2002/02/07 by Gilberto M. Kremer, G. M. Kremer, F. P. Devecchi
Mathematics · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Boltzmann equation #Classical mechanics #Cosmology and Gravitation Theories #Distribution function #Entropy (arrow of time) #Entropy production #Gas Dynamics and Kinetic Theory #Gravitation #Kinetic energy #Non-equilibrium thermodynamics #Physics #Thermodynamics #gr-qc
paper · pdf · doi:10.1103/physrevd.65.083515
published as Phys.Rev. D65 (2002) 083515 · 23 pages, accepted in PRD
arxiv created 2002/02/07 · openalex publication_date 2002/04/08 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
A kinetic theory of relativistic gases in two-dimensional space-time is developed in order to obtain the equilibrium distribution function and the expressions for the fields of energy per particle, pressure, entropy per particle, and heat capacities in equilibrium. Furthermore, by using the method of Chapman and Enskog for a kinetic model of the Boltzmann equation the nonequilibrium energy-momentum tensor and the entropy production rate are determined for a universe described by a two-dimensional Robertson-Walker metric. The solutions of the gravitational field equations that consider the nonequilibrium energy-momentum tensor, associated with the coefficient of bulk viscosity, show that opposed to the four-dimensional case, the cosmic scale factor attains a maximum value at a finite time decreasing to a ``big crunch'' and that there exists a solution of the gravitational field equations corresponding to a ``false vacuum.'' The evolution of the fields of pressure, energy density, and entropy production rate with the time is also discussed.