Visualizing the Beyond

Until recently, we only knew the distances to about two million galaxies. But in April, the documented galactic census exploded to six million, thanks to the biggest-ever 3D map of the universe, produced by the Dark Energy Spectroscopic Instrument (DESI), an experiment based in Kitt Peak, Ariz., funded by the U.S. Dept. of Energy. The DESI map offers clues to the behavior of dark energy, an invisible force believed to be causing the expansion of the universe. Before the DESI map, the accepted model held that expansion had been speeding up over the past 11 billion years; now scientists believe it has waxed and waned. “The [map’s] third dimension takes us back in time,” says DESI Director Michael Levi. It also points to a long-off future in which the universe may contract and collapse.

Correction, Nov. 1
The original version of this story misstated the rate at which the previous model showed the universe was expanding. It was shown to be speeding up, not holding steady.