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Search For Aliens Needs To Change Tactics.

E.T. may be phoning us, but we've been listening the wrong way.

That's what Gregory Benford, a physicist at the University of California Irvine and science fiction author, thinks. And he wants to gather a whole lot of amateurs to do it right - and possibly find evidence of alien life.

Benford, his brother James and nephew Dominic recently published a study outlining their idea of how to find alien life and why traditional radio astronomy might not be up to it.

The search for extra-terrestrial intelligence, or SETI, projects, have always looked for radio signals from alien civilizations. Those signals, it is thought, as should be powerful, continuous, with an obvious artificial signature, perhaps a series of numbers.

But Benford thinks that's the wrong way to go if you want to find aliens. Aliens won't send out a continuous signal, but a pulsed one, in short bursts. "It's just not cost-effective," he said. "By many orders of magnitude it's cheaper to do broadband."

That's where the amateurs come in. There are many people who do amateur radio astronomy, and they could watch the sky, sending the raw data to scientists who could analyze it. A similar idea is used in the SETI@Home project, where people donate computer time on their desktops to analyzing signals from space and send the results back.

The reason is simple: calling across interstellar distances is expensive. Signals take energy to make, and if you send one that broadcasts constantly then it will use up a lot. An alien civilization won't spend that much energy when it can do the same thing for less.

And the transmission has to be deliberate; contrary to popular myth, television and radio transmissions don't propagate very far. Not only are the frequencies not optimal for long-range transmissions, but the amount of power they use is relatively small for each individual channel. "It would just look like noise," Benford said. "And it wouldn't even be heard a few light years away." So E.T. isn't watching old episodes of "I Love Lucy."

So if you want to hear aliens, then, the answer is to look for a powerful, short signal, and see if it is repeated. Humans, he noted, have adopted broadband signaling for the same reason in cell phones and Wi-Fi connections.

Most of the time when astronomers scan the sky at radio wavelengths, the software and hardware they use "smoothes out" the signal. That way, scientists can see what a "normal" patch of sky looks like at a given wavelength. It's a good method for finding big, powerful objects like black holes, that blast out lots of energy over long periods. It's also good for getting an idea of what the sky "looks" like in the radio band. "A whole lot of the radio astronomy out there is mapping programs," Benford said.

In fact, some natural phenomena were first mistaken for alien signals when they were discovered. Pulsars, for instance, are rapidly rotating neutron stars that fire out strong radio signals. The first was called "LGM-1" for "Little Green Men."

But if an alien civilization is transmitting, those methods won't pick up the signal at all, and even if they did, the "noise" would be smoothed out, removing a lot of the information in the signal.

Benford says there are a number of signals that have been picked up over the years that could be candidates for alien life. One was the "Wow" signal, detected at Ohio State University in 1977. The signal wasn't heard again, but it was at the right frequency - 1420 megahertz - which is important because it can travel long distances and not get blocked by interstellar dust. Many scientists think that if aliens are transmitting, that frequency, or something close to it, is what will be used. The signal also came from the right direction, near the center of our galaxy, where there are more stars and thus more likely to be aliens.

One of the things amateurs can do, which professional radio telescopes can't, is watch large portions of the sky for a long time. It's similar to how most new comets are found - almost all have been picked up by amateurs with relatively small telescopes.

In radio astronomy, Benford says, most professional telescopes focus on small areas and narrow frequency, and they just aren't designed for hearing broadband signals.

Benford is also confident that if we listen the right way, we are likely to find another civilization out there. "The numbers tell us that there are two possibilities, either one civilization or lots of them," he said. Given how many stars and planets there are in the galaxy, it isn't likely that the number of alien civilizations is so small that none of them decides to transmit.

"If we find one it will be the most significant finding of this century." he said. "SETI is the only science that is doing so much research for a single data point."
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Publication:International Business Times - US ed.
Date:Jul 23, 2010
Words:828
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