Progress in Searches for Extraterrestrial Intelligent Radio Signals

Abstract

Powerful searches for extraterrestrial intelligent radio signals have been carried out unsuccessfully for more than 35 years now. We should not be discouraged by the lack of success; our searches so far, as ingenious as they have been, have not begun to examine even a small fraction of the combinations of stars and radio frequencies which might produce detectable signals. Very powerful search equipment is required, as well as much observing time, in order to deal with the enormity of the possible locations and radio frequencies of intelligently constructed radio transmitters. Over those 35 years we have, nevertheless, gained much experience, while technology has improved in quality and cost at a striking pace. The application of the newer technologies, particularly digital computers, in the light of our experience, has produced search systems which are today as much 100 million million times more powerful than the systems of 35 years ago.