Casimir problem of spherical dielectrics: Quantum statistical and field theoretical approaches - art. no. 051101

The Casimir free energy for a system of two dielectric concentric nonmagnet ic spherical bodies is calculated with use of a quantum statistical mechani cal method, at arbitrary temperature. By means of this rather novel method, which turns out to be quire powerful (we have shown this to he true in oth er situations also), we consider first an explicit evaluation of the free e nergy for the static case, corresponding to zero Matsubara frequency (n = 0 ). Thereafter, the time-dependent case is examined. For comparison we consi der the calculation of the free energy with use of the more commonly known field theoretical method, assuming for simplicity metallic boundary surface s.