  We investigate the Casimir force acting between real metals at nonzero
temperature. It is shown that the zero-frequency term of Lifshitz formula has
interpretation problem in the case of real metal described by Drude model. It
happens because the scattering theory underlying Lifshitz formula is not well
formulated when the dielectric permittivity takes account of dissipation. To
give the zeroth term of Lifshitz formula the definite meaning different
prescriptions were used recently by different authors with diversed results.
These results are shown to be improper and in disagreement with experiment and
the general physical requirements. We propose the new prescription which is a
generalization of Schwinger, DeRaad and Milton recipe formulated earlier for
ideal metals. On this base the detailed numerical and analytical computations
of the temperature Casimir force are performed in configuration of two plane
plates and a spherical lens (sphere) above a plate. The corrections due to
nonzero temperature and finite conductivity found in the paper are in agreement
with the limiting case of perfect metal and fit all experimental and
theoretical requirements. Among other facts, the previous results obtained in
frames of plasma model are confirmed. It appears they are the limiting case of
Drude model computations when the relaxation parameter goes to zero. The
comparison with the Casimir force acting between dielectric test bodies is
made.
