940 research outputs found
Traversable Wormholes and Black Hole Complementarity
Black hole complementarity is incompatible with the existence of traversable
wormholes. In fact, traversable wormholes cause problems for any theory where
information comes out in the Hawking radiation.Comment: 4 pages, CALT-68-193
Generalized Conformal Symmetry and Oblique AdS/CFT Correspondence for Matrix Theory
The large N behavior of Matrix theory is discussed on the basis of the
previously proposed generalized conformal symmetry. The concept of `oblique'
AdS/CFT correspondence, in which the conformal symmetry involves both the
space-time coordinates and the string coupling constant, is proposed. Based on
the explicit predictions for two-point correlators, possible implications for
the Matrix-theory conjecture are discussed.Comment: LaTeX, 10 pages, 2 figures, written version of the talk presented at
Strings'9
Complementarity Endures: No Firewall for an Infalling Observer
We argue that the complementarity picture, as interpreted as a reference
frame change represented in quantum gravitational Hilbert space, does not
suffer from the "firewall paradox" recently discussed by Almheiri, Marolf,
Polchinski, and Sully. A quantum state described by a distant observer evolves
unitarily, with the evolution law well approximated by semi-classical field
equations in the region away from the (stretched) horizon. And yet, a classical
infalling observer does not see a violation of the equivalence principle, and
thus a firewall, at the horizon. The resolution of the paradox lies in careful
considerations on how a (semi-)classical world arises in unitary quantum
mechanics describing the whole universe/multiverse.Comment: 11 pages, 1 figure; clarifications and minor revisions; v3: a small
calculation added for clarification; v4: some corrections, conclusion
unchange
Gedanken Experiments involving Black Holes
Analysis of several gedanken experiments indicates that black hole
complementarity cannot be ruled out on the basis of known physical principles.
Experiments designed by outside observers to disprove the existence of a
quantum-mechanical stretched horizon require knowledge of Planck-scale effects
for their analysis. Observers who fall through the event horizon after sampling
the Hawking radiation cannot discover duplicate information inside the black
hole before hitting the singularity. Experiments by outside observers to detect
baryon number violation will yield significant effects well outside the
stretched horizon.Comment: 22 pages (including 7 figures), SU-ITP-93-1
Black Hole Complementarity vs. Locality
The evaporation of a large mass black hole can be described throughout most
of its lifetime by a low-energy effective theory defined on a suitably chosen
set of smooth spacelike hypersurfaces. The conventional argument for
information loss rests on the assumption that the effective theory is a local
quantum field theory. We present evidence that this assumption fails in the
context of string theory. The commutator of operators in light-front string
theory, corresponding to certain low-energy observers on opposite sides of the
event horizon, remains large even when these observers are spacelike separated
by a macroscopic distance. This suggests that degrees of freedom inside a black
hole should not be viewed as independent from those outside the event horizon.
These nonlocal effects are only significant under extreme kinematic
circumstances, such as in the high-redshift geometry of a black hole.
Commutators of space-like separated operators corresponding to ordinary
low-energy observers in Minkowski space are strongly suppressed in string
theory.Comment: 32 pages, harvmac, 3 figure
The Trouble with de Sitter Space
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 the de Sitter 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.Comment: 15 pages, 1 figure. v2: added fifth section with comments on long
time stability of de Sitter space, in which we argue that the lifetime can
not exceed the Poincare recurrence time. v3: corrected a minor error in the
appendi
Inflation and Holography in String Theory
The encoding of an inflating patch of space-time in terms of a dual theory is
discussed. Following Bousso's interpretation of the holographic principle, we
find that those are generically described not by states in the dual theory but
by density matrices. We try to implement this idea on simple deformations of
the AdS/CFT examples, and an argument is given as to why inflation is so
elusive to string theory.Comment: 15 pages, LaTeX, 2 figures. Uses psbox.te
Entropic force and its cosmological implications
We investigate a possibility of realizing the entropic force into the
cosmology. A main issue is how the holographic screen is implemented in the
Newtonian cosmology. Contrary to the relativistic realization of Friedmann
equations, we do not clarify the connection between Newtonian cosmology and
entropic force because there is no way of implementing the holographic screen
in the Newtonian cosmology.Comment: 16 pages, no figures, version "Accepted for publication in
Astrophysics & Space Science
Relating Quantum Information to Charged Black Holes
Quantum non-cloning theorem and a thought experiment are discussed for
charged black holes whose global structure exhibits an event and a Cauchy
horizon. We take Reissner-Norstr\"{o}m black holes and two-dimensional dilaton
black holes as concrete examples. The results show that the quantum non-cloning
theorem and the black hole complementarity are far from consistent inside the
inner horizon. The relevance of this work to non-local measurements is briefly
discussed.Comment: 14 pages, 2 figure
The String Landscape, Black Holes and Gravity as the Weakest Force
We conjecture a general upper bound on the strength of gravity relative to
gauge forces in quantum gravity. This implies, in particular, that in a
four-dimensional theory with gravity and a U(1) gauge field with gauge coupling
g, there is a new ultraviolet scale Lambda=g M_{Pl}, invisible to the
low-energy effective field theorist, which sets a cutoff on the validity of the
effective theory. Moreover, there is some light charged particle with mass
smaller than or equal to Lambda. The bound is motivated by arguments involving
holography and absence of remnants, the (in) stability of black holes as well
as the non-existence of global symmetries in string theory. A sharp form of the
conjecture is that there are always light "elementary" electric and magnetic
objects with a mass/charge ratio smaller than the corresponding ratio for
macroscopic extremal black holes, allowing extremal black holes to decay. This
conjecture is supported by a number of non-trivial examples in string theory.
It implies the necessary presence of new physics beneath the Planck scale, not
far from the GUT scale, and explains why some apparently natural models of
inflation resist an embedding in string theory.Comment: 20 pages, LaTeX, 5 EPS figures; v2: minor correction
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