Gravitational entropy: Beyond the black hole

Paul Davies, L. H. Ford, D. N. Page

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

We attempt to establish the existence of gravitational entropy for a thin spherical shell of matter as a function of radius by examining the modifications to the thermodynamics of a black hole at the center of such a shell. We show that the shell has the effect of depressing the temperature of the hole, but that small exchanges of energy between the hole and its environment at the same temperature remain isentropic in the presence of the shell. The model is generalized to include de Sitter horizons too, and we find that the shell can be positioned so that a back flow of radiation takes place from the de Sitter horizon into the hole, thus enabling the hole-plus-shell system to be used as a device for mining the Universe. In all cases our results are consistent with simple arguments indicating that there is no gravitational entropy associated with spherical shells which have not collapsed into black holes.

Original languageEnglish (US)
Pages (from-to)1700-1707
Number of pages8
JournalPhysical Review D
Volume34
Issue number6
DOIs
StatePublished - 1986
Externally publishedYes

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entropy
spherical shells
horizon
universe
thermodynamics
radii
temperature
radiation
energy

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

Cite this

Gravitational entropy : Beyond the black hole. / Davies, Paul; Ford, L. H.; Page, D. N.

In: Physical Review D, Vol. 34, No. 6, 1986, p. 1700-1707.

Research output: Contribution to journalArticle

Davies, Paul ; Ford, L. H. ; Page, D. N. / Gravitational entropy : Beyond the black hole. In: Physical Review D. 1986 ; Vol. 34, No. 6. pp. 1700-1707.
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