Supernovae show that cosmic expansion is accelerating

Two teams, the Supernova Cosmology Project led by Saul Perlmutter and the High-z Supernova Search Team led by Brian Schmidt and Adam Riess, measured the brightness of distant Type Ia supernovae and found them dimmer than expected. The explanation was that the expansion of the universe is speeding up rather than slowing under gravity, driven by a mysterious dark energy that makes up about 70 per cent of the cosmos. The announcement in 1998 overturned previous assumptions and earned the three leaders the 2011 Nobel Prize in Physics. The nature of dark energy remains unknown.

Open on the timeline