 |
Scientific News  Physics Astrophysics MICROWAVE IMAGER PROBES UNIVERSE ‘FIRST LIGHT’ TO ANSWER COSMOLOGICAL QUESTIONS. INDEPENDENT EVIDENCE OF INFLATION THEORY.
MICROWAVE IMAGER PROBES UNIVERSE ‘FIRST LIGHT’
TO ANSWER COSMOLOGICAL QUESTIONS. INDEPENDENT EVIDENCE OF INFLATION THEORY.
|
Astronomers operating from a remote plateau
in the Chilean desert have produced the most detailed images ever made of
the oldest light emitted by the universe, providing independent
confirmation of controversial theories about the origin of matter and
energy.
Pushing the limits of available
technology, the Cosmic Background Imager (CBI) funded by the National
Science Foundation (NSF) and California
Institute of Technology (Caltech) detected minute variations in the cosmic
microwave background, the radiation that has traveled to Earth over almost
14 billion years. A map of the fluctuations shows the first tentative
seeds of matter and energy that would later evolve into clusters of
hundreds of galaxies.
The measurements also provide independent
evidence for the long-debated theory of inflation, which states that the
universe underwent a violent expansion in its first micro-moments. After
about 300,000 years it cooled enough to allow the seeds of matter to form
and became "transparent," allowing light to pass through. CBI
observed remnants of that early radiation. The data are also helping
scientists learn more about the repulsive force called "dark energy"
that appears to defy gravity and force the universe to accelerate at an
ever-increasing pace.
"This is basic research at its finest
and most exciting," said NSF Director Rita Colwell. "Each new
image of the early universe refines our model of how it all began. Just as
the universe grows and spreads, humankind's knowledge of our own origins
continues to expand, thanks to the technical expertise and patient
persistence of scientists such as these."
"We have seen, for the first time, the
seeds that gave rise to clusters of galaxies, thus putting theories of
galaxy formation on a firm observational footing," said team leader
Anthony Readhead of Caltech. "These unique high-resolution
observations provide a new set of critical tests of cosmology, and provide
new and independent evidence that the universe is flat and is dominated by
dark matter and dark energy." |
|
The CBI observed the cosmic microwave background, a snapshop of the
universe at 300,000 years old.
Credit: CBI/Caltech/NSF
Larger
version for downloading is here.
File size: 57 kb
The CBI consists of 13 radio antennas located on a plateau at 5,080 meters
(16,700 feet) in Chile's Atacama Desert.
Credit: CBI/Caltech/NSF
Larger
version for downloading is here.
File size: 146 kb |
 Readhead, with Caltech colleagues Steve Padin and
Timothy Pearson and others from Canada, Chile and the United States, generated
the finest measurements to date of the cosmic microwave background. Cosmic
microwave background (CMB) is a record of the first photons that escaped from
the rapidly cooling, coalescing universe about 300,000 years after the cosmic
explosion known as the Big Bang that is commonly believed to have given birth to
the universe.
Data from the CBI on temperature distributions in
the CMB support a modification of the Big Bang theory; that modification is
called inflation theory. Inflation states that the hot plasma of the initial
universe underwent an extreme and rapid expansion in its first 10 -32
second. The variations in temperature measured by the CBI are as small as 10
millionths of a degree.
By plotting the peaks of temperature distribution,
the scientists showed that the precise CBI data are entirely consistent with
inflation and confirm earlier findings by other scientists. In April 2000, an
international team of cosmologists led by Caltech's Andrew Lange announced the
first compelling evidence that the universe is flat-that is, its geometry is
such that parallel lines will neither converge or diverge. Lange's team observed
at a different frequency from CBI, using a high-altitude balloon flown over
Antarctica.
Since then, two other teams -- using independent
methods -- have revealed their analyses of the very faint variations in
temperature among the cosmic microwaves. The four instruments have conducted
precise measurements of parameters that cosmologists have long used to describe
the early universe. Each set of data has offered new clues to the form of the
embryonic plasma and has drawn scientists closer to definitive answers. NSF has
supported the work of all four teams and their instruments, some of them for
more than 15 years.
Five papers on the CBI data were submitted today
to the Astrophysical Journal for publication.
The CBI consists of 13 interferometers mounted on
a 6-meter-diameter platform, operating at frequencies from 26 GHz to 36 GHz.
Located in the driest desert in the world -- the Atacama -- CBI takes advantage
of the low humidity at an altitude of 5,080 meters (16,700 feet). NSF has
supported the CBI research since 1995. The National Council of Science and
Technology of Chile provided the CBI site.
For more information and images, see: http://www.nsf.gov/od/lpa/news/advance/pr0241_images.htm
and http://www.astro.caltech.edu/~tjp/CBI/
Media contact: Amber
Jones, (703) 292-8070, aljones@nsf.gov
Program contact: Morris
Aizenman, 703-292-8807, maizenma@nsf.gov
Source of the given news and the copyrights
belong to a National
Science Foundation
Publishing date: June 5, 2002
Back
|  |
