SETI's Achievements

In an article in Astronomy (Eicher, 1993), Carl Sagan stated: "Whether the results [over the next 20 years] are negative or positive, they will profoundly influence our views of ourselves and our place in the cosmos."

He was of course playing both ends in this prediction. And he surely was correct about the positive part.

The problem with a statement like this - and many have made them - is with the negative part. As we have seen, there can never be a final "negative result" from SETI. SETI experiments that do not positively identify an ETI signal are always inconclusive. The most that can be concluded from a failure to detect is that no transmitter of a given EIRP8 at the sites we scanned (for a directed star search), or of certain EIRPs and ranges in the directions we scanned (for an all-sky search), and fitting the other parameters of the feature space we scanned, was present and turned on at the times when we did the scan.

Considering how restricted this finding is, no SETI researcher is ever going to announce a final negative result, especially since such announcement would result in the closing down of his or her chosen profession.

So, what have SETI programs achieved over the last forty or so years?

There have been limited negative findings of the sort described above. No confirmed, positive detections have ever been announced.9 There have been a few "teasers" - signals that apparently originated from off the planet, with characteristics ruling out possible sources on man-made space platforms, but which were not observed long enough for verification procedures to be attempted.

Such have been the tangible results of all the SETI programs carried out to date.

Intangible benefits might include a positive impact on science education, through possibly having attracted students into fields of science and engineering. This has always been considered an important goal of a national SETI program.

Open SETI Historical Reviews of SETI The Cost of SETI: Funding and Defunding

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