How much has the universe expanded and how quickly? A pair of new analyses yields the most precise answer to that question we've ever had.
So, how much is the universe expanding? 10.8 billion years ago, the universe expanded at a rate of 1% every 44 million years. Or, to put it another way, its expansion outwards measures at 68 km/second per million light years at redshift 2.34, with an accuracy of 2.2 %.
Just what does that all mean? Andreu Font-Ribera, a physicist with Lawrence Berkeley National Laboratory who led one of the studies, explains:
This means if we look back to the universe when it was less than a quarter of its present age, we'd see that a pair of galaxies separated by a million light years would be drifting apart at a velocity of 68 kilometers a second as the universe expands. The uncertainty is plus or minus only a kilometer and a half per second.
The results of the studies — one from Timothée Delubac of the Centre de Saclay and the other from Font-Ribera of the Lawrence Berkeley National Laboratory — were presented were presented at today's American Physical Society meeting. Both of the studies looked at data from the Baryon Oscillation Spectroscopic Survey (which goes by the apt moniker BOSS), using a combination of 150,000 distant quasars and maps of how gas clouds were position around them.
Image: Artist's conception of BOSS taking measurements from distant quasars / Lawrence Berkeley National Laboratory