Eliminating the `flatness problem' with the use of Type Ia supernova data

Recent measurements of the cosmological constant or cosmic vacuum in Type Ia SN observations (Riess et al.1998, Perlmutter et al. 1999) imply that $\Omega (t)$ is exactly unity or nearly unity at any epoch of cosmic evolution. No fine tuning is needed to describe this phenomenon with the standard cosmological model based on the Type Ia SN data. A time-independent symmetry relation between vacuum and matter is basically behind the observed near-parabolic expansion.