Collision integral in Friedman world

A chain of equations for the relativistic distribution functions of charged particles in an isotropic spatially plane Friedman world is obtained by introducing a random function. The chain is employed to derive the relativistic kinetic equation with account for the effect of the gravitational field on the collision act. At nonrelativistic velocities the collision integral is identical to the Landau collision integral only if the parameter tsub(c)/t (tsub(c) is the collision time, t-the cosmological time) is zero. It is also shown that in the limit tsub(c)/t→0 the collision integral for a relativistic plasma is identical to the well known Belyaev-Budker integral. At large limiting distances the collision integral does not contain divergences and hence after substitutuion of Gm2 for e2 the collision integral for a nonrelativistic plasma can be applied to a neutral gas of gravitating particles