The Hilbert space of quantum gravity is locally finitedimensional
Abstract
In this article, we argue in a modelindependent way that the Hilbert space of quantum gravity is locally finitedimensional. In other words, the density operator describing the state corresponding to a small region of space, when such a notion makes sense, is defined on a finitedimensional factor of a larger Hilbert space. Because quantum gravity potentially describes superpositions of different geometries, it is crucial that we associate Hilbertspace factors with spatial regions only on individual decohered branches of the universal wave function. We discuss some implications of this claim, including the fact that quantumfield theory cannot be a fundamental description of nature.
 Authors:

 California Inst. of Technology (CalTech), Pasadena, CA (United States). Walter Burke Inst. for Theoretical Physics
 Publication Date:
 Research Org.:
 California Institute of Technology (CalTech), Pasadena, CA (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC), High Energy Physics (HEP) (SC25)
 OSTI Identifier:
 1598796
 Grant/Contract Number:
 SC0011632
 Resource Type:
 Accepted Manuscript
 Journal Name:
 International Journal of Modern Physics D
 Additional Journal Information:
 Journal Volume: 26; Journal Issue: 12; Journal ID: ISSN 02182718
 Publisher:
 World Scientific
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Quantum gravity; quantum foundations; decoherence
Citation Formats
Bao, Ning, Carroll, Sean M., and Singh, Ashmeet. The Hilbert space of quantum gravity is locally finitedimensional. United States: N. p., 2017.
Web. doi:10.1142/S0218271817430131.
Bao, Ning, Carroll, Sean M., & Singh, Ashmeet. The Hilbert space of quantum gravity is locally finitedimensional. United States. doi:10.1142/S0218271817430131.
Bao, Ning, Carroll, Sean M., and Singh, Ashmeet. Tue .
"The Hilbert space of quantum gravity is locally finitedimensional". United States. doi:10.1142/S0218271817430131. https://www.osti.gov/servlets/purl/1598796.
@article{osti_1598796,
title = {The Hilbert space of quantum gravity is locally finitedimensional},
author = {Bao, Ning and Carroll, Sean M. and Singh, Ashmeet},
abstractNote = {In this article, we argue in a modelindependent way that the Hilbert space of quantum gravity is locally finitedimensional. In other words, the density operator describing the state corresponding to a small region of space, when such a notion makes sense, is defined on a finitedimensional factor of a larger Hilbert space. Because quantum gravity potentially describes superpositions of different geometries, it is crucial that we associate Hilbertspace factors with spatial regions only on individual decohered branches of the universal wave function. We discuss some implications of this claim, including the fact that quantumfield theory cannot be a fundamental description of nature.},
doi = {10.1142/S0218271817430131},
journal = {International Journal of Modern Physics D},
number = 12,
volume = 26,
place = {United States},
year = {2017},
month = {10}
}
Web of Science
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Works referencing / citing this record:
How low can vacuum energy go when your fields are finitedimensional?
journal, October 2019
 Cao, ChunJun; ChatwinDavies, Aidan; Singh, Ashmeet
 International Journal of Modern Physics D, Vol. 28, Issue 14