14 DAY TRIAL // Efforts to search for extraterrestrial intelligence have been going on for decades, and the most famous program is SETI (Search for Extraterrestrial Intelligence), whose generic approach is to survey the sky, through radiotelescopes, to detect the transmissions from a civilization on a distant planet.
The OSU SETI program gained fame on August 15, 1977 when Jerry Ehman, a project volunteer, witnessed a startlingly strong signal received by the telescope. He quickly circled the indication on a printout and scribbled the phrase "Wow!" in the margin. This signal, dubbed the Wow! signal, is considered by some to be the most likely candidate from an artificial, extraterrestrial source ever discovered, but it has not been detected again in several additional searches.
Could it be because we're not paying attention anymore?
For instance, gamma-ray telescopes are designed to detect the highest-energy particles of light: photons from exploding stars and the like. "There are 20 to 30 naturally occurring light flashes recorded every second" by gamma-ray telescopes around the world, says astrophysicist Joachim Rose of the University of Leeds in the U.K. The telescope software usually ignores the flashes because it is configured to reject "anything that it doesn't expect," he says.
Now an international team of researchers is proposing to look for flashes from alien laser beams as well using gamma-ray telescopes.
If their ultra-fast, ultra-sensitive cameras are tuned to the proper wavelength, they can detect faint flashes of optical light of the sort that might come from lasers positioned thousands of light-years away.
As a start, he and his colleagues have analyzed about 1400 hours of archival observations collected since 1999 by the 10-meter Cerenkov telescope at the Whipple Observatory in Arizona. The data include observations of 129 sun-like stars in the Milky Way galaxy, which would be obvious places to look for alien life. Intriguingly, the data reveal a flash of light from such a star once every 6 hours on average, the researchers reported this week at a conference at the University of Surrey, U.K. Alas, non-sun-like stars flash at the same frequency.
"Of course, it would have been even more interesting to find a [confirmed] signal, but we didn't see anything," Rose says.
If aliens were using an optical beacon they should to be more precise in their aiming to light up a distant planet, while sending a radio signal can cover a much wider area of a planetary system.
Unfortunately, the optical technique will spot aliens only if they happen to be beaming signals right at Earth.