Thomson scattering of supernova radiation and the expansion history of the Universe

The observed distances to SNe Ia objects are corrected for the Thomson scattering of their radiation by free electrons. An independent calculation of the density of free electrons contained in a dark intergalactic plasma is adequate for close agreement of the corrected distances with predictions of the luminosity-distance relation. Hence the apparent dimming of SNe Ia objects can be understood without recourse to cosmic acceleration and cosmic jerk.