SETI-Where Are They?
Original Post: 4 June 2012
According to a Wikipedia article, Enrico Fermi, the famous physicist, had a conversation with some colleagues as a result of a rash of UFO reports in the 1950s. The conversation involved the possibility that we might someday be contacted by intelligent aliens. After doing a quick calculation which showed that Earth should have already been contacted, Fermi is said to have asked, “Where are they?” (This just after a discussion of UFOs!!!)
Considering the number of UFO reports that have not been classified as due to swamp gas, the planet Venus, hoaxes, etc., and the reports of strange beings in the various mythologies of terrestrial cultures, perhaps Fermi’s question should have been “Why didn’t they stick around?” Perhaps they did. But we have no hard evidence that we have been visited by aliens.
Still, the search for extraterrestrial intelligence (SETI) goes on. Much of the search seems to be for the purpose of detecting signals from intelligent alien races. This has always seemed a little foolish to me. We can only detect signals sent via electromagnetic radiation (light, radio, etc.) and these travel only at the speed of light (186,000 miles/sec),. Although this is pretty fast, the distances between planets in our solar system makes real-time communication from Earth for control of space probes out at Mars, Jupiter, or Saturn impractical. I can only wonder if the adjective “intelligent” would be appropriate for races (our own included) who think that communication with their neighbors over distances requiring years – perhaps hundreds or thousands of years – for a reply would be practical.
Well, if two-way communication is out of the question, how about just sending out a “Here we are!” message? Considering what has happened every time European “aliens” contacted aboriginal cultures around the world, perhaps this is also not such an intelligent idea. Aside from that, however, consider the prodigious amounts of energy required for such an enterprise. In the January 2012 issue of Sky & Telescope magazine, Joseph Lazio describes a variety of ways to send signals between stars. He also discusses the vast amounts of energy required for any of these methods. Why would any “intelligent” race waste such immense amounts of energy on such a silly mission? They probably wouldn’t.
Another ways to detect alien civilizations would be to listen for their radio and TV broadcasts. A sidebar to the Sky & Telescope article asked the question, “Could aliens listen to our radio or watch our TV?”. But it left out the answer to one important question: ”If the alien civilization was technologically similar to ours, how close would they have to be to detect our signals (or we, theirs)? I queried Sky & Telescope and my question was answered in their April 2012 issue. According to Dr. Lazio, the answer is “we could only detect ourselves slightly outside the solar system and certainly not farther than about 1000 a.u. [astronomical units].” For reference, Dr. Lazio pointed out that the Alpha Centauri star system, our closest stellar neighbor, is about 300,000 a.u. away.
Is it any wonder that the various searches for extraterrestrial intelligence have been fruitless?
Keep reading/keep writing – Jack