2002/12/31 by Johan S. Høye, J. S. Hoye, I. Brevik +4 · 11 citations
Engineering · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Quantum Electrodynamics and Casimir Effect #Thermal Radiation and Cooling Technologies #hep-th #quant-ph
paper · pdf · doi:10.1103/physreve.67.056116
published as Phys.Rev.E67:056116,2003 · 31 pages, REVTeX 4, 6 eps figures,to be published in Phys. Rev. E. This revision contains a number of small corrections and improvements, and two new references
arxiv created 2003/03/24 · openalex publication_date 2003/05/22 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The finite-temperature Casimir free energy, entropy, and internal energy are considered anew for a conventional parallel-plate configuration, in the light of current discussions in the literature. In the case of an "ideal" metal, characterized by a refractive index equal to infinity for all frequencies, we recover, via a somewhat unconventional method, conventional results for the temperature dependence, meaning that the zero-frequency transverse electric mode contributes the same as the transverse magnetic mode. For a real metal, however, approximately obeying the Drude dispersive model at low frequencies, we find that the zero-frequency transverse electric mode does not contribute at all. This would appear to lead to an observable temperature dependence and a violation of the third law of thermodynamics. It had been suggested that the source of the difficulty was the behavior of the reflection coefficient for perpendicular polarization but we show that this is not the case. By introducing a simplified model for the Casimir interaction, consisting of two harmonic oscillators interacting via a third one, we illustrate the behavior of the transverse electric field. Numerical results are presented based on the refractive index for gold. A linear temperature correction to the Casimir force between parallel plates is indeed found which should be observable in room-temperature experiments, but this does not entail any thermodynamic inconsistency.