[ExI] simulation

spike spike66 at att.net
Sun Dec 16 03:16:10 UTC 2007

> bounces at lists.extropy.org] On Behalf Of Bryan Bishop
> I know about mbrains and jbrains, but not about sbrains. Is this your
> computronium cloud from a few years ago on this same list?
> - Bryan

Ja.  I imagined a structure that was made from the materials of an earthlike
planet.  The botecs go thus: our atmosphere weighs about 100k newtons per
square meter, so that's about 1e4 kilograms, and the radius is about 6.4e6
meters, so squared is about 40e12 and 4 pi is about 12, so whats that, about
5e18 kg?

One percent of our atmosphere is argon which isn't good for anything, so I
imagine all the non-noble-gas atoms in the planet orbiting about the center
of gravity of the former rocky planet. The 5e16 kg of argon and all the
other noble gases stay at the center, loosely bound by gravitation, forming
a diaphanous sphere roughly 1e7 meters across, a couple atmospheres of
pressure at the center, decreasing exponentially to the point where the
density is below a few atoms per cubic meter, too few to interfere with the
innermost orbiting nodes.

In that scenario, the S-Brain is a couple light seconds radius, with the
nodes are a few hundred quadrillion atoms each.  Their mean distance from
each other is a few tens of centimeters, with the nodes on the dark side
receiving about a small fraction of a percent of the photons from the sun
(the photons pass thru the S-Brain to reach the dark side).  The entire
S-Brain rotates at one rev per couple years, if I recall the botecs I made
four years ago.

The idea is that unlike an M-Brain, which maximizes the amount of energy
available to each node, the S-Brain sacrifices total energy availability in
exchange for reducing latency between nodes.  As J. Andrew pointed out, and
I also eventually realized independently, latency will be always be a
limiting factor in parallel computing.

In a kind of analogous way, see how decreased latency in information flow
between people with the development of the internet has increased
dramatically the growth environment of memes.  Imagine if we didn't have
computers, but rather we were all typing out our ideas on paper and mass
mailing to each other.  It would take years to discuss what we now cover in
days.  In contrast, see how information now flows without friction, and how
ideas spring forth in such a tiny fraction of the time required in previous
eras, how debate flowers everywhere where once it was restricted to the
hallowed halls of the university, or the ivory towers of the think tank.    

Anders Sandberg had a talent for saying things in such a way as to inspire
ideas in other people's minds.  The idea for S-Brains sprang from some
J-Brain ideas Anders posted, which in turn were inspired by Robert
Bradbury's M-Brain notions.  I feel I contributed something to the idea, so
the dash brain can be attributed to Robert and the S can be for either
Sandberg or spike.



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