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## Cosmologies with causal bulk viscosity

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, / 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. / Andrew Chakane 2018

Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/26217 |

Date | January 1996 |

Creators | Kgathi, Matome Abiel |

Source Sets | South African National ETD Portal |

Language | English |

Detected Language | English |

Type | Thesis |

Format | application/pdf |

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