New York Times, April 30, 2001

Scientists Find Big Bang Evidence

WASHINGTON (AP) - Key elements of theories about how the universe expanded and developed after the Big Bang have been confirmed by data from high-flying balloons and from instruments operating in Antarctica, scientists say.

The instruments, looking deep into the universe, were able to detect minute ripples and distortions in energy patterns within the cosmic microwave background, a faint glow left over from the immense heat of the Big Bang.

Readings from the Degree Angular Scale Interferometer at the Center for Astrophysical Research in Antarctica show tiny distortions in the distribution of matter and variations in temperature just moments after the Big Bang.

A concept, called the inflation theory, holds that these irregularities, enlarging over time, led to the formation of all the big structures in the universe - galaxies, stars and planets.

The new findings, said John Carlstrom, an astronomy professor at the University of Chicago and head of the DASI team, lend strong support to the inflation theory.

``It's always been theoretically compelling,'' said Carlstrom. ``Now it's on very solid experimental ground.''

Carlstrom and his team presented the research Sunday at the spring meeting of the American Physical Society.

The DASI experiment could detect ripples of temperature differences at a time when the universe was about 400,000 years old. The universe is thought to be about 14 billion years old. The inflation theory predicts that the temperature differences would show up as three peaks that become progressively fainter with time. Carlstrom said DASI detected two peaks and suggestions of a third.

Researchers believe the data also support the idea that ordinary matter, of which planets, stars and even people are made, accounts for only about 4.5 percent of the universe's total mass. The rest of the energy in the universe is attributed to cold dark matter, which cannot be easily detected, and to a force called ``dark energy,'' which is thought to be causing galaxies to separate at a faster and faster rate.

Other experimenters, using instruments boosted up to 120,000 feet by balloons detected variations to within 100 millionths of a degree in the cosmic microwave background radiation temperature.

The data, from a project called Balloon Observations of Millimetric Extragalactic Radiation and Geophysics, were gathered in 1998. The data provide more detail for cosmic microwave background temperature data first obtained by a satellite in 1991.

Data from the experiments support the notion that the universe is flat and not curved, an idea that would affect the path taken by light streaking across time and space.

File Date: 5.01.01

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