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De Sitter Space Without Dynamical Quantum Fluctuations

Boddy, Kimberly K. and Carroll, Sean M. and Pollack, Jason (2016) De Sitter Space Without Dynamical Quantum Fluctuations. Foundations of Physics, 46 (6). pp. 702-735. ISSN 0015-9018. doi:10.1007/s10701-016-9996-8.

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We argue that, under certain plausible assumptions, de Sitter space settles into a quiescent vacuum in which there are no dynamical quantum fluctuations. Such fluctuations require either an evolving microstate, or time-dependent histories of out-of-equilibrium recording devices, which we argue are absent in stationary states. For a massive scalar field in a fixed de Sitter background, the cosmic no-hair theorem implies that the state of the patch approaches the vacuum, where there are no fluctuations. We argue that an analogous conclusion holds whenever a patch of de Sitter is embedded in a larger theory with an infinite-dimensional Hilbert space, including semiclassical quantum gravity with false vacua or complementarity in theories with at least one Minkowski vacuum. This reasoning provides an escape from the Boltzmann brain problem in such theories. It also implies that vacuum states do not uptunnel to higher-energy vacua and that perturbations do not decohere while slow-roll inflation occurs, suggesting that eternal inflation is much less common than often supposed. On the other hand, if a de Sitter patch is a closed system with a finite-dimensional Hilbert space, there will be Poincaré recurrences and dynamical Boltzmann fluctuations into lower-entropy states. Our analysis does not alter the conventional understanding of the origin of density fluctuations from primordial inflation, since reheating naturally generates a high-entropy environment and leads to decoherence, nor does it affect the existence of non-dynamical vacuum fluctuations such as those that give rise to the Casimir effect.

Item Type:Article
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URLURL TypeDescription ReadCube access Paper
Boddy, Kimberly K.0000-0003-1928-4667
Carroll, Sean M.0000-0002-4226-5758
Pollack, Jason0000-0003-4754-4905
Alternate Title:De Sitter Space Without Quantum Fluctuations
Additional Information:© 2016 Springer Science+Business Media New York. Received: 15 September 2015; Accepted: 22 February 2016; Published online: 10 March 2016. We have benefited from helpful discussions with Scott Aaronson, Charles Bennett, Alan Guth, James Hartle, Stefan Leichenauer, Spyridon Michalakis, Don Page, John Preskill, Jess Riedel, Charles Sebens, Paul Steinhardt, and several participants at the Foundational Questions Institute conference on The Physics of Information (though they might not agree with our conclusions). This research is funded in part by DOE Grant DE-FG02-92ER40701 and by the Gordon and Betty Moore Foundation through Grant 776 to the Caltech Moore Center for Theoretical Cosmology and Physics.
Group:Moore Center for Theoretical Cosmology and Physics, Walter Burke Institute for Theoretical Physics
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-92ER40701
Gordon and Betty Moore Foundation776
Subject Keywords:Cosmology – Foundations of quantum mechanics – Everett (Many-Worlds) interpretation – Quantum fluctuations
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Issue or Number:6
Record Number:CaltechAUTHORS:20150316-131744979
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Official Citation:Boddy, K.K., Carroll, S.M. & Pollack, J. Found Phys (2016) 46: 702. doi:10.1007/s10701-016-9996-8
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55796
Deposited By: Joy Painter
Deposited On:16 Mar 2015 21:15
Last Modified:10 Nov 2021 20:50

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