Entropy of the gravitational field

Journal Article · Wed Sep 15 00:00:00 EDT 1993 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.48.2443· OSTI ID:6278191

Brandenberger, R ^[1]; Mukhanov, V ^[2]; Prokopec, T ^[1]

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1. Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)
2. Institute of Theoretical Physics, Eidgenoessische Technische Hochschule Hoenggerberg, CH-8093 Zuerich (Switzerland)

We derive a formula for the nonequilibrium entropy of a classical stochastic field in terms of correlation functions of this field. The formalism is then applied to define the entropy of gravitational perturbations (both gravitational waves and density fluctuations). We calculate this entropy in a specific cosmological model (the inflationary Universe) and find that on scales of interest in cosmology the entropy in both density perturbations and gravitational waves exceeds the entropy of statistical fluctuations of the microwave background. The nonequilibrium entropy discussed here is a measure of loss of information about the system. We discuss the origin of the entropy in our cosmological models and compare the definition of entropy in terms of correlation functions with the microcanonical definition in quantum statistical mechanics.

• DOE Contract Number: AC02-76ER03130
• OSTI ID: 6278191
• Journal Information: Physical Review, D (Particles Fields); (United States), Vol. 48:6; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
GRAVITATIONAL FIELDS
ENTROPY
INFLATIONARY UNIVERSE
CORRELATION FUNCTIONS
DISTURBANCES
STOCHASTIC PROCESSES
COSMOLOGICAL MODELS
FUNCTIONS
MATHEMATICAL MODELS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
661310* - Relativity & Gravitation- (1992-)