I have to disagree with all this messages must be beamed at us and supperior technology commentary. There are stars all over the sky. If an advanced star spanning civilization or even a simpler community of communicating civilizations spanning a large portion of the galaxy, I would think even modest beam dispersement levels would give us a chance of intercepting messages meant for others. Granted, a low number of communicating civilizations could easily leave us in the dark.

As far as technology goes the tribesman examples miss some key factors. Our technology has huge advantages over more primative methods, particularly speed and reliability. We do not expect to find any method faster than the electromagnetic spectrum based on current physics. The recent Dark Matter news suggests our physics is incomplete and this limit may be based on a flawed model, but you can't just handwave away the speed of light in a rational argument. We may find more efficient methods of using electromagnetic radiation such as fiber optic cables which do not radiate our communications into space, but I expect the electromagnetic spectrum will still be the basis for communication for centuries if not millenia to come. This comment also ignores the fact that the radio spectrum was chosen as the primary search frequency precisely because it is the best we know of.

It seems to me that to expect a medium of interstellar communication better than radiowaves or some other beamed portion of the electromagnetic spectrum is to expect our laws of physics to be over turned in a major way.

Regards,
Mark