  The equations of motion are solved analytically for speed and position for
the case of blackbody friction on objects traveling at relativistic speeds with
respect to observers fixed in the frame of the blackbody radiation. Two model
cases are considered, both assume an object which is a perfect absorber of
light, and one of which also assumes that the object maintains a constant rest
mass by emitting photons in a momentum neutral process. The maximum distances
attained for a light sail and a micron-size sand grain are determined under the
assumption that the relevant blackbody source is that of cosmic background
radiation. At a temperature of 3000K, the temperature at the time the universe
became transparent, cosmic background radiation would cause a significant decay
of speed fluctuations in dust clouds.
