Quantum geometry and gravitational entropy
Abstract
Most quantum states have wavefunctions that are widely spread over the accessible Hilbert space and hence do not have a good description in terms of a single classical geometry. In order to understand when geometric descriptions are possible, we exploit the AdS/CFT correspondence in the halfBPS sector of asymptotically AdS_5 x S5 universes. In this sector we devise a"coarsegrained metric operator" whose eigenstates are well described by a single spacetime topology and geometry. We show that such halfBPS universes have a nonvanishing entropy if and only if the metric is singular, and that the entropy arises from coarsegraining the geometry. Finally, we use our entropy formula to find the most entropic spacetimes with fixed asymptotic moments beyond the global charges.
 Authors:
 Publication Date:
 Research Org.:
 Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
 Sponsoring Org.:
 Physics Division
 OSTI Identifier:
 934489
 Report Number(s):
 LBNL412E
TRN: US0803916
 DOE Contract Number:
 DEAC0205CH11231
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of High Energy Physics; Journal Volume: 2007; Journal Issue: 12; Related Information: Journal Publication Date: 18 December 2007
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72; EIGENSTATES; ENTROPY; GEOMETRY; HILBERT SPACE; METRICS; SPACETIME; TOPOLOGY; AdSCFT Correspondence; Black Holes in String Theory; Gaugegravity correspondence
Citation Formats
Simon, Joan, Balasubramanian, Vijay, Czech, Bart Iomiej, Larjo, Klaus, Marolf, Donald, and Simon, Joan. Quantum geometry and gravitational entropy. United States: N. p., 2007.
Web.
Simon, Joan, Balasubramanian, Vijay, Czech, Bart Iomiej, Larjo, Klaus, Marolf, Donald, & Simon, Joan. Quantum geometry and gravitational entropy. United States.
Simon, Joan, Balasubramanian, Vijay, Czech, Bart Iomiej, Larjo, Klaus, Marolf, Donald, and Simon, Joan. Tue .
"Quantum geometry and gravitational entropy". United States.
doi:. https://www.osti.gov/servlets/purl/934489.
@article{osti_934489,
title = {Quantum geometry and gravitational entropy},
author = {Simon, Joan and Balasubramanian, Vijay and Czech, Bart Iomiej and Larjo, Klaus and Marolf, Donald and Simon, Joan},
abstractNote = {Most quantum states have wavefunctions that are widely spread over the accessible Hilbert space and hence do not have a good description in terms of a single classical geometry. In order to understand when geometric descriptions are possible, we exploit the AdS/CFT correspondence in the halfBPS sector of asymptotically AdS_5 x S5 universes. In this sector we devise a"coarsegrained metric operator" whose eigenstates are well described by a single spacetime topology and geometry. We show that such halfBPS universes have a nonvanishing entropy if and only if the metric is singular, and that the entropy arises from coarsegraining the geometry. Finally, we use our entropy formula to find the most entropic spacetimes with fixed asymptotic moments beyond the global charges.},
doi = {},
journal = {Journal of High Energy Physics},
number = 12,
volume = 2007,
place = {United States},
year = {Tue May 29 00:00:00 EDT 2007},
month = {Tue May 29 00:00:00 EDT 2007}
}

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