Eavesdropping on the Universe (Forwarded)

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For Release: Monday, January 8, 2007

Release No.: 07-01

Eavesdropping on the Universe

Seattle, WA -- Astronomers have proposed an improved method of searching
for intelligent extraterrestrial life using instruments like one now under
construction in Australia. The Low Frequency Demonstrator (LFD) of the
Mileura Wide-Field Array (MWA), a facility for radio astronomy,
theoretically could detect Earth-like civilizations around any of the
1,000 nearest stars.

"Soon, we may be eavesdropping on signals from Galactic civilizations,"
says theorist Avi Loeb of the Harvard-Smithsonian Center for Astrophysics
(CfA). "This is the first time in history that humans will be capable of
finding a civilization like ours among the stars."

Loeb will present his findings on Wednesday, January 10, in a press
conference at the American Astronomical Society meeting in Seattle, Wash.

Previous SETI programs would not have detected an Earth-like civilization.
The searches often looked for beacon-like signals deliberately beamed
across space. Such beacons may not exist. Also, most radio SETI projects
examined frequencies higher than 1 Gigahertz in order to avoid
interference from both Earth-based and natural cosmic sources.

Instead of looking for deliberate broadcasts, Loeb and his co-author
Matias Zaldarriaga (CfA) suggest looking for accidental leakage from an
alien civilization. They point out that the new MWA-LFD, which is designed
to study frequencies of 80-300 Megahertz, will pick up the same
frequencies used by Earth technologies. On Earth, military radars are the
most powerful broadcast sources, followed by television and FM radio. If
similar broadcast sources exist on other planets, facilities like MWA-LFD
might detect them.

"The MWA-LFD is a science instrument intended to study the distant, young
universe," explained Zaldarriaga. "But by piggybacking onto its normal
observations, SETI researchers could use it to look for E.T.
civilizations."

A SETI program at the MWA-LFD would complement other SETI projects. It
will observe a larger area of the sky over a longer period of time and in
a different frequency range.

Loeb and Zaldarriaga calculate that by staring at the sky for a month, the
MWA-LFD could detect Earth-like radio signals from a distance of up to 30
light-years, which would encompass approximately 1,000 stars. More
powerful broadcasts could be detected to even greater distances. Future
observatories like the Square Kilometer Array could detect Earth-like
broadcasts from 10 times farther away, which would encompass 100 million
stars.

If alien broadcasts were detected, additional observations could measure
characteristics of the source planet, such as how fast it rotates or how
long its year is. By combining that information with knowledge of the
parent star, astronomers could estimate the temperature on the planet's
surface to assess whether it may have liquid water and life as we know it.

The MWA-LFD is a radio telescope designed to detect and characterize
highly redshifted 21-centimeter emission from hydrogen molecules in the
early universe. Its key scientific goal is to create a three-dimensional
map of ionized "bubbles" that formed as the first quasars and galaxies
flooded space with ultraviolet light billions of years ago.

The paper describing these findings has been accepted for publication in
the Journal of Cosmology and Astroparticle Physics and is available online
at
http://arxiv.org/abs/astro-ph/0610377

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for
Astrophysics (CfA) is a joint collaboration between the Smithsonian
Astrophysical Observatory and the Harvard College Observatory. CfA
scientists, organized into six research divisions, study the origin,
evolution and ultimate fate of the universe.

Note to editors: Images to accompany this release are online at
http://www.cfa.harvard.edu/press/pr0701image.html