A new measurement from SDSS-III BOSS reaches twice as far into the past as previous direct measurements of the expansion rate (illustrated by the red dot on the left-hand side). The expansion rate of the universe was slowing down 10 billion years ago, but started to speed up due to the influence of dark energy 6 billion years ago. // Illustration by Z. Rostomian (LBNL)/N. Ross & BOSS Lyman-alpha team (LBNL)