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Universe at Least 12.5 Billion Years Old
By Reuters
posted: 02:44 pm ET
07 February 2001
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universe_age_wg_010207 LONDON -- A team of international scientists may have found the answer to a question that has baffled astronomers for centuries: How old is our universe? At least 12.5 billion years old, give or take a few billion years, according to new research published in the science journal Nature Wednesday. Roger Cayrel, of the Paris-Meudon Observatory in France, and his colleagues in Europe, South America and the United States calculated the age of the universe by taking a different approach. Instead of measuring the expansion rate of the universe or the velocities of distant stars, they measured amounts of the radioactive elements thorium and uranium in an ancient star named CS31082-001 using a technique called radioactive cosmochronometry. "The ages of the oldest stars in the galaxy indicate when star formation began and provide a minimum age for the universe," Cayrel said in a study. By their best calculations CS31082-001 is about 12.5 billion years old, with an error factor of about three billion years. In a commentary on the research, Christopher Sneden of the University of Texas in Austin described the study as a major advance in radioactive cosmochronometry. "We may expect to find more examples of such stars, as our survey of the galactic halo with the new generation of very large telescopes is just beginning," he said. "With new discoveries, more age estimates will be found, further nailing down the exact age of the universe."
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