Comments on a Covariant Entropy Conjecture

Recently Bousso conjectured the entropy crossing a certain light-like hypersurface is bounded by the surface area. We point out a number of difficulties with this conjecture.Comment: 7 pages, 2 figures, harvmac, eps

Renormalization Group Flows from Gravity in Anti-de Sitter Space versus Black Hole No-Hair Theorems

Black hole no-hair theorems are proven using inequalities that govern the radial dependence of spherically symmetric configurations of matter fields. In this paper, we analyze the analogous inequalities for geometries dual to renormalization group flows via the AdS/CFT correspondence. These inequalities give much useful information about the qualitative properties of such flows. For Poincare invariant flows, we show that generic flows of relevant or irrelevant operators lead to singular geometries. For the case of irrelevant operators, this leads to an apparent conflict with Polchinski's decoupling theorem, and we offer two possible resolutions to this problem.Comment: 13 pages, 3 figures, harvmac, epsf, references and comments adde

Conformal Models of Two-Dimensional Turbulence

Polyakov recently showed how to use conformal field theory to describe two-dimensional turbulence. Here we construct an infinite hierarchy of solutions, both for the constant enstrophy flux cascade, and the constant energy flux cascade. We conclude with some speculations concerning the stability and physical meaning of these solutions.Comment: 17 pages, PUPT-1362, uses harvmac and tables.tex (minor typos corrected

Generalized hidden Kerr/CFT

We construct a family of vector fields that generate local symmetries in the solution space of low frequency massless field perturbations in the general Kerr geometry. This yields a one-parameter family of SL(2,R)x SL(2,R) algebras. We identify limits in which the SL(2,R)xSL(2,R) algebra contracts to an SL(2,R) symmetry of the Schwarzschild background. We note that for a particular value of our new free parameter, the symmetry algebra generates the quasinormal mode spectrum of a Kerr black hole in the large damping limit, suggesting a connection between the hidden conformal symmetry and a fundamental CFT underlying the quantum Kerr black hole.Comment: 10 page

BMS symmetry, soft particles and memory

In this work, we revisit unitary irreducible representations of the Bondi-Metzner-Sachs (BMS) group discovered by McCarthy. Representations are labelled by an infinite number of super-momenta in addition to four-momentum. Tensor products of these irreducible representations lead to particle-like states dressed by soft gravitational modes. Conservation of 4-momentum and supermomentum in the scattering of such states leads to a memory effect encoded in the outgoing soft modes. We note there exist irreducible representations corresponding to soft states with strictly vanishing four-momentum, which may nevertheless be produced by scattering of particle-like states. This fact has interesting implications for the S-matrix in gravitational theories.Comment: 19 pages, 2 figure

Pure states and black hole complementarity

The future apparent horizon of a black hole develops large stress energy due to quantum effects, unless the outgoing modes are in a thermal density matrix at the local Hawking temperature. It is shown for generic pure states that the deviation from thermality is so small that an infalling observer will see no drama on their way to the stretched horizon, providing a derivation of black hole complementarity after the Page time. Atypical pure states, and atypical observers, may of course see surprises, but that is not surprising.Comment: 17 pages, 3 figure

Quantum information erasure inside black holes

An effective field theory for infalling observers in the vicinity of a quasi-static black hole is given in terms of a freely falling lattice discretization. The lattice model successfully reproduces the thermal spectrum of outgoing Hawking radiation, as was shown by Corley and Jacobson, but can also be used to model observations made by a typical low-energy observer who enters the black hole in free fall at a prescribed time. The explicit short distance cutoff ensures that, from the viewpoint of the infalling observer, any quantum information that entered the black hole more than a scrambling time earlier has been erased by the black hole singularity. This property, combined with the requirement that outside observers need at least of order the scrambling time to extract quantum information from the black hole, ensures that a typical infalling observer does not encounter drama upon crossing the black hole horizon in a theory where black hole information is preserved for asymptotic observers.Comment: 20 pages, 3 figures, some minor correction