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NASA Science News for February 11, 2003

The Oldest Light in the Universe
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A NASA satellite has captured the sharpest-ever picture of the
afterglow of the big bang. 

Feb. 11, 2003:  NASA today released the best "baby picture" of the
Universe ever taken; the image contains such stunning detail that it
may be one of the most important scientific results of recent years.
Scientists used NASA's Wilkinson Microwave Anisotropy Probe (WMAP) to
capture the new cosmic portrait, which reveals the afterglow of the
big bang, a.k.a. the cosmic microwave background. 

"We've captured the infant universe in sharp focus, and from this
portrait we can now describe the universe with unprecedented
accuracy," said Dr. Charles L. Bennett of the Goddard Space Flight
Center (GSFC) and the WMAP Principal Investigator. "The data are
solid, a real gold mine," he said. 

One of the biggest surprises revealed in the data is the first
generation of stars to shine in the universe first ignited only 200
million years after the big bang, much earlier than many scientists
had expected. 

In addition, the new portrait precisely pegs the age of the universe
at 13.7 billion years, with a remarkably small one percent margin of
error. 

The WMAP team found that the big bang and Inflation theories continue
to ring true. The contents of the universe include 4 percent atoms
(ordinary matter), 23 percent of an unknown type of dark matter, and
73 percent of a mysterious dark energy. The new measurements even shed 
light on the nature of the dark energy, which acts as a sort of
anti-gravity. 

"These numbers represent a milestone in how we view our universe,"
said Dr. Anne Kinney, NASA director for astronomy and physics. "This
is a true turning point for cosmology." 

The light we see today, as the cosmic microwave background, has
traveled over 13 billion years to reach us. Within this light are
infinitesimal patterns that mark the seeds of what later grew into
clusters of galaxies and the vast structure we see all around us
today. 

Patterns in the big bang afterglow were frozen in place only 380,000
years after the big bang, a number nailed down by this latest
observation. These patterns are tiny temperature differences within
this extraordinarily evenly dispersed microwave light bathing the
universe, which now averages a frigid 2.73 degrees above absolute zero 
temperature. WMAP resolves slight temperature fluctuations, which vary 
by only millionths of a degree. 

Theories about the evolution of the universe make specific predictions 
about the extent of these temperature patterns. Like a detective, the 
WMAP team compared the unique "fingerprint" of patterns imprinted on 
this ancient light with fingerprints predicted by various cosmic 
theories and found a match. 

WMAP will continue to observe the cosmic microwave background for an
additional three years, and its data will reveal new insights into the 
theory of Inflation and the nature of the dark energy. 

"This is a beginning of a new stage in our study of the early
universe," said WMAP team member Prof. David N. Spergel of Princeton
University, N.J. "We can use this portrait not only to predict the
properties of the nearby universe, but can also use it to understand
the first moments of the big bang," he said. 

WMAP is named in honor of David Wilkinson of Princeton University, a
world-renowned cosmologist and WMAP team member who died in September
2002. 

Credits & Contacts
Based on a NASA/Goddard press release 
Responsible NASA official: Ron Koczor 
Production Editor: Dr. Tony Phillips 
Curator: Bryan Walls 
Media Relations: Steve Roy

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