Noise and fluctuations in semiclassical gravity

We continue our earlier investigation of the back reaction problem in semiclassical gravity with the Schwinger-Keldysh or closed-time-path (CTP) functional formalism using the language of the decoherent history formulation of quantum mechanics. Making use of its intimate relation with the Feynman-Ve...

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Autores principales: Calzetta, E., Hu, B.L.
Formato: JOUR
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_05562821_v49_n12_p6636_Calzetta
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_05562821_v49_n12_p6636_Calzetta2023-10-03T15:35:28Z Noise and fluctuations in semiclassical gravity Calzetta, E. Hu, B.L. We continue our earlier investigation of the back reaction problem in semiclassical gravity with the Schwinger-Keldysh or closed-time-path (CTP) functional formalism using the language of the decoherent history formulation of quantum mechanics. Making use of its intimate relation with the Feynman-Vernon influence functional method, we examine the statistical mechanical meaning and show the interrelation of the many quantum processes involved in the back reaction problem, such as particle creation, decoherence, and dissipation. We show how noise and fluctuation arise naturally from the CTP formalism. We derive an expression for the CTP effective action in terms of the Bogoliubov coefficients and show how noise is related to the fluctuations in the number of particles created. In so doing we have extended the old framework of semiclassical gravity, based on the mean field theory of Einstein equation with a source given by the expectation value of the energy-momentum tensor, to that based on a Langevin-type equation, where the dynamics of the fluctuations of spacetime is driven by the quantum fluctuations of the matter field. This generalized framework is useful for the investigation of quantum processes in the early Universe involving fluctuations, vacuum instability, and phase transition phenomena as well as the nonequilibrium thermodynamics of black holes. It is also essential to an understanding of the transition from any quantum theory of gravity to classical general relativity. © 1994 The American Physical Society. Fil:Calzetta, E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_05562821_v49_n12_p6636_Calzetta
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description We continue our earlier investigation of the back reaction problem in semiclassical gravity with the Schwinger-Keldysh or closed-time-path (CTP) functional formalism using the language of the decoherent history formulation of quantum mechanics. Making use of its intimate relation with the Feynman-Vernon influence functional method, we examine the statistical mechanical meaning and show the interrelation of the many quantum processes involved in the back reaction problem, such as particle creation, decoherence, and dissipation. We show how noise and fluctuation arise naturally from the CTP formalism. We derive an expression for the CTP effective action in terms of the Bogoliubov coefficients and show how noise is related to the fluctuations in the number of particles created. In so doing we have extended the old framework of semiclassical gravity, based on the mean field theory of Einstein equation with a source given by the expectation value of the energy-momentum tensor, to that based on a Langevin-type equation, where the dynamics of the fluctuations of spacetime is driven by the quantum fluctuations of the matter field. This generalized framework is useful for the investigation of quantum processes in the early Universe involving fluctuations, vacuum instability, and phase transition phenomena as well as the nonequilibrium thermodynamics of black holes. It is also essential to an understanding of the transition from any quantum theory of gravity to classical general relativity. © 1994 The American Physical Society.
format JOUR
author Calzetta, E.
Hu, B.L.
spellingShingle Calzetta, E.
Hu, B.L.
Noise and fluctuations in semiclassical gravity
author_facet Calzetta, E.
Hu, B.L.
author_sort Calzetta, E.
title Noise and fluctuations in semiclassical gravity
title_short Noise and fluctuations in semiclassical gravity
title_full Noise and fluctuations in semiclassical gravity
title_fullStr Noise and fluctuations in semiclassical gravity
title_full_unstemmed Noise and fluctuations in semiclassical gravity
title_sort noise and fluctuations in semiclassical gravity
url http://hdl.handle.net/20.500.12110/paper_05562821_v49_n12_p6636_Calzetta
work_keys_str_mv AT calzettae noiseandfluctuationsinsemiclassicalgravity
AT hubl noiseandfluctuationsinsemiclassicalgravity
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