Title : PR 93-53 South Pole Researchers Observe Early Structure of the
Type : Press Release
NSF Org: OD / LPA
Date : July 15, 1993
File : pr9353
Lynn Simarski, NSF EMBARGOED UNTIL 2:30 P.M.(PDT):
(202) 357-9498 June 10, 1993
NSF PR 93-53
Diana Steele, University of Chicago
Justin Harmon, Princeton University
SOUTH POLE RESEARCHERS
OBSERVE EARLY STRUCTURE OF THE UNIVERSE
Scientists working at the South Pole have discovered
evidence of cosmic structures that formed just one million years
after the universe began. They announced their results June 10
at the American Astronomical Society meeting in Berkeley,
Physicists Mark Dragovan and Jeffrey Peterson, both from
Princeton University, made their observations at the Center for
Astrophysical Research in Antarctica (CARA), operated by the
University of Chicago. CARA is a Science and Technology Center
funded by the National Science Foundation (NSF), and managed
under the U.S. Antarctic Program, which is run by NSF.
Using two specially designed radio telescopes at CARA's
South Pole observatory, the researchers detected small
temperature fluctuations in microwave radiation left over from a
scant one million years after the Big Bang. Scientists believe
that the massive explosion gave birth to the universe 12-20
billion years ago.
The temperature fluctuations suggest the seeds of the
clustered structures that may have evolved into the galaxies seen
today. The fluctuations detected from shortly after the
universe's birth mean that parts of the universe were slightly
denser than others, according to Dragovan. "Although more work
needs to be done to confirm the results, we probably have seen
the beginnings of structure in the universe," he said.
For years, astronomers have searched for slight variations
in the radiation from the early universe. They have sought the
origin of the very "lumpy," or inhomogeneous, distribution of
matter in today's universe--a structure featuring massive
galaxies with billions of stars, separated by vast expanses of
nearly empty space. Until very recently, however, measurements
showed the primal radiation to be perfectly uniform, implying
that its source, the early hot matter, was just as smooth.
The new findings complement measurements announced last year
by other researchers using the Cosmic Background Explorer (COBE)
satellite. COBE's telescope observed irregularities in the
microwave radiation over relatively large patches in the sky,
about seven degrees across.
The two CARA telescopes used at the South Pole during the
southern summer of 1992-93 measure variations on smaller scales.
One, a three-quarter meter telescope developed by Dragovan,
observes regions three degrees across. The larger, one-meter
telescope developed by Peterson "sees" a narrower part of the
sky--about half a degree wide.
The cosmic background radiation the researchers studied is
just 2.7 degrees celsius above absolute zero. Only Dragovan's
telescope detected the tiny temperature variations, discerned at
a level of approximately thirty parts per million.
Although Peterson did not detect variations, he showed that
if variations do exist they must be at levels of less than eight
parts per million, an observation that is difficult for current
theories to explain. "A `fog' or `cosmic mist' of free electrons
may be obscuring our view of the smaller-scale structure of the
universe," Peterson suggested.
The researchers hope to refine these results through future
observations at the Pole. The smaller telescope will be used
over the 1994 Antarctic winter, and a new 2.5 meter telescope
will be built next year to continue the search for temperature
variations and the structures they represent at the smaller
CARA director Doyal Harper, a University of Chicago
astrophysicist, said there are distinct advantages to working as
part of a Science and Technology Center like CARA. "The
scientists and other center personnel can share ideas and
technical and logistical support," he said. "This makes it
possible to conduct complex experiments using state-of-the-art
detectors even in the demanding polar environment." For example,
the radio wave detectors at the Pole had to be cooled nearly to
absolute zero-- difficult enough in a fully-equipped laboratory,
not to mention at a remote outpost.
The advantages of doing astronomy at the South Pole,
however, far outweigh the discomforts. The extremely dry air is
almost completely free of water vapor, which ordinarily obscures
observations of the microwave glow. Also, the same patch of sky
can be observed continuously from the Pole, so a telescope can be
used much more efficiently there than at lower latitudes.
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scientific progress in the United States. NSF accomplishes its
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institutions for research and education in the sciences,
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