NOW THAT WE'RE around the 50th anniversary of two milestones in thehistory of our search for extraterrestrial intelligence (SETI) — the 1959 Nature paper by Giuseppe Cocconi and Philip Morrison that outlined the attractiveness of radio, and Frank Drake's first radio SETI experiment in 1960 (Project Ozma, see page 24) — it's a good time to reflect on where things stand with SETI. Numerous SETI efforts have been conducted, but they've searched such a minuscule sliver of parameter space (10-14 by one estimate) that the nondetec-tions don't tell us anything meaningful about the prevalence of extraterrestri-als. Truthfully, we simply don't know whether or not we're alone in our galaxy. But giving up is no fun, so I'll hazard a guess and hope some of you respond. Write to letters@ SkyandTelescope.com if you agree or disagree with me. If we use the height of the Eiffel Tower without the flagpole to represent the 3.8 billion years of life on Earth, the amount of time that human civilization has existed on the planet would be roughly the horizontal layer of paint at the top. I wouldn't be surprised if our galaxy has billions of planets with some type of primitive life, but the Eiffel Tower analogy suggests that only a precious few ever witness the emergence of a species capable of interstellar communication.
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