Cosmologies with causal bulk viscosity
Date
1996
Authors
Kgathi, Matome Abiel
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Abstract
In this thesis we investigate the evolution of viscous FRW cosmological models for two
different constitutive equations for the bulk viscous pressure a, namely: The truncated
theory,,,,,,,,,,,,,,,, and the full (non-truncated] Israel-Stewart theory ...................We first review the relativistic theory of non-equilibrium thermodynamics developed by
Eckart (1940) and the essentially equivalent formulation of the theory given by Landau
and Lifshitz (1958). We give a, brief description of the relativistic second-order theories
found by Israel and Stewart (1976) and subsequently developed by Pavon, Jou, and co-workers
(1982, 1993). All this is done in order to develop the tools for the study of the
evolution of FRW cosmological models in the context of causal thermodynamics.
We find new exact and perturbative solutions of Einstein's field equations for the truncated
Israel-Stewart theory of irreversible thermodynamics. We show that viscous effects speed
up the expansion of the universe. We also consider a viscous fluid in the presence of a
" non-interacting scalar field and show that inflationary solutions exist. The full theory of
bulk viscosity is applied to dissipative FRW spacetimes. New causal viscous inflationary
solutions are presented. These solutions extend the results obtained by Maartens (1995a)
to cases where the coefficient of bulk viscosity e and the relaxation time r are independent.
Power-law solutions for the scale factor are shown to exist.
Description
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg,
in fulfilment of the requirements for the degree of Doctor of Philosophy.
Johannesburg,
Keywords
NONEQUILIBRIUM THERMODYNAMICS., VISCOSITY., COSMOLOGY--MATHEMATICAL MODELS.