In the continuing search for an outer-space message, yet another earthbound seeker has been disappointed.
Harvard University radio astronomer Paul Horowitz has listened for signals beamed from the vicinity of 185 "likely" stars and has heard nothing.
It takes faith, patience and resistance to terrestrial discouragement to be an enthusiast for SETI (Search for Extraterrestrial Intelligence). None of the assorted astronomers, biologists and engineers involved in this international quest expects quick success. The universe is vast. Search capability is limited, and no one knows exactly where to point his radiotelescopes or at which frequencies to listen.
But, for SETI pioneers, hope is ever fresh. So, here and there around the world, they adopt what they hope is a sensible search strategy and scrounge what time they can to implement it with radiotelescopes - as did Horowitz at the U.S. National Astronomy and Ionosphere Center in Arecibo, Puerto Rico.
As he explains in Science, he worked out a listening technique that was at least a hundred times more sensitives that any previous SETI survey that has been reported. It was based on the assumption that the aliens would call us even if we hadn't bothered to call them.
Horowitz reckoned that they would be inteligent enough and "advanced" enough to have identified our solar system as an "interesting" target as which to beam messages. The signals would be intended to be picked up at the frequency of radio noise from cosmic hydrogen - presumably a universally known frequency.
Furthermore, these accommodating aliens would beam the message at a slightly different frequency so that it would arrive in tune with earthly receivers. This would take account of the fact that the motion of our solar system relative to the sender's planetary system would shift the signal frequency.
Horowitz then listened to 185 stars selected as likely, in his opinion, to have orbiting planets. The result has been another interesting SETI exercise, but no electronic "note-in-a-bottle."
Disappointing, yes. But it is not as disheartening as the stolid refusal of the Congress to fund the National Aeronautics and Space Administration's $2 million program to outfit existing radiotelescopes for a wider SETI operation. This would improve performance for regular radio astronomy work, too. It is not as annoying as the continual interference by earthly radio users. Nor is it as galling as was receipt of Sen. William Proxmire's Golden Fleece award for money-wasting activity.
But Horowitz's failure does point up a major SETI philosophical problem. He may have heard nothing simply because he didn't listen properly. How do you decide at which frequencies to listen or where to search? After all, assuming that highly advanced, intelligent aliens would find us interesting smacks of conceit.