1. Department of Applied Physics and Information Science, University of California, San Diego, La Jolla, California 92093

Abstract

THE observed cosmic microwave background radiation, which has a high degree of spatial isotropy (T/T10^-3) and which closely fits a 2.7 K black body spectrum, is generally claimed to be the strongest piece of evidence in support of hot big bang cosmologies by its proponents (for a recent review see ref. 1). Alternative explanations in terms of the integrated effect of a suitable population of extragalactic radio sources^2–6 have been criticised, essentially on the ground that there is no known population of extragalactic objects with a source density sufficient to explain the observed small-scale isotropy of the microwave background⁷. We report here that the 'surface of last-scattering' of the observed microwave background radiation corresponds to the distribution of dust in galaxies or proto-galaxies with a temperature 110 K at the epoch corresponding to Z 40, and not to a plasma of temperature 3,000 K at an earlier epoch (Z > 1,000), as given by the canonical model of big bang cosmologies. The claim that this radiation lends strong support to hot big bang cosmologies is without foundation.