Scientists weigh prospects and results of swapping signals with other beings

Recent advances in science have vastly improved mankind's ability to communicate with extraterrestrial intelligence -- presuming it's there. Galactic colonization, probes to other stars, and laser communication could hold a promise of new possibilities for interstellar contact and travel, according to scientists attending the recent annual meeting of the American Association for the Advancement of Science.

``Between now and the end of the century is when the first message should come in,'' says Robert Jastrow, and ``it will be from a very advanced civilization.''

``For the first time in the history of this planet we have good reason to expect to hear from them -- if life is common in the universe,'' the Dartmouth astronomy professor continued.

Dr. Jastrow bases his forecast on the fact that our culture has been broadcasting television signals into space at the billion-watt level for more than 20 years. This is long enough for any inhabited planets in other solar systems to learn of our presence. Presumably it would take just as long for them to respond, which would be sometime in the next 20 years.

The National Aeronautics and Space Administration (NASA) is funding a project that seeks to develop the digital equipment necessary to pick up artificially generated signals at microwave frequencies. These are signals similar to what we use for communication purposes, such as long-distance phone calls.

Jill Tarter, a research astronomer working on the project at the University of California at Berkeley, says, ``Should we detect such signals, we will either have uncovered evidence for extraterrestrial technology or developed a whole new branch of astrophysics.''

Scientists have asked NASA for $77 million over the next 10 years to develop the necessary equipment and place it on large telescopes around the world by the end of the next decade. If successful in getting the money, the first systematic search for artificial signals will begin.

Dr. Tarter, however, is not convinced we will hear from another culture soon. ``I am extremely optimistic that eventually signals will be detected. I am not at all sure that it will be in my lifetime,'' she says.

Even if intelligent beings do exist on another planet, some scientists question whether they would let us know they exist. History has shown that radically different cultures often clash. If this holds true for different life forms, they might actually avoid outside contact. This, according to some experts, may explain the ``great silence.''

``We should not be so afraid that a future attempt to broadcast our presence will bring no results, as that it might bring far too many,'' Adelphi University Prof. Charles R. Pelligrino cautions.

Other explanations for the silence are that extraterrestrial life forms are not sophisticated enough to hear or respond to our signals, or that they simply do not exist.

Detecting evidence of other intelligence is just the first part of the equation. Some experts wonder if we will be able to ``decode'' messages sent from vastly advanced cultures.

Others wonder about the effect on people here of knowing that there is intelligent life elsewhere in the universe. ``The impact will not be so much scientific as political,'' Jastrow says, ``because these people, with the best of motives, may give us some very dangerous toys which will hold the key to political power.''

Tarter has a slightly different perspective on the impact. ``It will depend on the belief systems of the individual. We have looked at the potential for worldwide panic, and we don't find any kind of scenario that allows us to think that that would happen,'' she says.

One might wonder why, with all the other pursuits available to a well-trained scientist, some would choose a career more typical of movie producers and science-fiction writers.

``It will answer a question that the species as a whole has been asking for thousands of years,'' Tarter says. ``Are we alone?''