title: Thermodynamic instability of a confined gas.
abstract: The best possible cooling agent is a system with negative specific heat. If in thermal contact with a second system, any acquisition of energy due to a random fluctuation lowers its temperature, and the energy transfer in this direction is further enhanced. It continues until all the energy is extracted from the second system and their temperatures are at par. We exhibit these microcanonical features with a simple mechanical model of interacting classical gas particles in a specially confined domain and subjected to gravitation. As predicted, most of the gas particles are cooled and collect in the lowest part of the container, where the energy is carried away by a few remaining particles.
authors.affiliation: Institut für Experimentalphysik, Universität Wien, Boltzmanngasse 5, A-1090 Wien, Austria. Harald.Posch@univie.ac.at
authors.forename: Harald A
authors.initials: HA
authors.lastname: Posch
authors.forename: Walter
authors.initials: W
authors.lastname: Thirring