J. Triginer et D. Pavon, ON THE THERMODYNAMICS OF TILTED AND COLLISIONLESS GASES IN FRIEDMANN-ROBERTSON-WALKER SPACETIMES, Classical and quantum gravity, 12(1), 1995, pp. 199-207
Some features of the thermodynamics of tilted fluids, as witnessed by
observers comoving with the fluid, are analysed. The Gibbs equation, e
xpressed in terms of quantities measured by preferred observers comovi
ng with the metric, is obtained and the role played by the entropy pro
duction discussed. The results of Bedran and Calvao are analysed from
the the point of view of kinetic theory. We focus our attention on a c
ollisionless gases model proposed by Ellis et al and show that for the
latter u(i)/T is a conformal Killing vector in accordance with Bedran
and Calvao.