August 30, 2002

BY NANCY MOFFETT STAFF REPORTER

The University of Chicago will lead a team of scientists in a $16.5 million project to set up a telescope at the South Pole to tease out secrets of "dark energy'' from the depths of the universe, the university announced Thursday.

"One of our main goals is to figure out what the dark energy is," said Bruce Winstein, director of the U. of C.'s Center for Cosmological Physics.

The search for dark energy started only four or five years ago, but understanding it has become a holy grail for physicists and astronomers.

"We think of it as sort of energy pervading the universe,'' said Joe Mohr, professor of astronomy and physics at the University of Illinois at Urbana-Champaign, who also will work on the project.

The radiotelescope will help look back in time to when the universe was very young, to chart when and how fast the massive galaxy clusters formed.

"They started appearing as the universe got older,'' Mohr said, just as "in the springtime, you notice first there are a few dandelions that pop up in your yard and then more and more appear.''

The trick is to pick up "shadows" of the clusters in the microwave background--thought of as the afterglow of the Big Bang--that pervades the universe.

As the microwaves pass through galaxy clusters, a distortion--or shadow--is introduced that can be detected with the telescope, Mohr said. It will produce a cluster map "in exquisite detail,'' he said.

The next and trickier step will be to connect it to the dark energy.

Observations of supernovae, the cosmic microwave background and galaxy clusters "are telling us a consistent story'' that the expansion of the universe is accelerating, Mohr said. "Something we can call dark energy would explain why.''

In a sense, dark energy "has a gravitational repulsion rather than attraction,'' he said.

The telescope will be more than 25 feet in diameter and can map the microwave sky accurate to 10 millionths of a degree Kelvin.

Under a five-year National Science Foundation grant it will be at the NSF South Pole Station.

The U. of C.'s John Carlstrom heads the project, which besides the U. of I. includes scientists from the University of California at Berkeley, Case Western Reserve University and Harvard-Smithsonian Center for Astrophysics.