Kate Wong Scientific American
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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