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This article is from the In-Depth Report Cosmic Inflation and Big Bang Ripples

Antarctic Experiments Back Cosmic Inflation Theory

New data on the early cosmos are providing the strongest evidence yet that our universe underwent an enormous growth spurt shortly after the big bang, according to findings announced yesterday at the American Physical Society meetings in Washington, D.C. This latest support for cosmic inflation theory comes from observations made by two scientific teams using instruments operating from the South Pole.

Inflation theory, first proposed in the early 1980s, predicts that a pattern of tiny temperature differences should exist in the cosmic microwave background (CMB), the afterglow of the big bang. It also predicts that this pattern should exhibit a series of progressively fainter peaks. Experiments conducted in 1992 using NASA's Cosmic Background Explorer provided the first images of the temperature variations, and later observations from other instruments hinted at the presence of a peak. But the new results from the Degree Angular Scale Interferometer (DASI) and the Balloon Observations of Millimetric Extragalactic Radiation and Geophysics (BOOMERANG) project reveal two peaks and strongly suggest the presence of a third one. "With these new data, inflation looks very strong," notes University of Chicago astrophysicist John Carlstrom, leader of the DASI team. "It's always been theoretically compelling. Now it's on very solid experimental ground."

Of particular interest is the ratio of intensity between the first and second peaks, which indicates how much ordinary matter¿the stuff of humans, stars and galaxies¿exists in the universe. According to the data from DASI, it amounts to a mere 4.5 percent of the universe's total mass and energy¿a number that accords well with an estimate made in 1998 based on the amount of the element deuterium produced during the big bang. "The agreement between measures of the amount of ordinary matter is simply stunning," says Michael Turner of the University of Chicago. "The big bang framework and Einstein's general relativity," he adds, "have passed a major new test."

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