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Sky Survey Tells Story of Expanding Universe

Sky Survey Telescope
Sloan Sky Survey

Early in the history of the universe -- about three billion years after the Big Bang -- the expansion of the universe was slowing down.  Today, it's speeding up at a faster and faster pace. University of Utah astronomer Kyle Dawson is part of a group that's been studying the early universe by looking at how light from quasars affected hydrogen atoms in interstellar space.  The project is part of the Sloan Digital Sky Survey, which Dawson says gives them the very sophisticated tools to look at lots of objects in the far reaches of space.

"We were planning to look at 160,000 [objects] over the course of five years," Dawson tells KUER, "tens of thousands of these objects each year.    And that's an amazingly challenging technology to build."

The equipment looks at spectral lines from hydrogen atoms to determine what was happening in the universe more than ten billion years ago. Dawson says it's the first observational data to support the idea that the universe slowed its expansion until it reached a tipping point.  After that, dark energy pushed it into its current state.
"Different models for what this dark energy could possibly be," he says, "predict different behavior at the time, three billion years after the Big Bang.  And we're making measurements to constrain different models of that dark energy."
Dawson says the ultimate goal is to understand better what dark energy is and how it works.  Their paper has been submitted to the journal Astronomy and Astrophysics.
More information on the University of Utah science news website

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