The SETI lottery

A question that occasionally comes up in skeptical circles is the scientific status of SETI (search for extraterrestrial intelligence). Some claim that it is a pseudoscience while others defend it as sound science. Although I do not believe it is pseudoscience, I think that it sometimes can be very weak science.

SETI does not have the approach to evidence that pseudoscience has. It does not reject criticism like pseudoscience. It does change it's approach in response to evidence or criticism. It is not based on theories that contradict known theories. Falsifiability is a little trickier. It is not clear how much negative evidence is required to reject the search. At best we can put a limit on the number of stars that might contain intelligence. Even that is weak, because intelligence may be communicating with us in ways that we are not searching. But SETI does not have the built in barriers to falsifiability of many pseudosciences. More importantly, SETI has been objective in it's criteria for acceptance.

I think the most important question for it's legitimacy is how it would react to a positive signal. If we got a putative signal, I believe the scientific and SETI community would rigorously dissect the evidence. Althernative explanations would be sought out, and if better explanations were found, then the case would be rejected. I say that based on how the community has behaved so far. If however, the SETI community grabbed on to some possible signal and clung to it with layers of excuses even as evidence against it mounts, the same way that PSI researchers cling to weak evidence for ESP, then it would be a pseudoscience.

Although SETI is not a pseudoscience, that doesn't mean it is necessarily good science. SETI is unusual as a science because it has no actual data. There is no theory. It is just a search. The biggest problem is that the search is based on nothing but speculations, largely based on our knowledge of one society, 20th century scientific humans.

There is no reason to believe that any other intelligence would care to communicate with other intelligences, just because we would. There is no reason to think they would put rescources into sending out a strong signal. We haven't, why should they? In the 20th century, we used radio communication a lot, so the search has focused on radio signals. However, it is likely that we will replace radio signals with fiber optic or other means of communicating before too long. Our period of radio communication may only exist for a century or two.

SETI searches particular frequencies of the spectrum because those frequencies would make the most sense for an intelligence to communicate with. Again, this assumes they want to communicate and that they think in a manner similar to us and that they have the rescources available to devote to sending out a beacon.

Some speculations are pure science fiction. There was a recent study that looked for so called "Dyson spheres". These are theoretical massive solar energy collecting panels encircling a sun. There is no reason other than imagination to think any civilization would ever make these. Even if they are made, the study relied on assumptions about the infrared signal they would produce. There are reasons to believe Dyson spheres would never be made. The massive amount of material needed to make a significant number of these is way beyond our technology. There have been proposals to collect solar energy just from earth orbit, and we haven't managed to do it. It wouldn't be economically feasible for a long time. Maybe in a century we could have a few orbitin the earth. And yet people envision millions of square miles of these orbiting a sun.

Often, as in the case above, we assume that an advanced civilization would have massive capabilities. We envision a future like the Jetsons. Do we forget that we were supposed to be living in the sky by now, if you asked people 60 years ago? Humans left near earth orbit between the years 1969-1972. We have not returned, and won't for at least a few more decades. Much as I wish it were otherwise, I doubt humans will ever leave our own near vicinity. There is a strain of technological utopianism in much of science and SETI. It ignores economics and social forces. It ignores the limits of technology, or the unpleasant side effects.

The usual argument given for SETI, in the face of the long odds and large amounts of speculation, is that the pay off would be so enormous that we should go for it, even with long odds. Kind of a Pascal's wager of science. I agree that a postive outcome would be one of the most thrilling results we could have. If it can be done with minimal investment of resources, and there are people willing to devote their lives to it, I have no objection. However, I would object to any significant investment of resources, and I myself could not spend my life on SETI. It seems very much like buying lottery tickets and hoping for a pay off.