Summary

Even though this paper does not deal directly with the question of interstellar propulsion, I felt it was appropriate to include here, since it does address the closely related problem of interstellar communication. After a short review of the efforts of SETI to the present day, the author offers several possible explanations for the lack of evidence of signals from extraterrestrial intelligence (ETI). One of them is that radio transmissions are inappropriate for the use of communicating between planetary bodies, due to their 'built in' sensitivity to interference from naturally occuring astrophysical phenomena, and their limited propagation speed (speed of light). He speculates that advanced civilizations would use a quantum based technology instead to achieve non-local (instantaneous) and disturbance free communication between very distant locations. After briefly reviewing the present state of our knowledge on quantum based, non-local effects (such as the Einstein-Podolsky-Rosen or EPR effect), he concludes with a call for further research in this area, pointing out the numerous benefits which even a small improvement of our understanding would yield.

Abstract

Radio searches for the evidence of extraterrestrial intelligence have been going on for 35 years, without success. Suggestions are advanced as to what we might conclude from this. It is argued that radio suffers from a number of weaknesses that might make it undesirable for a very advanced civilization to use for interstellar communication and that real-time communication with distant objects in space might be possible through the use of the special properties of the quantum world. If technologies can be devised that would trap and observe photons from distant reference points in space, they might yield evidence of extraterrestrial intelligence.

Paper