'We May Be Able to Watch Dark Energy Turn On': Unprecedented Sky Survey
'We May Be Able to Watch Dark Energy Turn On': Unprecedented Sky Survey
Sep. 3, 2013 — Moonless nights outside the Cerro Tololo astronomical observatory in Chile are so dark that when you look down, you can't see your feet.
"You can't see your hands," said David Gerdes, physics professor at the University of Michigan. "But you can hold them up to the sky and see a hand-shaped hole with no stars in it. It's really incredible."
From this site in the Andes over the next five years, an international team will map one-eighth of the sky in unprecedented detail -- aiming to make a time lapse of the past 8 billion years of a slice of the universe. Through the Dark Energy Survey, which began Aug. 31, more than 200 researchers from 25 institutions, including U-M, will search for answers to a fundamental question about the cosmos: Why is its expansion speeding up?
The leading theory points to a mysterious force dubbed dark energy. The new survey won't be able to detect that directly, but the researchers hope to learn insights about its nature by examining the structure of the universe. They'll image some 100,000 galaxy clusters and 3,000 supernovae, as well as measure how light bends through space and time.
All these objects they'll observe, and indeed, all visible matter, make up just a small fraction of the universe. The rest -- roughly 96 percent -- is dark energy and dark matter. Dark matter is an invisible substance that scientists deduce exists because of its effects on visible matter. And dark energy, Gerdes describes, is the smooth energy density of empty space.
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http://www.sciencedaily.com/releases/2013/09/130903151759.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily%2Fspace_time+%28ScienceDaily%3A+Space+%26+Time+News%29
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