On average properties of inhomogeneous fluids in general relativity II: perfect fluid cosmologies

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dc.creatorBuchert, Thomas
dc.date2001-02-12
dc.date2001-07-31
dc.date.accessioned2026-07-07T11:29:52Z
dc.date.available2026-07-07T11:29:52Z
dc.descriptionFor general relativistic spacetimes filled with an irrotational perfect fluid a generalized form of Friedmann's equations governing the expansion factor of spatially averaged portions of inhomogeneous cosmologies is derived. The averaging problem for scalar quantities is condensed into the problem of finding an `effective equation of state' including kinematical as well as dynamical `backreaction' terms that measure the departure from a standard FLRW cosmology. Applications of the averaged models are outlined including radiation-dominated and scalar field cosmologies (inflationary and dilaton/string cosmologies). In particular, the averaged equations show that the averaged scalar curvature must generically change in the course of structure formation, that an averaged inhomogeneous radiation cosmos does not follow the evolution of the standard homogeneous-isotropic model, and that an averaged inhomogeneous perfect fluid features kinematical `backreaction' terms that, in some cases, act like a free scalar field source. The free scalar field (dilaton) itself, modelled by a `stiff' fluid, is singled out as a special inhomogeneous case where the averaged equations assume a simple form.
dc.descriptionTeX 21 pages, matches published version: G.R.G., in press
dc.identifierhttps://arxiv.org/abs/gr-qc/0102049
dc.identifierhttp://arxiv.org/abs/gr-qc/0102049
dc.identifierGen.Rel.Grav.33:1381-1405,2001
dc.identifierdoi:10.1023/A:1012061725841
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/196853
dc.subjectGeneral Relativity and Quantum Cosmology
dc.subjectAstrophysics
dc.titleOn average properties of inhomogeneous fluids in general relativity II: perfect fluid cosmologies
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