|News from PRINCETON UNIVERSITY
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For immediate release: Feb. 11, 2003
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Satellite produces dramatically sharp 'baby picture' of the universe
Results from NASA/Princeton partnership herald 'a
turning point for cosmology'
PRINCETON, N.J. -- NASA announced Tuesday that a satellite built in
partnership with Princeton scientists has captured a high-resolution
snapshot of the universe in its infancy and produced dramatic insights
into astronomy and physics.
Answers to longstanding questions about the age, composition and evolution
of the universe snapped into sharper focus with the arrival of the data,
which came from a yearlong observation of remnants of light from the
big bang itself.
"We have a map of the earliest light of the universe that is complete,
and it is stunning to look at," said Princeton physicist Lyman Page.
The space agency also announced that it has named the satellite that
collected the data in honor of Princeton physicist David Wilkinson,
who was a founding member of the project team and who died in September
2002. The Wilkinson Microwave Anisotropy Probe measures slight ripples
-- or anisotropies -- in the big-bang afterglow that suffuses the universe.
Among the most surprising results is the discovery that the first stars
formed just 200 million years after the big bang, sooner than previously
thought. Scientists had thought that the first stars formed when the
universe was 800 million years old.
Other implications arising from the data include:
- A dramatically sharper measure of the age of the universe -- 13.7
billion years, plus or minus .2 billion years. That margin of error
is no more than the length of time dinosaurs roamed the earth; previous
estimates had uncertainties many times larger.
- A refined estimate of how much matter exists in the universe and
strong evidence that the universe is dominated by some form of "dark
energy" that is tearing it apart. According to the project scientists,
the universe consists of 4 percent ordinary matter, 23 percent dark
matter of unknown form and 73 percent dark energy. Some previous studies
had suggested more matter and less dark energy.
- A revised and more complex picture of the first microseconds of
the big bang, when the universe appears to have undergone a period
of hyperfast expansion called inflation.
"These numbers represent a milestone in how we view our universe,"
Anne Kinney, NASA director for astronomy and physics, said in the space
agency's news release. "This is a true turning point for cosmology."
"The really remarkable thing is that it all fits," said David Spergel,
a Princeton astrophysicist and a participant in the project. The data
tie together many previous observations from the Hubble Space Telescope
and other sources, essentially completing the basic picture of how the
universe began, he said.
"We have now answered many of the questions that have driven the field
for the past few decades," said Spergel. "How old is the universe? How
much matter is in it? How fast is it expanding? And now we're getting
to address a new set of questions: How did the first stars form? What
are the properties of the dark energy that makes up most of the energy
in the universe?"
The light measured by the satellite is known as the cosmic microwave
background. It is energy that was trapped in the hot gasses of the early
universe and was suddenly released at a point 380,000 years after the
big bang. This light, which has been spreading through the universe
ever since, contains extremely subtle fluctuations that reveal the physical
properties of the cloud from which it emerged.
Today this radiation, which began at nearly 4,000 degrees Celsius,
imparts to the universe a background temperature of just 2.73 degrees
above absolute zero. The Wilkinson satellite measured fluctuations in
that temperature of just millionths of a degree, as well as other equally
The results are a first pass at analyzing data that are expected to
emerge more fully over the next three years. The satellite, launched
in June 2001, occupies a unique point in space 1 million miles from
Earth where it orbits the sun and maintains a straight line between
the sun, Earth and satellite. This vantage point, four times farther
away than the moon, offers an exceptionally quiet place to observe the
The satellite mission is a partnership between NASA's Goddard Space
Flight Center in Greenbelt, Md., and Princeton, with additional collaborators
at Brown University, the University of British Columbia, the University
of Chicago and the University of California-Los Angeles. NASA scientist
Charles Bennett is the project leader.
"The whole group is just a fantastic team," said Page, who attributed
the mission's success to the sustained and close-knit collaboration
between the scientists and the support of many technical specialists
at NASA and Princeton.
For Wilkinson, the project was the last in a series of increasingly
refined measurements of the cosmic microwave background that he had
been making for more than 30 years. NASA's decision to name the satellite
after him could not be more fitting, said Page. "It's the perfect tribute
to his leadership of the field for so many years."
Other team members at Princeton include senior research staff scientist
Norman Jarosik, postdoctoral researchers Christopher Barnes, Michael
Nolta, Eiichiro Komatsu and Licia Verde, and graduate student Hiranya
Peiris. Technicians in the University's physics machine shop built several
key components of the detectors.
For those involved, the announcement of results is a long-awaited moment.
"It was very challenging, but it also is fun to know that things that
I worked on and screws that I tightened are now a million miles away
and are working," said Jarosik, who designed the main parts of the detectors.
"I just love the kind of things you can tell by looking at the sky,"
said Jarosik. "This light is up there; it's there for anyone who can
build a good enough instrument to look at it."
The Wilkinson satellite is expected to collect data for another three
years and could function for twice that long. In the meantime, scientists
at Princeton already are planning new ground-based observations that
will add further clarity to the cosmic microwave background picture.
Note: further information and images are available from NASA at http://www.gsfc.nasa.gov/topstory/2003/0206mapresults.html.