regions, and the Smatrix describes the evolution of such states to states in the tensor product of the two late time asymptotic regions. We show that string theory provides a unique continuation of wavefunctions past the cosmological singularities, and allows one to compute the Smatrix. The incoming vacuum evolves into an outgoing state with particles. We also discuss instabilities of asymptotically timelike linear dilaton spacetimes, and the question of holography in such spaces. Finally, we briefly comment on the relation of our results to recent discussions of de Sitter space.
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
The Trouble with De Sitter Space
, 2006
"... In this paper we assume the de Sitter space version of black hole Complementarity which states that a single causal patch of de Sitter space is described as an isolated finite temperature cavity bounded by a horizon which allows no loss of information. We discuss the how the symmetries of de Sitter ..."
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Cited by 40 (3 self)
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In this paper we assume the de Sitter space version of black hole Complementarity which states that a single causal patch of de Sitter space is described as an isolated finite temperature cavity bounded by a horizon which allows no loss of information. We discuss the how the symmetries of de Sitter space should be implemented. Then we prove a no go theorem for implementing the symmetries if the entropy is finite. Thus we must either give up the finiteness of de Sitter space entropy or the exact symmetry of the classical space. Each has interesting implications for the very long time behavior. We argue that the lifetime of a de Sitter phase can not exceed the Poincare recurrence time. This is supported by recent results of Kachru, Kallosh, Linde and Trivedi.