Distant Wanderers

Ly Ly/SETI Institute An Artist's Conception of the Allen Telescope Array, due to go into full operation by 2005 in the California Sierra mountains northeast of San Francisco. With its eventual collection of more than 1,000 antenna, its SETI target list will ultimately number as many as a million stars.

In truth, no matter how dogged our efforts to find extraterrestrial intelligence, and how advanced the technologies, SETI astronomers may still miss the mark. "Back-of-the-envelope" calculations on the median age of possible extraterrestrial civilizations suggest their technologies would be several million years ahead of ours. Thus, trying to detect their communications or signals in the radio and optical spectrums may indeed be as futile as trying to log on to the Internet by banging on a "talking" drum. How can we second-guess an extraterrestrial civilization that could be millions of years ahead of us, if we cannot accurately envisage what Earth technology will bring in only several hundred years? We've moved from basic laptop computers to wireless Dick Tracy-style communicating watches in 10 years. What will be wrought in 10 million years? As Stuart Bowyer, a retired Berkeley radio astronomer and long-time SETI advocate, reminded me, we are simply stuck with the physics that we understand thus far. Bowyer believes that even if other civilizations are very advanced, communication in both the radio and optical spectrums will remain viable, and, therefore, should remain central to SETI's overall approach. He asserts that in the next 40 years, or by the time NASA and ESA have produced high-resolution images of an extra-solar "earth", SETI astronomers will have had a "fair chance" of finding extraterrestrial technology.

But even if a signal, or "leakage", is detected, it would be doubtful that we could decipher it, unless it was intended as an all-points-directed beacon designed to be decipherable for any civilization that lay in its beam. Certainly, signal detection would confirm that we were not alone in the Universe, but true interstellar communication, even over short distances, would necessitate a transgenerational attitude of collective long-term effort. Signals sent and returned over distances as short as 10 parsecs would require a round-trip communication transit of at least 65 years, or basically a human lifetime. Sustaining such interest in the public at large may prove to be optimistic at best. Imagine a student in a third-grade class some time in the future: the teacher announces that SETI astronomers have just detected a signal containing a message from an intelligent technology-bearing extraterrestrial civilization on an Earth-like planet circling a nearby star. The announcement would initially be greeted with emotions ranging from excitement, consternation, curiosity, and bewilderment. Universities would likely offer whole new curricula based on how Earth's religions and philosophies would be affected by the news. The Nobel Committee would award prizes, and the media would have a field day. But by the time the message had been deciphered, and the international community had agreed upon and sent humanity's response, the student would hear the news of ET's reply as he was "getting the gold watch" at his retirement party. So, dreams of interstellar E-mail are slightly optimistic.