Institut für Theoretische Physik, Karl-Franzens-Universit?t Graz, Universit?tsplatz 5, 8010 Graz, Austria, AT
Abstract:
A complete thermodynamic treatment of the Casimir effect is presented. Explicit expressions for the free and the internal
energy, the entropy and the pressure are discussed. As an example we consider the Casimir effect with different temperatures
between the plates (T) resp. outside of them (T'). For T'<T the pressure of heat radiation can eventually compensate the Casimir force and the total pressure can vanish. We consider
both an isothermal and an adiabatic treatment of the interior region. The equilibrium point (vanishing pressure) turns out
instable in the isothermal case. In the adiabatic situation we have both an instable and a stable equilibrium point, if T'/T is sufficiently small. Quantitative aspects are briefly discussed.
Received 24 February 1999 and Received in final form 26 April 1999