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NPR's Richard Harris has our story.
RICHARD HARRIS: Scientists know how the universe got started. First came the Big Bang, which created matter, and that stuff has been spreading out for more than 13 billion years. As it cruises outward the distances between all the galaxies keep getting bigger and bigger.
SAUL PERLMUTTER: But we'd always thought that gravity would be slowing that expansion.
HARRIS: Saul Perlmutter, at the Lawrence Berkeley Lab, wanted to find out just how much gravity was actually putting the brakes on our expanding universe.
PERLMUTTER: We didn't know whether there was enough stuff in the universe to slow it to the point that it would come to a halt and perhaps someday collapse.
HARRIS: So in the 1980s, Perlmutter set out to figure out whether the universe would collapse and end with the bang, or just keep expanding forever and end with a whimper. He did that by seeking out distant supernovas, exploding stars, to see what the universe was doing billions of years ago. And finally, after 10 years of searching, Perlmutter came up with an answer so bizarre he wasn't at first sure whether to believe it.
PERLMUTTER: We thought we were finding out how much the universe was slowing down, and whether it was slowing down enough to come to a halt. And, of course, the answer was that it's not slowing down enough to come to a halt. In fact, it's not slowing down at all. It's speeding up.
HARRIS: Speeding up - how could that be? Matter in the universe was supposed to be coasting since the Big Bang, but not so. Somehow or other it was picking up speed, accelerating.
PERLMUTTER: And this was, of course, a big shock.
HARRIS: Borderline unbelievable, but as luck would have it, Perlmutter and his colleagues weren't the only team probing this question. A second team was also on the case, including Adam Riess, now at Johns Hopkins University, and Brian Schmidt, an American, now working in Australia.
ROBERT KIRSCHNER: Well, these are my children.
(SOUNDBITE OF LAUGHTER)
HARRIS: Robert Kirshner at Harvard is speaking here in terms of his academic progeny.
KIRSCHNER: Brian Schmidt and Adam Riess were both graduates students with me, working on supernovae and working on using supernovae to measure cosmic distances.
HARRIS: And, as Kirschner tells a story, one day Schmidt came to him and said he wanted to track down distant supernova and try to answer the same kinds of question that Saul Perlmutter's team was after. He would need to write new software to pick through telescope images and identify those rare supernovas.
KIRSCHNER: And I said, well, these other guys have been working on it for five years - three people - that's 15 years. He said yeah, yeah, I could do it in a month. So...
(SOUNDBITE OF LAUGHTER)
KIRSCHNER: He did, too. It was terrible software. It had crashed all the time and, you know, gave false results some of the time. But he really did whip it together very quickly.
HARRIS: Something weird is at work here driving that acceleration. Exactly what this is nobody can say, but they call it dark energy. And Kirschner says it seemingly makes up 75 percent of the universe.
KIRSCHNER: The simplest kind of dark energy would be everywhere. And so that means it would be present here on the earth. If we could figure out a smart way to detect its presence in a physics laboratory, that would be fantastic.
HARRIS: Richard Harris, NPR News.
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