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

From: Robert J. Bradbury (
Date: Mon Jul 16 2001 - 09:38:34 MDT

Robin asked:
> Care to make any predictions about observational features
> of these objects? That is, if they were MB or JB, what
> would that predict about them?

The Nature paper documents 7 events, 1 resolved and 6 unresolved.
The resolved event has a predicted mass of ~0.13 M_sun, which
would make it a red dwarf or white dwarf. It isn't clear whether
the HST should be able to see stars of those masses at 2.6 kpc
(M22's distance). The article does state that HST cannot detect
brown dwarfs (< 0.08 M_sun) in globular clusters.

If the resolved example is not a small star, then it could be a
Matrioshka Brain around a small star. The properties of that should
be a black-body radiation spectral emission curve (i.e. no "typical"
stellar absorption or emission lines in the spectra) with an peak
emission frequency indicating a temperature ranging from 2.7K up
to perhaps 2000K with a higher probability for temperatures in
the range of 63-373K. More accurate temperature predictions are
difficult because they depend to a large extent on how old the
Matrioshka Brain is and what material resources it has had
access to over its lifetime.

The 6 unresolved objects (because the HST didn't take images
frequently enough to provide the full light curves) have
a guesstimated mass of ~0.25 M_jupiter which would put them
clearly in the Jupiter Brain class. Alternatively they
could be Matrioshka Brains running off fusion reactors
(e.g. no internal star). I would presume that the spectral
properties and temperature of these would be similar to those
previously stated, but Anders might have other opinions.

I believe that Ander's Jupiter Brain design has a lot of fiber
connecting the internal nodes, if so, one needs a *lot* of
silicon for that. If the spectra of the stars in the GC
indicate they are low in C/Si/O relative to other less useful
elements (perhaps Na, K, Ca, He, Kr, etc.) then that could
be an indication that star lifting is occurring and the
useless materials are being recycled back through the stars
until they end up as something more useful.

Worth noting, is that *if* advanced civilizations choose
the "stealth" mode of existence, meandering gas giant
planets would make excellent homes. Lots of gas to
shield the nanotech from external radiation and anyone
below your technology level is highly likely to assume
it is a "natural" object. Its only when you notice one
of these sucking up hydrogen from a star or gas cloud that
you are going to get suspicious. You have to keep in mind
several of the gas giant planets in our solar system radiate
away more energy than they receive from the sun and we just
*assume* (with some calculations to support the idea presumably)
that this is heat remaining from the initial planet formation and
ongoing gravitational compression.


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