"is there some theoretical limit that I'm missing?" Well, considering that the closest star (Alpha Centauri) is 4.367 light-years away, that only means that if

"is there some theoretical limit that I'm missing?" Well, considering that the closest star (Alpha Centauri) is 4.367 light-years away, that only means that if something's wrong with the transmission itself, we can figure it out only after almost nine years. Other than that, I don't really imagine any feasible solution for communication on interstellar scale other than laser-based one, so my initial point was put forward exactly in that use-case. If there ever will (and I hope it will) be a galactic-scale communication system, humanity will have to: - Improve the current laser technology to the point of sending laser beams without much dispersion over light-years distances. - Improve the optical sensor technology in order to receive (and distinguish) from (multiple) artificial sources of light orbiting close to a noisy star. - Set up the laser system(s) taking in account: the time-frame of the moving celestial bodies - both stars and the orbiting emitter(s)/receiver(s), the gravitational time dilation factor, other currently known factors that I don't know of (I'm not a professional physicist), and whatever any other new additional subtle effect that may be still discovered in such setting! I think this fine calibration will be the cake's top-cherry, BTW. So yes, theoretically all is just an engineering problem. The development speed cycles of such systems though, are already dictated by the laws of physics - years (and in human time - generations). The mere reliable communication on such scale will be a great success, but I don't dare to hope of sending brains of knowledge['] in mere hours. ['] http://www.scientificamerican.com/article/what-is-the-memory-capacity/ http://www.scientificamerican.com/article/what-is-the-memory...