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

From: Robin Hanson (
Date: Tue Jul 17 2001 - 07:17:08 MDT

Robert Bradbury wrote:
> > How about a prediction about the motions of these objects?
>Scot Stride from JPL pointed out to me that the unresolved
>observations, interpreted as planetary mass objects, are
>making the transits at extremely high speeds. ...
> want to limit the length of time you are "near" the
> stars to limit heat and/or radiation exposure.
> ... communication throughput is ... limited by ... time it
> takes you to reach the next launch/receipt point
> in the cluster. If that argument has some merit, then the
> objects may select orbits that have relatively high velocities.

I was hoping to get theory predictions from you *before* you saw
the data, but I guess it's too late for that. Still, it might
be worth following this argument through to see what velocity
it suggests.

> > Would you not expect to find them not attached to stars?
>A classical Jupiter Brain, presumably has to get power
>someplace, so I'd expect to find it around a star with
>an array of solar collectors at its disposal. A fusion
>reactor powered Matrioshka Brain doesn't have that restriction.

So does this imply a correlation between object mass & attachment?

> > If not attached, how fast would they be drifting between stars?
>If the information transfer argument above doesn't hold,
>then you would probably adopt a speed that minimizes
>the matter & energy expense of orbital course corrections.

OK, might be worth estimating this velocity too.

>In short, I don't think one can make "good" predictions
>other than spectral characteristics at this point.

I realize that it would be more work to make these estimates,
but this does seem the key datum that you have to predict soon.
As you know I'd estimate a pretty low chance that these things
are MB/JB, but I am interested in thinking about how to check

How solid is the spectral prediction, btw? That is, how much
negentropy would they lose really if they allowed some spectra,
and how do we know that isn't worth trading off for something

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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