Le SETI et les investigations d'ovnis comparés

My perception is that the SETI (Search for Extraterrestrial Intelligence) and UFO studies of a decade ago shared positions beyond the pale of "respectable" science. They no doubt still do in the view of many scientists. However there have been several fundamental advances during the past few years that indirectly provide some increase in plausibility for both areas, and the SETI community seems to be responding with renewed vigor. It may be useful for our panel to consider some UFO-SETI comparisons, and the different cultures of their respective participants. These are my personal and incomplete thoughts on this subject.

There have been recent advances concerning the question of the possible existence and state of extraterrestrial life (ETL). Knowledge that there is such life would increase the presumptive probability of extraterrestrial intelligent life (ETIL). SETI investigators search for the latter mainly by examining the radio spectrum for telltale electromagnetic signals that may be purposely sent or inadvertently leaked from a technological society. UFO investigators may invoke visitation by ETIL as a fallback or default explanation of an apparition or event which they believe cannot be explained any other way. There are huge gaps in our knowledge that must be filled in before we can pretend to understand either of these subjects.

With regard to the first question, the existence and possible abode of ETL, three major recent developments are of particular note:

1. It is only in the last few years that we have finally obtained direct evidence of the existence a planetary-sized body orbiting a star other than our Sun. We now have evidence for several (of order of 10), and more are being discovered as the Doppler observational technique is being improved. There are billions of stars in our galaxy alone, and these results suggest that stars may quite generally be accompanied by planets. One may expect that conditions on these planets would vary over a wide range, at least as wide as the range covered by the planets of our solar system. (See, for instance, Cosmovici et al., 1997.)
2. Life that is fundamentally different from nearly all near-surface life on Earth has been found deep in terrestrial rock and in the deep ocean, where it exists under conditions long assumed to be so hostile as to be sterile. It would appear that near-surface and subterranean life forms are essentially independent and that either could exist without the other. It is also possible that life started several different times on Earth after epochs of total extinction caused by asteroidal and cometary impacts. These new findings suggest that life might have started independently at two levels on Earth, or that life can adapt to extraordinarily different environments. The development of life, under conditions that are thought to be favorable and under conditions that we previously thought to be unfavorable, may be the rule rather than the exception for the innumerable planets that probably exist in our galaxy. (See, for instance, Cosmovici et al., 1997.)
3. A meteorite found in Antarctica and known to have come from Mars (from isotopic "fingerprinting" of its elements) has several detailed internal characteristics (structural, chemical, and elemental) that may, it is claimed, be attributed to effects of ancient microscopic life indigenous to Mars. (McKay et al.,1996). This interpretation is controversial and research on this and other meteorites is continuing.

These subjects are currently being investigated widely and were featured among the many areas discussed at an international meeting in July 1996 held in Capri, Italy, on the subject of Astronomical and Biochemical Origins and the Search for Life in the Universe (Cosmovici et al.,1997). About 200 astronomers, biologists, chemists, physicists, and other scientists from 27 countries met for this Fifth International Conference on Bioastronomy and Colloquium No. 161 of the International Astronomical Union. This meeting was supported by international and national scientific organizations including the International Astronomical Union, the International Scientific Radio Union, the National Aeronautical and Space Administration, the European Space Agency, the Consiglio Nazionale delle Richerche, and other Italian organizations; clearly, this was a mainstream scientific meeting. The SETI community was very visibly represented in all aspects of the conference, but the problem posed by UFO reports was never mentioned.

However, the UFO and SETI communities share defining attributes including a surfeit of putative evidence that remains unidentified, and the lack of a single example that can be unequivocally verified, repeated, understood, or captured. That is, both are subject areas of investigation that totally lack identified objects. Then why is one moving into the mainstream of acceptable science while the other is not?

It may not be generally realized that the several different groups of SETI observers have received and tabulated an appreciable number of URS, or unidentified radio signals, in the course of listening to billions of radio channels for hundreds of thousands of hours, looking in tens of thousands of directions. They measure signals that are noise and signals that range up to many times stronger than can be explained in terms of natural noise. They identify nearly all of the strong signals as coming from radio and TV stations, from military radars and various kinds of communications systems, from satellites and deep space probes launched by various national and international organizations, and from many kinds of equipment that leak electromagnetic energy over broad spectral bands. After very thoughtful and vigorous winnowing, there has been a residual number of strong signals received by every group that are, and will no doubt remain, unidentified. But these are not described and released to the media as something unusual or mysterious. This is because they could not be verified by other observers or by repeat observations at the same frequency and in the same direction in the sky. Improved techniques and protocols are being developed to markedly reduce the frequency of URS (even to the point where there may be concern that a real ETI signal could be discarded). Nevertheless, it is to be expected that continuing URS will persist in the SETI endeavor, and will remain unidentified and undiscussed.

The SETI participants include a large fraction of scientifically trained radio astronomers, and they employ complex and expensive equipment that includes the largest antennas and most sensitive electronic and digital systems in the world. The UFO community is much broader and diverse, and cannot bring to bear the instrumental firepower that is routine in SETI research. In fact, no equipment is involved in most UFO case studies. The nature of UFO phenomena is such that it would be unreasonable to demand repeat observations of the same kind of incident and independent confirmation of events by different observers.

However, the status of UFO studies may be improved if we can find a way to move in a direction where independent confirmation and repeatability could be realized and become routine. Where some level of repeatability exists but explanations are incomplete (e.g., in the Hessdalen project), more investigative resources are clearly required. Open channels of communication between UFO investigators and a broader scientific group may lead to natural explanations of many observations and thereby winnow the numerous reports to a few notable examples to which intense cooperative efforts could be applied.