Planetary Society Announces Support for Optical SETI The Planetary Society announced this week that it will support three projects that plan to look for evidence of extraterrestrial intelligence at visible light, not radio, wavelengths. The projects, two at the University of California, Berkeley and the third at Harvard University and Smithsonian Observatory, are at the forefront of efforts in the search for extraterrestrial intelligence (SETI) to look for signals at visible wavelengths, instead of the more commonly searched radio wavelengths. "We have been listening for alien signals for decades; it's time we started to watch for signals as well," said Louis Friedman, executive director of the Planetary Society. One of the optical SETI projects at Berkeley will look for pulses of light as short as one-billionth of a second coming from nearby Sun-like stars, as well as more distant star clusters, using a 76-cm (30-inch) automated telescope. The other Berkeley project will look for steady, narrowband signals in data collected in extrasolar planet searched by astronomer Geoff Marcy. The Harvard-Smithsonian experiment will also look for brief pulses of light using data collected by a 155-cm (61-inch) telescope located in Harvard, Massachusetts, west of Boston. Harvard's Paul Horowitz noted that, using only technology available today, a laser beam from a distant star would appear to the telescope as a thousand times brighter than the star. Optical SETI was first proposed in a 1961 paper in the journal Nature by Charles Townes, who later went on to win the Nobel Prize in physics, and R. N. Schwartz. However, the field has been largely ignored until recent years, with the only major work has been done by Stuart Kingsley, who operates a small observatory near Columbus, Ohio, dedicated to optical SETI. The SETI Institute, whose focus has been on radio SETI projects, recommended the optical SETI projects supported by the Planetary Society in a recent study, and is also helping to support the projects. Gamma-Ray Bursts May Explain SETI Silence Powerful blasts of radiation from an enigmatic astronomical phenomenon may explain why we have not yet seen evidence of extraterrestrial intelligence, one scientist has concluded. In an article to be published in the January 23 issue of the magazine New Scientist, Fermilab astrophysicist James Annis explains that gamma-ray bursts (GRBs) may have inhibited the development of intelligent life in the early universe. "If one [GRB] went off in the Galactic center," Annis said, "we here two-thirds of the way out on the Galactic disk would be exposed over a few seconds to a wave of powerful gamma rays." Such radiation would be lethal to life on land, he believes. GRBs occur in galaxies only once every few hundred million years today, but some theories suggest GRBs were more common in the early universe. Since a single GRB is powerful enough to sterilize nearly an entire galaxy, it may be only now that conditions have permitted the development of intelligent life here and elsewhere in the universe. "The GRB model essentially resets the available time for the rise of intelligent life to zero each time a burst occurs," Annis said. Such an explanation may be a solution to a half-century-old question on why we have not seen evidence of extraterrestrial life. The problem, proposed by Nobel laureate physicist Enrico Fermi and dubbed the "Fermi Paradox", notes that a civilization traveling at only one-thousandth the speed of light could traverse the galaxy in 100 million years, far less than the age of the galaxy or the universe. "Where are they?" Fermi was said to have asked rhetorically. GRBs, which may be caused by the collision of neutron stars or black holes, can release as much energy in a few seconds as a supernova. That short timescale could work against the theory, British physicist Paul Davies points out. "If the drama is all over in a few seconds, you only zap half the planet," he said. "The planet's mass shields the other side." Secondary effects from the blast, such as the destruction of the ozone layer, may be enough to wipe out life on the rest of the planet, Annis noted.