>> I don't think this is the _only_ sort of alien technology we should be
>> looking for, but it's certainly a good scenario. List members tend to
>I think it is exactly the right sort of alien technology to look for.
>Only this kind of civilisation creates huge, durable
>artifacts/high-visibility signatures, and quickly at that. Such
>civilisations are extremely expansive (because they get selected for
>aggressive expansiveness while propagating across the cosmic Petri
If you mean that the sorts of civilizations you describe would be the _easiest_ to spot, due to their expansive growth, etc., then I agree with you. My argument wasn't that we shouldn't be keeping our eyes out for such civilizations, merely that I think limiting ourselves to nanotech civilizations is just that--limiting.
>A civilisation below nanotechnology level is essentially
>incapable of interstellar travel.
Nanotech would be extremely useful for an intstellar mission. But _"essential"_? Agreeing whole-heartedly with your statement "Evolution is nonlinear, yet coevolutionary factors favour intelligence emergence," I think it's a contradiction to expect every single exploratory civilization to fit the paradigm you propose.
>I don't consider >10^4 year journeys
>in vast ecology bubbles to be interstellar travels.
If you can get to one star to another, it's an instellar voyage, regardless of what technology was used to get there.
>>that "exotic" ventures like interstellar colonization will necessarily rely
>>on all kinds of fancy nanotech, but don't forget that the idea of traveling
>It's not fancy, it's simply economical.
Certainly. But I'm not willing to make the _huge_ leap that every single interstellar civilization will rely on nanotech. "Variance" may well prove to be the key word, when the history of the galaxy is written.
>1) We cannot build stellar ramjets yet 2) anything we send out today
>will be very quickly overtaken by next-generation craft, because we're
>well underway to turn into a supertechnology civilisation.
Yeah, they would be overtaken. But what if the reason they left their home system was due to a cataclysm (or political/sociological stagnation) that stopped the technological advance that would have made nanotech a practical reality? What is an alien culture had some strange taboo against using nanotech for certain functions (i.e. spaceflight)? Et cetera. I think your argument suffers from a premature allegiance to the interstellar diaspora scenario.
I'm not arguing that your ideas are faulty, and I agree that we are becoming a suertechnology civilization (and _will_ become one--barring accidents). What I argue is the _inevitablity_ of this scenario, which is one of so many the list could fill volumes.