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arXiv · hep-th/9808085

Gravitational Entropy and Global Structure

S. W. Hawking·C. J. Hunter
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Abstract

The underlying reason for the existence of gravitational entropy is traced to the impossibility of foliating topologically non-trivial Euclidean spacetimes with a time function to give a unitary Hamiltonian evolution. In $d$ dimensions the entropy can be expressed in terms of the $d-2$ obstructions to foliation, bolts and Misner strings, by a universal formula. We illustrate with a number of examples including spaces with nut charge. In these cases, the entropy is not just a quarter the area of the bolt, as it is for black holes.

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S. W. Hawking, C. J. Hunter. 1998-08-25. Gravitational Entropy and Global Structure. https://doi.org/10.1103/physrevd.59.044025

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