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To succeed at last, we must embrace many failures. —Donald Goldsmith and Tobias Owen, 1980! Since 1960, scientists have conducted more than 100 searches for signals from extraterrestrial civilizations.’ As of this writing, there has been no confirmed detection of alien technology; although searchers have spotted many intriguing signals, none have been found a second time. It now seems clear that pioneering SETI experiments were based on overly optimistic estimates for the abundance of extraterrestrial civiliza- tions sending out radio signals. Shklovskii referred to the early period of SETI as the time of “adolescent optimism,” in which searchers placed exaggerated emphasis on the radio-technological prospects for extrater- restrial communication while ignoring both the humanities and biology. Drake admitted as early as 1976 that “if there were once cockeyed opti- mists, there aren’t any more.”* Some SETI pioneers had been realistic about the short-term prospects. Bernard Oliver said in 1981 that he did not expect to make contact with any of the things being done then; that was a dress rehearsal, learning how to parse signals. The sensitivities were not high enough to make a detection probable. Drake did not assume that the later Project Phoenix would be successful; the numbers were against it.° “Everything we have learned since 1960 tends to reduce the likelihood of success under the Drake Equation,” said James Trefil in 1988, before astronomers began discovering planets around other stars. Robert Rood thought it more likely that increased knowledge will decrease our estimate than increase it, although he acknowledged that the uncertainty is great.° 113 Should We Continue the Search? Looking and hoping are what science is all about. —John Casti, 1989? Premature Opinions