Proof of the Generalized Second Law for Quasistationary Semiclassical Black Holes

A simple direct explicit proof of the generalized second law of black hole thermodynamics is given for a quasistationary semiclassical black hole.Comment: 12 pages, LaTeX, report Alberta-Thy-10-93 (revision of paper in response to Phys. Rev. Lett. referees' comments, which suffered a series of long delays

Evaporation of a Kerr black hole by emission of scalar and higher spin particles

We study the evolution of an evaporating rotating black hole, described by the Kerr metric, which is emitting either solely massless scalar particles or a mixture of massless scalar and nonzero spin particles. Allowing the hole to radiate scalar particles increases the mass loss rate and decreases the angular momentum loss rate relative to a black hole which is radiating nonzero spin particles. The presence of scalar radiation can cause the evaporating hole to asymptotically approach a state which is described by a nonzero value of $a_* \equiv a / M$. This is contrary to the conventional view of black hole evaporation, wherein all black holes spin down more rapidly than they lose mass. A hole emitting solely scalar radiation will approach a final asymptotic state described by $a_* \simeq 0.555$. A black hole that is emitting scalar particles and a canonical set of nonzero spin particles (3 species of neutrinos, a single photon species, and a single graviton species) will asymptotically approach a nonzero value of $a_*$ only if there are at least 32 massless scalar fields. We also calculate the lifetime of a primordial black hole that formed with a value of the rotation parameter $a_{*}$, the minimum initial mass of a primordial black hole that is seen today with a rotation parameter $a_{*}$, and the entropy of a black hole that is emitting scalar or higher spin particles.Comment: 22 pages, 13 figures, RevTeX format; added clearer descriptions for variables, added journal referenc

Information Flow in Entangled Quantum Systems

All information in quantum systems is, notwithstanding Bell's theorem, localised. Measuring or otherwise interacting with a quantum system S has no effect on distant systems from which S is dynamically isolated, even if they are entangled with S. Using the Heisenberg picture to analyse quantum information processing makes this locality explicit, and reveals that under some circumstances (in particular, in Einstein-Podolski-Rosen experiments and in quantum teleportation) quantum information is transmitted through 'classical' (i.e. decoherent) information channels.Comment: PostScript version now available: http://www.qubit.org/people/patrickh/Papers/InformationFlow.p

Speculative Antitrust Damages

The most important antitrust penalties are treble damage awards based on the individual harms that violations cause. For these penalties to function as an economically rational deterrent, there must be a practical mechanism for proving individual harm, and for distinguishing such harm from speculation. In this article, the authors present an account of that mechanism. First, they argue that the law\u27s measure of antitrust damages is based on a standard of net individual harm that is qualified in certain cases by a principle of net social harm. Net harm is measured by the difference between the plaintiff\u27s actual condition (given that the violation has occurred) and its but-for condition (assuming that the violation did not occur). Second, the authors show that law\u27s mechanism for proof of damages requires a projection of the but-for condition from a reasonably comparable base experience. The projection must use both the evidentiary foundation and a theoretical model to isolate the defendant\u27s illegal conduct as the difference between the actual and but-for conditions. Proof is speculative if the projection fails to account for actual or theoretical factors other than the violation that may have caused the asserted harm

Controlling the Competitor Plaintiff in Antitrust Litigation

In Misuse of the Antitrust Laws: The Competitor Plaintiff, Edward Snyder and Thomas Kauper survey a sample of private antitrust cases from the period 1973-1983 and review critically the recent economic literature on raising rivals\u27 costs as an exclusionary practice. Much in Snyder and Kauper\u27s study is worthy of comment. They have given us a useful picture of private antitrust litigation during the period covered by the sample, one that may be more accurate than a reading of reported cases from that period would suggest. Moreover, their generally critical treatment of the literature on raising rivals\u27 costs is clear and focused on the need to draw administrable policy conclusions. Most noteworthy, however, is their critique of the antitrust injury doctrine as a means of controlling unmeritorious or perverse suits by competitors. Their argument on this score - based upon their analysis of the 1973-1983 data and some more recent antitrust injury decisions - is deeply flawed and does not support their conclusion that competitor suits should be abolished. We argue here that the antitrust injury requirement and related procedural devices have evolved to address the problem of perverse competitor suits. Moreover, the solution that Snyder and Kauper offer for the problem will not likely improve upon the traditional methods of the legal system

Opaque or transparent? A link between neutrino optical depths and the characteristic duration of short gamma-ray bursts

Cosmological gamma ray bursts (GRBs) are thought to occur from violent hypercritical accretion onto stellar mass black holes, either following core collapse in massive stars or compact binary mergers. This dichotomy may be reflected in the two classes of bursts having different durations. Dynamical calculations of the evolution of these systems are essential if one is to establish characteristic, relevant timescales. We show here for the first time the result of dynamical simulations, lasting approximately one second, of post--merger accretion disks around black holes, using a realistic equation of state and considering neutrino emission processes. We find that the inclusion of neutrino optical depth effects produces important qualitative temporal and spatial transitions in the evolution and structure of the disk, which may directly reflect upon the duration and variability of short GRBs.Comment: Accepted for publication in ApJ Letter

Quantum Mechanics, Common Sense and the Black Hole Information Paradox

The purpose of this paper is to analyse, in the light of information theory and with the arsenal of (elementary) quantum mechanics (EPR correlations, copying machines, teleportation, mixing produced in sub-systems owing to a trace operation, etc.) the scenarios available on the market to resolve the so-called black-hole information paradox. We shall conclude that the only plausible ones are those where either the unitary evolution of quantum mechanics is given up, in which information leaks continuously in the course of black-hole evaporation through non-local processes, or those in which the world is polluted by an infinite number of meta-stable remnants.Comment: 15 pages, Latex, CERN-TH.6889/9

Spinning Down a Black Hole With Scalar Fields

We study the evolution of a Kerr black hole emitting scalar radiation via the Hawking process. We show that the rate at which mass and angular momentum are lost by the black hole leads to a final evolutionary state with nonzero angular momentum, namely $a/M \approx 0.555$.Comment: 4 pages (including 3 postscript figures), Revtex, uses epsf.tex, twocolumn.sty and header.sty (included). Submitted to Physical Review Letter

Intersubband magnetophonon resonances in quantum cascade structures

We report on our magnetotransport measurements of GaAs/GaAlAs quantum cascade structures in a magnetic field of up to 62 T. We observe novel quantum oscillations in tunneling current that are periodic in reciprocal magnetic field. We explain these oscillations as intersubband magnetophonon resonance due to electron relaxation by emission of either single optical or acoustic phonons. Our work also provides a non-optical in situ measurement of intersubband separations in quantum cascade structures.Comment: 5 pages, 4 figure