Robert J. Bradbury made several thought provoking comments not restricted to but including:
> ...Fundamentally it comes down to the fact
> that we do not have the nano-capabilities to detect
> nanobots if they are here and we either do not have or only
> barely have the astronomical capabilities to detect SIs in space
> and to detect them you would have to look in "counterintuitive"
> locations (where we don't see stars)...
An even stronger argument could perhaps be fashioned thus: Most would agree that interstellar travel is just damn difficult any way you look at it. However we could, using only current technology, accelerate a payload to a reasonable fraction of c, then decelerate it once at its destination, if! that payload is on the order of a microgram, preferrably less.
The same thought process would surely occur to ET intelligences, therefore, they would likely undertake interstellar travel only *after* developing strong nanotech. Any holes in the reasoning so far? If this is the case, and an intelligence has managed to tinkerbellize [I believe that is the term {8^D] there would be no *advantage* to untinkerbellize or inverse-t-bell back up to meter scale, where they may have evolved intelligence in the first place. Is there? What advantage would that be?
If intelligence is generally on the micro or nanometer scale, this would explain why we dont see Dyson spheres. They would become unnecessary to micrometer scale intelligence, since they could gather all the energy they need without such mega-engineering projects. It could perhaps explain why the cosmos appears radio-quiet: the interstellar signals are at such high data rates [made possible by nanoscale computing] that we do not detect them. Furthermore, it would explain why we dont find alien lifeforms among us: we would not recognize them as alien. On the micrometer scale *everything* looks like the creature from Tralfamadore.
Im covering ground here that surely has been worn out years ago, now that I realize how obvious is this line of reasoning. spike