50 Years of Seeking E.T. It's been almost 50 years since scientists first came up with the idea of looking for radio signals from extraterrestrial civilizations - and although there have been a couple of curious blips, we haven't yet definitively heard E.T.'s cosmic call. Now the experts in the search for extraterrestrial intelligence, or SETI, are wondering whether we've been looking in the wrong places for the wrong kinds of signals.
Or maybe we just haven't been looking long enough.
All of those possibilities are considered in "Confessions of an Alien Hunter," a new book from Seth Shostak, the SETI Institute's senior astronomer.
<snip>
Over the decades, the strategy for SETI has by necessity been dictated by a cosmic Golden Rule: We look for communication in the channels that we use to communicate. A generation ago, that might have been the analog television signals that carried "I Love Lucy" out to the cosmos. Today, Drake speculates that the aliens might be transmitting digitally, with lasers instead of monster radio antennas.
During a weekend talk in Seattle, Drake pointed out that the just-completed National Ignition Facility can focus the light of 192 lasers to create a pulse that lasts just a few nanoseconds but far outshines the sun. "Those lasers can make pulses of light which are visible to very small telescopes all across the galaxy," he noted.
Shostak theorizes that E.T. might have two types of transmitters going: one that flashes such pulses of light toward a long list of target planets that might be habitable - including us - and another "low-power, omnidirectional broadcast that tells you how to join their book club, or whatever." For that reason, SETI searchers have started conducting surveys for those tiny flashes of light as well as for sustained radio traffic.
http://cosmiclog.msnbc.msn.com/archive/2009/05/04/1921655.aspx