SETI again

On 7/28/06, Douglas May wrote:
(...)
> Perhaps SETI need not bother pointing their dishes at stars. Maybe
> there's no one there. Perhaps all the colonists are in the blackness
> and they shun stars and solar systems. Since 99.99999% of the galaxy
> is interstellar (using the heliopause at 100 AU as the boundary of
> the solar system proper), It seems logical that, if we can get there
> at all, and if we can meet our energy and supply requirements, that
> interstellar space is where most people will end up living. Once
> settlements set out on the several generation journey to a star,
> eventually they will get used to it and good at living. Perhaps they
> will wonder why anyone would want to be bound to a star.
(...)

I (and many others) have also wondered about that possibility. But the
problem with that hypothesis is that planetary systems offer quite
definitive advantages in terms of density of matter. Instead of
traveling hundreds of millions of kilometers to the next comet, inside
a planetary system you will have regions were a given asteroid is just
a few thousand kilometers away. And there will be even densest regions
in planetary rings and the like. So I find it hardly believable that
no colony among the trillions surrounding a planetary system would not
be tempted to tap all those tightly packed resources.

Years ago, this same hypothesis popped in this list (I think), and the
conclusion was that in such a scenario you would have a Galactic Ocean
(using your catchy poetic name) civilization very disperse and inside
this Galactic Ocean you would have many "Solar Island" civilizations
proliferating tightly packed around stars.