Effect of quantum conditions in a Friedmann cosmology

Abstract

The observed isotropy of the microwave background and its primordial interpretation has led many to investigate the nature of particle horizons in cosmological models near the initial singularity. The standard Friedmann radiation universe ds²=dt²-λt[dr²+r²(dθ²+sin²θdφ²], λ=constant (1) has a particle horizon at r=2(t/λ)^½ (2) at epoch t. Thus near the singularity t=0, very limited causal communication is possible between different parts of the universe. The observed isotropy of the microwave background cannot be understood in such a model except as arising from artificially imposed initial conditions, Misner has sought to remedy the situation by looking for solutions of the classical Einstein equations very different from the Robertson-Walker form (to which that given by equation 1 above belongs). These solutions permit unlimited communication near t=0.