English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The Hamiltonian actions for extreme and non-extreme black holes are compared and contrasted and a simple derivation of the lack of entropy of extreme black holes is given. In the non-extreme case the wave function of the black hole depends on horizon degrees of freedom which give rise to the entropy. Those additional degrees of freedom are absent in the extreme case. It has been recently proposed [1], [2] that extreme black holes have zero entropy [3]. The purpose of this note is to adhere to this claim by providing an economical derivation of it. The derivation also helps to set the result in perspective and to relate it to key issues in the quantum theory of gravitation, such as the Wheeler-De Witt equation. The argument is the application to the case of an extreme black hole of an approach to black hole entropy based on the dimensional continuation of the Gauss-Bonnet theorem developed in [4]. The approach in question had been previously applied to non extreme Electronic address: cecsphy@lascar.puc.cl

Action and entropy of extreme and nonextreme black holes.