Position-Space Description of the Cosmic Microwave Background and Its Temperature Correlation Function

We suggest that the cosmic microwave background (CMB) temperature correlation function $C\left(\theta \right)$ as a function of angle provides a direct connection between experimental data and the fundamental cosmological quantities. The evolution of inhomogeneities in the prerecombination universe is studied using Green’s functions in position space. We find that a primordial adiabatic point perturbation propagates as a sharp-edged spherical acoustic wave. Density singularities at its wave fronts create a feature in the CMB correlation function distinguished by a dip at $\theta \approx 1.2°$. Characteristics of the feature are sensitive to the values of cosmological parameters, in particular to the total and the baryon densities.