... We start investigating the results from a non-magnetized (isotropic) plasma, before including the external magnetic field so important for space physics. ... propagating above the electron plasma frequency, w(pe) (reflection point for the waves) . note that, for very high frequencies, both phase and group velocities are equal to light velocity c, and we have electromagnetic wave in free space: even the electrons are unable to respond to the rapidly oscillating electric field! . ...