At the International Astronautical Congress in Bremen last October, and now in a bold new article in Acta Astronautica, SETI Institute astronomer Seth Shostak has gone on record, predicting SETI success within the next couple of decades. My respected colleague should know better than to make predictions, the outcome of which depends upon events completely beyond human control.
It is altogether reasonable to project the development of human technology, based upon past trends and planned investments. To say that we will have achieved a given number of simultaneous observational channels in a given time is merely an extrapolation of Moore's Law, which has thus far proven unassailable. Similarly, to state the number of candidate stars that we will have surveyed in a given timeframe is an altogether reasonable estimate based upon the experience the SETI Institute gained in ten years of Project Phoenix observations. But predicting the date (or decade, or even century) of contact is another matter altogether, because the 'other end' of the communications link is completely out of our hands.
It would be nice to think we know something about the existence, distribution, technology and motivation of our potential communications partners in space, but in fact, we don't. SETI seeks to detect not life (now believed to be abundant), but rather the communications technology such life might employ (and that's still a matter of pure speculation, the Drake Equation notwithstanding).
I, for one, do not subscribe to the Rare Earth Hypothesis widely articulated by Ward and Brownlee. That is, unlike those two scholars, I still picture a Universe teeming with life, much of it intelligent, some of it technological. Only I refuse to predict the direction which exo-technology might take. I subscribe instead to a Rare Photon Hypothesis: electromagnetic communication, appealing as it is to us, may well be the exception rather than the rule, as intelligent, technological and communicative civilizations develop signalling means the likes of which we cannot even begin to imagine.
I understand completely why Dr. Shostak has found it desirable to predict the date of contact. His SETI Institute is embarking upon an ambitious and costly venture, the construction of the World's Greatest SETI Telescope. The Allen Telescope Array is going to take a good deal of outside funding, and I certainly encourage the SETI Institute's fundraising efforts. Potential investors are going to want to know when they can expect a return on investment. The traditional SETI answer (maybe today, maybe tomorrow, hopefully in my lifetime, maybe never) just won't wash. So, Seth and his colleagues build optimistic mathematical models, in hopes of attracting funding. It may be fun, it's certainly intriguing, but is it scientific? I say it's no more nor less scientific than all the schemes out there to predict the direction of the stock market.
Dr. Shostak's prediction is reminiscent of similarly optimistic forecasts made by those brave pioneers who sold shares in high-tech startups, back before the internet bubble burst. If I make business decisions based upon his prediction, I will likely end up in the same position as those unwary investors who bought stock in those very startups: if not devastated, then surely disappointed.
To his credit, Shostak does specify what his prediction does not take into account. He writes, "We have not considered the luminosity function or duty cycle of extraterrestrial transmitters, but have instead assumed that the N transmitters estimated by the Drake Equation are all detectable... We have not speculated on the possibility that the frequency coverage of our telescopes is inadequate..." But these are the very considerations that must go into rational predictions of SETI return on investment.
Rather than responding to promises of contact, I am much more likely to buy shares in the concept of advancing our own technology, and through that, advancing human knowledge in ways that we cannot begin to predict. Construction of the Allen Telescope Array is an important step in that direction. In making such an investment, there is no way that I will be disappointed.
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this page last updated 7 August 2004
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