In 1998, measurements of distant supernovae indicated that the expansion of the universe is accelerating, and this was supported by other observations including ground-based CMB observations and large galaxy red-shift surveys. In 1999–2000, the Boomerang and Maxima balloon-borne CMB observations showed that the geometry of the universe is close to flat, then in 2001 the 2dFGRS galaxy red-shift survey estimated the mean matter density around 25–30 percent of critical density.