The Search for Extraterrestrial Intelligence is a quest to answer one of life's most intriguing questions: Are we alone in the universe?
Yes or no, either answer will have tremendous implications for mankind. Should the answer turn out to be YES, we are alone, then our race would be placed in a position of being the only creatures in existence capable of exploring such questions. We would be the supreme and only intelligence in the cosmos. A staggering thought.
If the answer turns out to be NO, we are not alone, then who else is out there? What are they like? What knowledge do they have? How do they act towards other races? What are their philosophies, sciences, and arts? The questions are endless, as are the possibilities.
We have the technology to communicate over vast distances - millions of lights years. We are capable of sending and receiving radio signals across the vast expanses of space. Actually we have been sending them for over half a century. All radio, television, and radar signals from Earth leak out into space and spread across the galaxy.
Perhaps some other advanced civilization has detected our signals and is now sending their own in an attempt at communication. The only way we'll know is to look and to listen.
That is exactly the premise behind SETI (The Search for Extraterrestrial Intelligence). The idea is to listen, using radio telescopes, for radio emissions from other worlds.
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 57 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.
But eventually, we will.