The Casimir Interaction Between Real Metals at Nonzero Temperature

Abstract

Abstract This chapter begins with a discussion of the problem of the zero-frequency term in the Lifshitz formula. The thermal Casimir free energy and pressure are computed using both the plasma and the Drude model, with the tabulated optical data for the complex refractive index extrapolated by use of the Drude model. It is shown that the plasma model combined with the Lifshitz formula agrees with thermodynamics while the Drude model does not if the metal crystal lattice is perfect. Physical arguments are presented for why the Drude model is outside the application region of the Lifshitz formula. The approximate approach, based on the Leontovich impedance, is shown to be consistent with thermodynamics. The role of evanescent and traveling waves in the Casimir effect between metals is discussed. The chapter concludes with the approach using the generalized plasma-like permittivity, which is shown to be thermodynamically consistent.