[ExI] Fermi Paradox and Transcension

[BillK]

On Tue, Sep 11, 2012 at 6:11 PM, spike wrote:
<snip>
> Parting shot: if an MBrain is mostly transparent and relies on a mostly
> unobstructed view of cold space for heat rejection, such that we could see
> through an MBrain without much loss of light, and if it is fundamentally
> necessary that all MBrains must be constructed this way, this would explain
> why we haven't seen the signature of one anywhere.  We would be looking for
> a large cool object, when in fact an MBrain would be a dense hot object with
> a nearly invisible misty haze around it that would look a lot like a dust
> ring.  If we go with the Outback Postcards explanation for why we don't get
> signals from the MBrains (because the interesting stuff is all happening
> right there and they don't care about anything out here, and don't bother
> sending postcards to Aborigines during wicked cool technical talks) and
> MBrains must be mostly transparent, the universe could be filled with
> MBrains and we wouldn't know it.
>
>

Why not go to the source? The much-missed Robert Bradbury invented MBrains.
In 'Year Million', edited by Damien Broderick, Robert has a chapter
"Under Construction: Redesigning the Solar System."
I don't have a copy, but a review quotes:
MBrains, comprised of swarm-like, concentric, orbiting computronium
shells that use solar sail-type materials to funnel and reflect the
largest possible quantity of stellar energy.
-----------------

Looking back through Exi posts I find:
Robert J. Bradbury Thu, 2 Dec 1999
 The standard M-Brain architecture I designed, radiates heat only in
one direction (outward, away from the star). Each layer's waste heat
becomes the power source for each subsequent (further out) layer. To
satisfy the laws of thermodynamics and physics, you have to get cooler
and cooler but require more and more radiator material. At the final
layer you would radiate at the cosmic microwave background (or
somewhat above that if you live in a "hot" region of space due to lots
of stars or hot gas).
 Each shell layer orbits at the minimal distance from the star (to
reduce inter-node propagation delays) while not melting from too much
heat. [That makes the best use of the computronium in the solar system
since the different materials from which computers may be constructed
(TiC, Al2O3, Diamond, SiC, GaAs, Si, organic,
high-temp-superconductor, etc.) each has different "limits" on
operating temperature.] I suspect that some layers may be element
constrained (e.g. GaAs) and assume that diamondoid rod-logic computers
are not "best" for every operating temperature -- single-electron
Si-based computers, or high-temperature copper oxide superconducting
computers may be better in specific environments.

However it is important to keep in mind that the mass of the computers
in a node is probably very small compared to the mass of the radiators
and cooling fluid (this is the part that needs to be worked out in
detail).
-------------------

BillK