RELATIVISTIC PLASMA IN A HOMOGENEOUS COSMOLOGICAL BACKGROUND

The linearized theory of a relativistic plasma in a radiation backgrou nd, proposed recently by Holcomb and Tajima, is extended for a more ge neral background with the metric components being an arbitrary power f unction of time (approximately t(n)). It is noted that the electric fi eld falls off faster and the redshift of the electromagnetic radiation frequency is also greater in a more rapidly expanding background univ erse. The dispersion relation for the transverse vibration of the elec tromagnetic field, however, appears to be independent of the parameter n. The wave equation for the electric field is solved for a de Sitter background also.