Spottiness in the large-scale structure of the microwave background

Abstract

Barrow et al.¹ have recently considered the large-scale temperature variation (ΔT/T) distribution of the microwave background in the open universe. Interest in this topic has been stimulated by new observations from balloons and the satellite Prognoz. Barrow et al.¹ seem to have misunderstood the theory that we have developed^2–4 and arrived at conclusions directly contradicting our results. Here we argue that the main conclusions reached by Barrow et al.¹—that concerning the relationship between inhomogeneous and the most general homogeneous anisotropic cosmologies, and their other claim that the sky ΔT/T pattern of infinite-wavelength inhomogeneities is a superposition of Bianchi type VII models—are erroneous.