Wheis ET?

>
> > At a stellar level our ability to detect anything out side of our
> > solar system approaches zero, so a re-ordered solar system 100 LY
> from
> > here would be undetectable. Anyway how can we tell between
reordered
> > or not?
>
> I think replicators present the possibility of re-ordering a solar
> system on a scale visible from 100 LY.
>
> Dyson said we would be able to spot a re-ordered solar system via a
> shift in stellar spectrum to infra-red.

We have detected thousands of stars that have a visible shift in the
solar spectrum to infra-red. They are called Red Giants, and our
theory of stellar evolutions was created to accomodate them.

I agree if we could watch a stellar spectrum shifting then we could
spot a re-ordered solar system, but if we were to survey the skies at
any time, there is no way we will tell the difference.

>
> I would expect any civilization (whether composed of flesh-and-blood
> or silicon and steel) operating free of planets and using asteroids
> for resources to be far more visible than any planet-bound
> civilization.

I think you are showing your prejudice for large populations. If for
example my solitary AI had a programmatic disposition to being alone,
and dispersed itself accordingly there could be 1 to 1000 of them in
our solar system in the asteroid belt. They communicate with direct
laser beams. They have an aversion to being social so they don't
communicate often, and couldn't tell the difference bewteen life forms
and weather patterns. it is possible they wouldn't know we existed.
And because they don't communicate often they don't monitor the radio
band from earth and don't watch the simpsons 5 nights a week. This Ai
could be quite content in its own little world, solving some math
problem for the last 1000 years. If this creature has no impetus to
explore or prefers to deduce the workings of the universe from first
principals rather than by observation, how do we know its out there?
Even if we observed it we would pass it up as an asteroid because our
resolution couldn't see it as anything other than a point of light.

Bill