By Ron Cowen
Ever since 1998, Robert Caldwell has been obsessed with something dark and repulsive. He spends nearly every waking moment trying to comprehend a mysterious entity that may be undermining gravity and pulling everything apart, making the universe expand at a faster and faster rate. This presumed force, sometimes called dark energy, might ultimately rip apart every object in the cosmos, from the tiniest of atoms to gargantuan clusters of galaxies (SN: 2/28/04, p. 132: Available to subscribers at Wrenching Findings: Homing in on dark energy). “It’s both fascinating and terrifying,” says Caldwell, a cosmologist at Dartmouth College in Hanover, N.H.
Caldwell has partners in his obsession, among them other theorists and the astronomers who dropped the bombshell about cosmic acceleration onto the scientific community 6 years ago. That’s when two studies of distant exploding stars first revealed that the universe is accelerating its rate of expansion—exactly the opposite of what had been expected. The mutual gravity of all the matter in the cosmos ought to be slowing down the expansion that began with the Big Bang. The new observations led the teams to propose that there was something previously unimagined pushing everything away from everything else.