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Will the Universe's Big Bang End in a 'Big Crunch'?

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In their quest to answer the biggest questions about the universe, scientists are turning to a 1,700-pound satellite taking shape here at NASA's Goddard Space Flight Center.

The $88-million spacecraft is designed to make the most precise all-sky maps yet of tiny changes in the afterglow from the fireball that, scientists say, formed the universe. The changes, researchers say, constitute a cosmic code that will help them answer the ultimate question: Will the universe expand forever or slow, contract, and collapse in the "big crunch"?

Known as cosmic microwave background radiation, the afterglow first picked up as a "hiss" in 1964 carries details on key features of the cosmos, such as the nature and density of its matter, its evolution, and its expansion rate.

Competing notions about how the universe evolved and what its future holds depend on those details, explains Charles Bennett, the lead scientist on the satellite project, called the Microwave Anisotropy Probe (MAP).

"Basically, Joe Blow comes up with a model of cosmology. He says: I like this kind of matter and this much of it. He can tell you exactly what fluctuations you should see in the cosmic background radiation," Dr. Bennett says. "This means that the cosmic background radiation becomes an incredibly powerful tool" for testing theories. "That's why people are so excited" about the mission, adds George Smoot III, an astrophysicist at the Lawrence Berkeley National Laboratory in Berkeley, Calif. "Either we will understand the universe, or we'll have to come up with new ideas" if the satellite's data fail to match theories' predictions.

The cosmic microwave background presents a picture of the universe when it was only 300,000 years old. It has provided some of the most convincing evidence yet that the universe exploded outward from an extremely dense, hot spot in space some 15 billion years ago. In 1964, Bell Laboratory researchers Arno Penzias and Robert Wilson discovered the radiation while testing microwave relay antennas designed for long-distance telephone service. They found the radiation to be uniform in all directions.


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