The Evidence Comes Together

Abstract

Two large scale structure surveys catalogue the position and redshift of over 200,000 and 650,000 extra-galactic objects respectively, and in 1998 astronomers announce that the expansion of the Universe is accelerating. The cosmological constant and ‘dark energy’ are (re)introduced to explain this and other observations. By 2003 WMAP has produced the most spectacularly detailed measurements of the anisotropies in the cosmic microwave background from angular scales larger than COBE down to angular scales less than the smallest achieved from the ground. It pins down the values of cosmological constants like the age of the Universe, its density, the Hubble constant, and the percentages of baryonic matter, dark matter and dark energy to a level of accuracy unimagined a few decades ago.