When Madame Le Chef was getting her undergraduate degree at San Francisco State, she was lucky enough to take classes from both Debra Fischer and Geoff Marcy. Since then these two astronomers, along with Paul Butler, have discovered 70 of the first 100 planets orbiting other stars. This past Saturday, Professors Fischer and Marcy gave a talk, which Mme Le Chef and I attended. It was very interesting.
Professor Fischer first explained the techniques (very ingenious) and the difficulties of detecting extrasolar planets and then Professor Marcy discussed current views on microbial life on “Earthlike” extrasolar planets and “technological” life (us) on same. There seems to be a strong consensus among exobiologists that microbial life is extremely likely to exist on “Earthlike” extrasolar planets and a growing feeling that “technological” life on those planets might not be very common at all.
The reason that basic life is thought likely is that there are many organisms on Earth that live in environments no less harsh than those on other planets. Prime examples are the algae and other organisms found in the boiling, sulfuric-acid laden water of the Yellow Stone geysers.
The reason for the growing doubt about numerous technological civilizations out there, is the total lack of evidence for their existence. Project SETI has been listening for alien transmissions for 40 years and has heard nothing. We have mapped the surfaces of the Moon and Mars and found zero alien probes or observation posts and, despite the claims of legions of whack-a-doodles, the same goes for Earth. There are numerous telescopes, with sensors across the entire spectrum of energy, looking out into space and there are no positive results---not even some gamma rays from a matter/antimatter drive.
Of course in order for us to detect another technological society, its time frame would have to overlap with ours and that could be very difficult. Professor Marcy did not get into our species’ history but I was struck by the thought that agriculture was only developed 10,000 years ago and cities were settled only 4000 (or perhaps 6000) years ago. In that short time (from a galactic point of view) we overpopulated the planet and developed multiple technologies that could destroy us. We could pop on and off the possible alien sensors when no one is looking, and so could they.
During the question period someone asked the “what if” question. What if the aliens weren’t like us and so we would not recognize their emanations. Professor Marcy revealed his Star Trek fanboy status by replying, “Yes, like the Horta.” He then pointed out that there are many creative people who can think of many possibilities but that as scientists they have to narrow things down so they can search for indications that are detectable with our current instruments. It’s up to the Horta to reveal themselves.