SETI is an acronym for the Search for
Extraterrestrial
Intelligence. It is the science of using telescopes,
radio and optical, to search the skies for signals from alien civilizations.
The idea of SETI began in 1959 with the publication of a paper in the
British journal Nature by Giuseppe Cocconi and Philip Morrison.
The paper discussed the possibility of the existence of alien civilizations
and how we might be able to detect them. Their conclusion was that the
easiest method of detection would be radio waves.
Radio waves were chosen because they are capable of traveling the vast
distances between stars and can be generated with reasonable amounts of
power. We have been sending radio waves out into space for more than sixty
years. All of our radio, TV, satellite, and radar signals are currently
spreading out throughout the galaxy. Perhaps they've already been detected
by someone.
At the same time as Cocconi and Morrison's paper was published a young
astronomer named Frank Drake was putting
together plans for the first search. The search, named Project Ozma, was
conducted in 1960. Over a two week period the stars Tau Ceti and Epsilon
Eridani were scanned for alien signals. No signals were found but the search
had begun.
In the 30 years since the initial Ozma search many others have been
carried out with more sensitive equipment, over much longer time frames,
observing thousands of other stars. So far no alien signals have been detected
but we've really only begun to scratch the surface. There are an estimated
100 billion stars in the Milky Way galaxy alone. To complicate matters further
there are millions of frequencies that a signal could be received on. It
may be that we just haven't looked in the right place at the right time
yet.