Re: SETI/ASTRO: MBrains/JBrains & Globular Clusters

From: Robert J. Bradbury (
Date: Mon Jul 16 2001 - 08:01:44 MDT

Anders wrote:

> Hmm, is the most efficient form of the mass of a globular cluster
> M-brains, or would it be quark matter brains (assuming them possible)?

When you show me the design details for the neutron-star computronium,
then I'll believe they are feasible. Until that time I'm sticking
with atomic engineering rather than sub-atomic engineering. Now
there are probably neutron stars circulating in the globular
clusters but they shouldn't make up 10% of the mass. One of the
interesting things is that there is a class of stars called "blue
stragglers" that appear to be the result of collisions between
white dwarfs and/or neutron stars. I would imagine the calculations
on how to use the fewest resources to cause these collisions (which
presumably result in the production of a lot of heavy elements) at
locations relatively "remote" from pre-existing computronium in the
G.C. (so the radiation exposure does not require extensive rebuilding
of the nanotech) is fairly non-trivial!

As a side note, I'll simply add that I think recent calculations
have shown that to get the platinium abundance observed in our
solar system, there had to have been such a collision nearby
around the time our sun was forming.

If it turns out that using natural "gravity" is more efficient than
using useful construction material for fusion breeder reactors dedicated
to the production of useful material (carbon, cobolt, etc.) then
advanced civilizations will leave the stars to do what the stars
do best. It may be that due to low metal abundances globular
clusters are terrible places to go early in galactic development,
but as astroengineering abilities increase (and you can skew
the rate of stellar collisions) they become very attractive
places to go in the long term.

> I think, if a cluster collapsed very suddenly
> in a fairly regular fashion into a quasar-like very small object). This
> seems to suggest a kind of Fermi argument against my Ouranos quark brain...

It might take you billions of years of orbital rearrangement to
get this to happen precisely the way you wanted. There are millions
of stars in many GC -- figuring out how to collapse them efficiently
(and setting it up) has to be the ultimate N-body problem. In the
M-Brain/J-Brain era, you can see the elders watching and saying
"Did you see what those children over in NGC 1349 did? They
collapsed the cluster 17.3 billion years too early and lost
3% of the available matter! I can't believe how careless
young people are now-a-days."

Technotrancendence wrote:
> Although it kind of makes for an unprovable assertion, isn't there a
> possibility of stealth here? Would Jupiter brains or your Ouranos quark
> brains want to call attention to themselves?

I don't think you care. Using IR telescopes & microlensing nothing of
any consequence is going to be able to approach you un-noticed. It
doesn't seem to be worth the trouble (at this stage of the development
of the universe) to run around trying to steal matter & energy (when
there is so much of it available that is "undefended"). So I don't see
any advantages to "stealth". If you are paranoid about the attack
of nearby neighbors, you just launch yourself into inter-galactic space.
I can't see any reason that anyone would want to bother with you there
until the universe is much much older (and resources much much scarcer).

> From my reading, the globular clusters don't currently have detectable
> planetary disks.

I'd agree. Low metal content early on should have worked against the
formation of planets and the radiation pressure from O & B class stars
(in both their formation stage and SN stage) would have blown any
gas/dust out into interstellar space, preventing formation of planets
at later stages of evolution in the cluster.

Anders wrote:

> Globular clusters are mainly older population I stars if I recall right, so
> if they have planets they will be low on the heavier elements we would like
> to use for megastructures, such as carbon.

Actually, it is the population II stars that are older, making up
the core and halo of galaxies as well as the globular clusters.

Also, you fall into the trap that the astronomers do of assuming
no astroengineering is occurring. If astroengineering *is* occurring,
the stars may be low in carbon because it is being recycled into
megascale structures. They may not be population I stars at all
but population IV stars (recycled stars consisting primarily of
the H & He left over after star-lifting has allowed the removal
of useful "metal" elements). There isn't any well developed
theory about how one optimally drives up the metallicity and
matching energy availability of a system. You can't just go
slamming large stars together because you lose all the material
down the resulting black hole gravity wells. Its a very tricky
process to direct the mergers of stars with just the right mass
to optimize the production of really heavy elements.


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