Word: supernova
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Dates: during 2000-2009
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...rather, nobody had got enough data. Back in 1997, astronomers Mark Phillips of the Space Telescope Science Institute and Ron Gilliland of the Carnegie Institute of Washington had used the Hubble Space Telescope to spot a distant supernova designated SN 1997ff and, with the help of Peter Nugent, a Lawrence Berkeley astronomer on Perlmutter's team, had determined its speed of recession from Earth. Nugent couldn't figure out the distance, though: determining the brightness of a Type Ia calls for not just one but several measurements, spread over time...
...rival team, Riess knew of the discovery, but he learned soon afterward that other Hubble photos had also caught the supernova, completely by chance. So one day last summer, he recalls, "I called Peter and began fishing around for information. I guess I wasn't especially cagey. He said almost right away, 'Are you asking about 1997ff...
Rather than try to scoop each other, the friendly rivals decided to cooperate--and soon realized they had stumbled onto something truly astonishing. The new supernova, some 50% closer to the beginning of the universe than any supernova known before, was far brighter than had been predicted. That neatly eliminated the idea of dust, since a more distant star should have been even more dust-dimmed than nearer ones. But the level of brightness also signaled that this supernova was shining when the expansion of the cosmos was still slowing down. "Usually," says Riess, "we see weird things...
...could have been flattened purely by matter--but the new discoveries prove that ordinary matter and exotic particles add up to only about 35% of what you would need. Ergo, the extra curvature must come from some unseen energy--just about the amount, it turns out, suggested by the supernova observations. "I was highly dubious about dark energy based only on supernovas," says Princeton astrophysicist Edwin Turner (no relation to Michael, though the two often refer to each other as "my evil twin"). "This makes me take dark energy more seriously...
...case, new tests of these bizarre ideas will not be too long in coming. Next week a satellite will launch from Cape Canaveral to make the most sensitive observations ever of the cosmic background radiation. Supernova watchers, meanwhile, are lobbying NASA for a dedicated telescope so they won't have to queue up for time on the badly oversubscribed Hubble. And lower-tech telescopes and microwave detectors, both on the ground and lofted into the air aboard balloons, will continue to refine their measurements...