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FM radio gives away aliens
Posted on Thursday, January 18, 2007 (CST) by Thoth
 If aliens tens of light-years away have radar and FM radio, we may finally be able to hear them. Scientists say piggybacking detection software onto new radio telescopes designed primarily to observe the early universe could allow astronomers to eavesdrop on everyday sounds from distant, Earth-like civilisations.
"The key is to really identify something that looks suspicious and follow up on it," says Avi Loeb, a professor of astronomy at the Harvard-Smithsonian Center for Astrophysics.
Loeb collaborated on the idea with colleague and astrophysicist Professor Matias Zaldarriaga. Until now, searches for extraterrestrial life have relied on conventional observatories, which were built to pick up high-frequency radio waves.
But these would probably be deliberately sent across space as a beacon.
Monitoring these signals
has allowed astronomers to record radiation emitting from galaxies,
quasars, black holes, stars and other cosmic objects, while avoiding
interference from low-frequency signals generated on Earth by radar,
television and FM radio.
But what if aliens have radio and TV like us? Could we listen in?
Just as you can't hear AM
radio channels on an FM receiver, it's impossible to hear low-frequency
signals using high-frequency receivers.
It hasn't ever made sense to build a radio observatory able to scan the cosmos for low-frequency signals, until now.
New telescope
Such facilities, such as
the Low Frequency Demonstrator of the Mileura Wide-Field Array in
Australia, are now under construction to look back into time and space
and map the faint radio glow of cosmic hydrogen left over from the Big
Bang.
"It will tell us about how
the universe evolved from being filled with a diffuse cloud of gas to
containing discrete objects, [and] allow us to test theories of how
that process occurred," says Ed Turner, professor of astrophysical
sciences at Princeton University.
It turns out that the
radiation from distant cosmic hydrogen has the same frequency as radar,
television and FM radio broadcasts on Earth.
Loeb and Zaldarriaga
propose writing special code into the hydrogen-observing software to
also look for artificially generated radiation that could be leaking
from an alien civilisation.
Such radio signals operate in a narrow band in a way that differs from natural radiation coming from molecules.
If the radio waves were coming from a planet that was revolving around a sun, the signals would also appear to shift lightly.
Loeb and Zaldarriaga
calculated that a facility such as the Low Frequency Demonstrator could
detect Earth-like radio waves from 30 light-years away, a distance that
encompasses about 1000 of the nearest stars.
A larger facility could theoretically detect signals from 1500 light-years away, a distance that includes 100 million stars.
But just because the software picks up something suspicious doesn't mean it will have found another civilisation.
It's possible that the
observatory will record radio signals that appear to be coming from
deep space, but in fact are Earth-generated waves that have bounced off
the Moon or have come from an unknown satellite.
"They could see a lot of
false positives that are actually due to terrestrial sources," says
Turner. "They will have to do a significant amount of work to reject
those."
Another challenge will be in sifting through the huge of amounts of data in search of the artificial signal.
"How much is it going to cost to adequately process the data coming out of these telescopes?" says Turner.
And what if, in the end, the signal is coming from deep space?
According to Loeb, the brightest signals on Earth are generated by military radars.
"There is a cautionary
remark," says Loeb. "The brightest civilisations out there could be
militant." In that case, "we don't want to signal ourselves".
Copyright: ABC
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Re: FM radio gives away aliens
by infinity on Friday, January 26, 2007 (CST)
(User Info | Send a Message | Journal) | 1. That makes the earth the loudest and most boorish of all planets known.
2. They don't.
3. Its of some other form of higher evolutionary forms though some may be given to anger.
0. Perhaps they know how to insulate themselves from earthly noise! I am yet to learn to do that vis a vis the loudest boors on earth, though its not merely sound waves but other things that define loud and boorish! |
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