Re: MEDIA: NOVA on Gamma Ray Bursters

From: Robert J. Bradbury (
Date: Sat Jan 12 2002 - 05:36:50 MST

Some comments related to Spike's comments.

The critical point Spike makes is the fact that stellar
civilizations don't go anywhere "quickly". There is a
big difference between "colonizing" at a milli-c vs. 0.1 c
(a figure typically used for interstellar travel).
You can go quickly in a small ship -- but then you are
a "seed" (perhaps with no qualms about returning to
steal the resources of the parent). If you go as
the entire civilization (so you maintain internal trust
levels), you travel by the slow boat. This *significantly*
impacts any thoughts that the galaxy should appear "colonized".

Now, the inability to preserve trust relationships with "seeds"
*also* dictates ones behavior with regard to any civilization
*stupid* enough to allow seeds to be spread. Since you know
that sooner or later you will have to deal with a weed-filled
garden the best thing you can do is stop them before they
spread very far. Thus MBrains should have a scorched earth
policy with regard to seed spreading civilizations when they
are discovered.

You have to keep in mind the problem of the lack of "current"
information. If you assume that the time of development of
civilizations to time of the singularity is ~2000-5000 years,
then its clear that we don't have a clue what is currently going
on in most of the Galaxy. We are ~24,000 l.y from the center,
never mind the other side.

You can never know what the "reality" is outside of a very
local region of space. So chasing after a star 10 l.y. away
may make sense. Chasing after a star 100 l.y. away is iffy.
Chasing after a star 1000 l.y. away seems really silly --
you have no way of assuring it will still be there when you
finally arrive.

One point that wasn't clear to me from Spike's post was
what the point was of going to another system. You can't
harvest material from the stars quickly. So the only thing
you can do is rip off the planetary material. If the universe
is in that condition we would expect to find regions of space
where there are clusters of stars that "should" have planets
but don't (as the MBrains migrate outward in orbits plucking
the apples from an everwidening circle of trees). This is a
relatively solid prediction -- when we can do large exoplanet
surveys (e.g. the Kepler mission) if we find regions of stars
that are missing planets then MBrain activity is one reason
to consider (stellar near-misses being another possibility).

It looks to me like advanced civilizations should be able to
detect MBrains. You can see them either by their microlensing
signatures or slight variations in the background temperature.
*But* such signatures are always "past" signatures. How accurately
they reflect reality depends on their distance. If its under the
control of an "intelligence" any information about where it "was" gives
you little predictive power of where it "currently" is (within laws of
physics limitations regarding changes in velocity and direction of

The maximum amount of material - millions of stars worth is
going to be in large gas clouds (the question is is it cheaper
to collect it there than extracting it from a stellar gravity well).
If efficient ways to collect material in gas clouds can be devised,
then MBrains feed off those rather than stars.

It seems to me that MBrains don't have to "fight" -- not at this stage
of development in the Universe. There are lots of brown dwarfs to feed
on. But if MBrains can detect other MBrains and if one subscribes to
the "fighting" scenario, one would want to avoid any region of space
another MBrain could reach by the time you could get there. As the
MBrain population of a galaxy increases, it would seem that would
require expanding outward occupying an increasing volume of space
around the galaxy.

All this would seem to dictate an evolutionary strategy.
When resources are abundant, you can afford to be a
large slow MBrain and take your time getting to the
next gas station. But as resources diminish and become
increasingly less dense -- you have to be able to
get there faster. That would require that you have
an increasingly less mass (so you can accelerate,
decelerate and alter course more quickly). Unless there
is some breakthrough to subatomic engineering that suggests
to me that in the long run advanced civilizations will
be required to shed matter (and therefore memory and
intelligence). Alternatively one can consume the resources
more slowly, presumably spending much of your time in
suspend mode.

You can obviously move to locations where the matter
density is high such as galactic centers, but this
would seem to be a counterproductive strategy because
you are eventually going to get sucked into black holes
that are growing much faster than they are evaporating
(at least at this stage of the Universe). You can of
course get away from them -- but only by expending
a significant fraction of your resources.

Thus the really long term prospects for SIs do not appear
to be very good to me at this point (unless you want to
invoke magic physics).


This archive was generated by hypermail 2.1.5 : Fri Nov 01 2002 - 13:37:34 MST