I just came across two different perspectives about SETI (Search for Extraterrestrial Intelligence.)
Infrared light search:
The first was in an article in the June 2013 magazine "Astronomy." The article was titled "How to find ET with infrared light" by Jeff R Kuhn; Svetlana V Berdyugina; David Halliday and Caisey Harlington. Extracts from the article follow:
"Current and emerging earthbound technology makes it possible to obtain a census of ETCs within about 60 light years of us - just by evaluating the heat signatures of nearby stars." (p.30.) (ETC is short for extraterrestrial civilisations.)
"Thus a way to find such an advanced ETC...is to look for stars that are invisible or faint at optical wavelengths but bright in infrared emission." (p.30.)
"From Earth, we can see the radiated ETC heat as a time variation from the rotational and orbital motions of the planet around its host star as alien cities rotate onto the side of the planet facing Earth." (p.33.)
"The three largest infrared-sensitive scopes now in their planning stages (the Giant Magellan Telescope; the Thirty Metre Telescope and the European Extremely Large Telescope) might be capable of detecting 10HZ planets and, if scientists are lucky, perhaps one highly advanced ETC..." (p.35.) HZ is habitable zone.
"A telescope with a primary mirror about 250 feet (77 metres) in diameter, however, could find hundreds of Earth-sized or larger HZ planets, and perhaps dozens of ETCs, using a sensitive coronagraph - and the technology to build such an instrument exists." (p.35.)
Fermi's paradox: (click here)
The same day as I read the above article, I was also reading a book "Turing's Cathedral: The Origin of the Digital Universe," by George Dyson. Pantheon Books. New York. 2012. ISBN 978-0-375-42277-5.
In the year 2000, Dyson, interviewed 91 year old Edward Teller (click here to read about Teller.) Teller had been one of those present at Los Alamos, "...in 1950, when the subject of extraterrestrial beings came up over lunch..." (p291) with Enrico Fermi. Fermi's paradox was therefore 50 years old, and Dyson asked Teller "...how Fermi's question is holding up?" (p.291.)
""Let me ask you," Teller interjected, in his thick Hungarian accent. "Are you uninterested in extraterrestrial intelligence? Obviously, not. If you are interested, what would you look for?"
"There's all sorts of things you can look for." I answered. "But I think the thing not to look for is some intelligible signal...Any civilisation that is doing useful communication, any efficient transmissions of information will be encoded, so it won't be intelligible to us - it will look like noise."
"Where would you look for that?" asked Teller.
"I don't know..."
"Globular clusters!" answered Teller. "We cannot get in touch with anybody else, because they choose to be so far away from us. In globular clusters, it is much easier for people at different places to get together. And if there is interstellar communication at all, it must be in the globular clusters."
"That seems reasonable," I agreed "My own personal theory is that extraterrestrial life could be here already...and how would we necessarily know? If there is life in the universe, the form of life that will prove to be most successful at propagating itself will be digital life, it will adopt a form that is independent of the local chemistry..." (p.290.)
An interesting set of views.