Very small scale anisotropies of the microwave background

Among these predictions are proton decay, the existence of non-baryonic matter (to explain the very small or zero spatial curvature of the Universe), and a set of predictions about the properties of density perturbations in the material content of the Universe. It is that last set of predictions, ones we may be able to test with astronomical observations, which are of concern here. New theories of the very early Universe provide an realistic source for small amplitude perturbations in density--quantum fluctuations. Further, these theories permit us to calculate, at least roughly, the relevant amplitudes Δrho/rho at any given epoch in the history of the Universe. Thus, unlike earlier versions of the Big Bang model, the new inflationary models provide an explanation for density perturbations rather than building them in as initial conditions. GUTs also predict that density perturbations will be adiabatic, rather than isothermal; that is that they will have a constant baryon to photon ratio. Finally, inflation suggests a scale-invariant spectrum for the perturbations, which leads to a mass spectrum of the following sort: Δrho/rho proportional to M/sup -2/3/. The importance of these new theories in cosmology makes any attempt to confirm such predictions worthwhile--even if the attempt involves some messy astrophysical details