Scientists peering back to the oldest light in the
universe have new evidence for what happened within its
first trillionth of a second, when the universe suddenly
grew from submicroscopic to astronomical size in far less
than a wink of the eye.
Using new data from a NASA satellite, scientists have
the best evidence yet to support this scenario, known as
"inflation." The evidence, from the Wilkinson Microwave
Anisotropy Probe satellite, was gathered during three years
of continuous observations of remnant afterglow light
— cosmic background radiation that lingers, much
cooled, from the universe's energetic beginnings 13.7
billion years ago.
In 2003, NASA announced that the WMAP satellite had
produced a detailed picture of the infant universe by
measuring fluctuations in temperature of the afterglow,
answering many long-standing questions about the universe's
age, composition and development. The WMAP team has built
upon those results with a new measurement of the faint
glare from the afterglow to obtain clues about the
universe's first moments, when the seeds were sown for the
formation of the first stars 400 million years later.
"It amazes me that we can say anything about what
transpired within the first trillionth of a second of the
universe, but we can," said Charles L. Bennett, WMAP
principal investigator and a professor in the
Henry A. Rowland
Department of Physics and Astronomy at Johns Hopkins.
"We have never before been able to understand the infant
universe with such precision. It appears that the infant
universe had the kind of growth spurt that would alarm any
mom or dad."
WMAP results have been submitted to the
Astrophysical Journal and are posted online at
The newly detected pattern, or polarization signal, in
the glare of the afterglow is the weakest cosmological
signal ever detected — less than a hundredth of the
strength of the temperature signal reported three years
"This is brand-new territory," said Princeton
University physicist Lyman Page, a WMAP team member. "We
are quantifying the cosmos in a different way to open up a
new window for understanding the universe in its earliest
Comparing the brightness of broad features to compact
features in the afterglow light (like comparing the heights
of short-distance ripples vs. long-distance waves on a
lake) helps tell the story of the infant universe. One
long-held prediction was that the brightness would be the
same for features of all sizes. In contrast, the simplest
versions of inflation predict that the relative brightness
decreases as the features get smaller. WMAP data are new
evidence for the inflation prediction.
The new WMAP data, combined with other cosmology data,
also support established theories on what has happened to
matter and energy over the past 13.7 billion years since
its inflation, according to the WMAP researchers. The
result is a tightly constrained and consistent picture of
how our universe grew from microscopic quantum fluctuations
to enable the formation of stars, planets and life.
According to this picture, researchers say that only 4
percent of the universe is ordinary familiar atoms; another
22 percent is an as yet unidentified dark matter, and 74
percent is a mysterious dark energy. That dark energy is
now causing another growth spurt for the universe, one
fortunately, they say, more gentle than the one 13.7
billion years ago.
WMAP was launched June 30, 2001, and is now a million
miles from Earth in the direction opposite the sun. It is
able to track temperature fluctuations at levels finer than
a millionth of a degree.
The WMAP team includes researchers at the Goddard
Space Flight Center in Greenbelt, Md.; Johns Hopkins;
Princeton; the Canadian Institute of Theoretical
Astrophysics in Toronto; the University of Texas at Austin;
Cornell University; the University of Chicago; Brown
University; the University of British Columbia; the
University of Pennsylvania; and the University of
California, Los Angeles.