Showing papers on "Black hole thermodynamics published in 1979"

Entropy and black-hole thermodynamics

Abstract: The concept of entropy is examined with an eye toward gaining insight into the nature of black-hole thermodynamics. Definitions of entropy are given for ordinary classical and quantum-mechanical systems which lead to plausibility arguments for the ordinary laws of thermodynamics. The treatment of entropy for a classical system is in the spirit of the information-theory viewpoint, but by explicitly incorporating the coarse-grained observable into the definition of entropy, we eliminate any nonobjective features. The definition of entropy for a quantum-mechanical system is new, but directly parallels the classical treatment. We then apply these ideas to a self-gravitating quantum system which contains a black hole. Under some assumptions: which, although nontrivial, are by no means exotic: about the nature of such a system, it is seen that the same plausibility arguments which lead to the ordinary laws of thermodynamics for ordinary systems now lead to the laws of black-hole mechanics, including the generalized second law of thermodynamics. Thus, it appears perfectly plausible that black-hole thermodynamics is nothing more than ordinary thermodynamics applied to a self-gravitating quantum system.

Spin thermodynamics of a Kerr black hole

Abstract: According to the interpretation of a Kerr black hole as a spin system, we investigate the behaviour of the spin-thermodynamical quantities associated with the hole. In particular, the isotherms and the heat capacities are exploited.

The third law of black hole mechanics: A counterexample

Abstract: The collapse of a spherically symmetric charged thin shell in a Reissner-Nordstrom field can lead to an extreme black hole. No contradiction to the assumption of Cosmic Censorship results.

The Kerr black hole in thermal equilibrium and the νvacuum

Abstract: The nu vacuum discussed recently by Fulling (1977) in his general study of alternative vacuum states in space-times with horizons is investigated specifically for the scalar and Dirac fields in Kerr space-time. An explicit evaluation of energy flux shows that, except for the effects due to super-radiance of scalar waves, this vacuum corresponds to a black hole in thermal equilibrium with its environment.

Does black-hole entropy make sense?

Abstract: Bekenstein and Hawking saved the second law of thermodynamics near a black hole by assigning to the hole an entropyS h proportional to the area of its event horizon. It is tempting to assume thatS h possesses all the features commonly associated with the physical entropy. Kundt has shown, however, thatS h violates several reasonable physical expectations. We review his criticism, augmenting it as follows: (a)S h is a badly behaved state function requiring knowledge of the hole's future history; and (b) close analogs of event horizons in other space-times do not possess an “entropy.” We also discuss these questions: (c) IsS h suitable for all regions of a black-hole space-time? And (b) shouldS h be attributed to the exterior of a white hole? One can retainS h for the interior (respectively, exterior) of a black (respectively, white) hole, but we reject this as contrary to the information-theoretic derivation of horizon entropy given by Bekenstein. The total entropy defined by Kundt (all ordinary entropy on space-section cutting through the hole, no horizon term) and that of Bekenstein-Hawking (ordinary entropy outside horizon plus horizon term) appear to be complementary concepts with separate domains of validity. In the most natural choice, an observer inside a black hole will use Kundt's entropy, and one remaining outside that of Bekenstein-Hawking.

Zum Verdampfen und anderen Eigenschaften Schwarzer Löcher

Abstract: After a short discussion of the basic properties of black-hole physics, including the “no-hair” theorems, the hypothesis of the “cosmic censor” and the first and second law of black-hole dynamics, we proceed to the thermodynamics of black holes The concepts of entropy and temperature of a black hole are explained and the generalized second law of black-hole dynamics is presented We then discuss particle creation in the gravitational fields of black holes and their lifetime due to evaporation After a digression on chaotic cosmology the possible formation of black holes in the early universe is treated Finally we discuss the last violent stages of the evaporation process of black holes and possible observational tests A few remarks on white holes — though a totally different phenomenon — are included at the end for the sake of clarity