The information paradox and the locality bound

Hawking's argument for information loss in black hole evaporation rests on the assumption of independent Hilbert spaces for the interior and exterior of a black hole. We argue that such independence cannot be established without incorporating strong gravitational effects that undermine locality and invalidate the use of quantum field theory in a semiclassical background geometry. These considerations should also play a role in a deeper understanding of horizon complementarity.Comment: 21 pages, harvmac; v2-3. minor corrections, references adde

Modeling M-Theory Vacua via Gauged S-Duality

We construct a model of M-theory vacua using gauged S-duality and the Chan-Paton symmetries by introducing an infinite number of open string charges. In the Bechi-Rouet-Stora-Tyutin formalism, the local description of the gauged S-duality on its moduli space of vacua is fully determined by one physical state condition on the vacua. We introduce the string probe of the spatial degrees of freedom and define the increment of the cosmic time. The dimensionality of space-time and the gauge group of the low energy effective theory originate in the symmetries (with or without their breakdown) in our model. This modeling leads to the derived category formulation of the quantum mechanical world including gravity and to the concept of a non-linear potential of gauged and affinized S-duality which specifies the morphism structure of this derived category.Comment: 31 pages, version reflecting the erratum. arXiv admin note: substantial text overlap with arXiv:1102.460

Kaluza-Klein Black Holes in String Theory

Exact solutions of heterotic string theory corresponding to four-dimensional magnetic black holes in $N=4$ supergravity are described. The solutions describe the black holes in the throat limit, and consist of a tensor product of an $SU(2)$ WZW orbifold with the linear dilaton vacuum, supersymmetrized to $(1,0)$ world sheet SUSY. One dimension of the $SU(2)$ model is interpreted as a compactified fifth dimension, leading to a four dimensional solution with a Kaluza-Klein gauge field having a magnetic monopole background; this corresponds to a solution in $N=4$ supergravity, since that theory is obtained by dimensional reduction of string theory.Comment: 13p. uses Harvma

Quantization of Point Particles in 2+1 Dimensional Gravity and Space-Time Discreteness

By investigating the canonical commutation rules for gravitating quantized particles in a 2+1 dimensional world it is found that these particles live on a space-time lattice. The space-time lattice points can be characterized by three integers. Various representations are possible, the details depending on the topology chosen for energy-momentum space. We find that an $S_2\times S_1$ topology yields a physically most interesting lattice within which first quantization of Dirac particles is possible. An $S_3$ topology also gives a lattice, but does not allow first quantized particles.Comment: 23 pages Plain TeX, 3 Figure

Four Dimensional Black Holes in String Theory

Exact solutions of heterotic string theory corresponding to four-dimensional charge Q magnetic black holes are constructed as tensor products of an SU(2)/Z(2Q+2) WZW orbifold with a (0,1) supersymmetric SU(1,1)/U(1) WZW coset model. The spectrum is analyzed in some detail. ``Bad'' marginal operators are found which are argued to deform these theories to asymptotically flat black holes. Surprising behaviour is found for small values of Q, where low-energy field theory is inapplicable. At the minimal value Q=1, the theory degenerates. Renormalization group arguments are given that suggest the potential gravitational singularity of the low-energy field theory is resolved by a massive two-dimensional field theory. At Q=0, a stable, neutral ``remnant,'' of potential relevance to the black hole information paradox, is found.Comment: 37 pages + 1 figure (tar compressed and uuencoded

Three-dimensional organization of basal bodies from wild-type and δ-tubulin deletion strains of Chlamydomonas reinhardtii

Improved methods of specimen preparation and dual-axis electron tomography have been used to study the structure and organization of basal bodies in the unicellular alga Chlamydomonas reinhardtii. Novel structures have been found in both wild type and strains with mutations that affect specific tubulin isoforms. Previous studies have shown that strains lacking δ-tubulin fail to assemble the C-tubule of the basal body. Tomographic reconstructions of basal bodies from the δ-tubulin deletion mutant uni3-1 have confirmed that basal bodies contain mostly doublet microtubules. Our methods now show that the stellate fibers, which are present only in the transition zone of wild-type cells, repeat within the core of uni3-1 basal bodies. The distal striated fiber is incomplete in this mutant, rootlet microtubules can be misplaced, and multiflagellate cells have been observed. A suppressor of uni3-1, designated tua2-6, contains a mutation in α-tubulin. tua2-6; uni3-1 cells build both flagella, yet they retain defects in basal body structure and in rootlet microtubule positioning. These data suggest that the presence of specific tubulin isoforms in Chlamydomonas directly affects the assembly and function of both basal bodies and basal body-associated structures

Negative Energy Densities in Extended Sources Generating Closed Timelike Curves in General Relativity with and without Torsion

Near a spinning point particle in (2+1)-dimensional gravity (or near an infinitely thin, straight, spinning string in 3+1 dimensions) there is a region of space-time with closed timelike curves. Exact solutions for extended sources with apparently physically acceptable energy-momentum tensors, have produced the same exterior space-time structure. Here it is pointed out that in the case with torsion, closed timelike curves appear only for spin densities so high that the spin energy density is higher than the net effective energy density. In models without torsion, the presence of closed time-like curves is related to a heat flow of unphysical magnitude. This corroborates earlier arguments against the possibility of closed timelike curves in space-time geometries generated by physical sources.Comment: (to be published in Phys. Rev. D), 5 pages, REVTEX 3.0, NORDITA 93/62 A (Sept. 10/Revised Nov. 1, 1993

Quantum Theories of Dilaton Gravity

Quantization of two-dimensional dilaton gravity coupled to conformal matter is investigated. Working in conformal gauge about a fixed background metric, the theory may be viewed as a sigma model whose target space is parameterized by the dilaton $\phi$ and conformal factor $\rho$. A precise connection is given between the constraint that the theory be independent of the background metric and conformal invariance of the resulting sigma model. Although the action is renormalizable, new coupling constants must be specified at each order in perturbation theory in order to determine the quantum theory. These constants may be viewed as initial data for the beta function equations. It is argued that not all choices of this data correspond to physically sensible theories of gravity, and physically motivated constraints on the data are discussed. In particular a recently constructed subclass of initial data which reduces the full quantum theory to a soluble Liouville-like theory has energies unbounded from below and thus is unphysical. Possibilities for modifying this construction so as to avoid this difficulty are briefly discussed.Comment: 20 pages (Major additions made, including 5 pages on the relation between conformal invariance and background independence.

Gravitational Collapse of Inhomogeneous Dust in (2+1) Dimensions

We examine the gravitational collapse of spherically symmetric inhomogeneous dust in (2+1) dimensions, with cosmological constant. We obtain the analytical expressions for the interior metric. We match the solution to a vacuum exterior. We discuss the nature of the singularity formed by analyzing the outgoing radial null geodesics. We examine the formation of trapped surfaces during the collapse.Comment: Accepted for publication in CQ

Fate of the Black String Instability

Gregory and Laflamme showed that certain nonextremal black strings (and p-branes) are unstable to linearized perturbations. It is widely believed that this instability will cause the black string horizon to classically pinch off and then quantum mechanically separate, resulting in higher dimensional black holes. We argue that this cannot happen. Under very mild assumptions, classical event horizons cannot pinch off. Instead, they settle down to new static black string solutions which are not translationally invariant along the string.Comment: 11 pages, v2: few clarifications and references adde