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

From: Robin Hanson (
Date: Mon Jul 16 2001 - 11:19:25 MDT

Robert Bradbury wrote:
> > 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, ...
>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. ...
>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. ... spectral
>properties and temperature of these would be similar to those
>previously stated, ... a lot of fiber connecting the internal
>nodes, ... needs a *lot* of silicon ... 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 ...

The peak temperature prediction is pretty weak, but the no
emission/absorption lines prediction seems stronger, though
it will probably be quite a while before that prediction gets
tested. How about a prediction about the motions of these objects?
Would you not expect to find them not attached to stars? How
close to a star would you expect to find them? If not attached,
how fast would they be drifting between stars?

Robin Hanson
Asst. Prof. Economics, George Mason University
MSN 1D3, Carow Hall, Fairfax VA 22030-4444
703-993-2326 FAX: 703-993-2323

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