[extropy-chat] sjbrain calcs

[Robert J. Bradbury]

On Sat, 20 Dec 2003, Spike wrote:

> Not necessarily.  The station-keeping ability of a solar
> sailing node is not dependent upon its area but rather upon
> its thickness.  For a given thickness of material, the
> mass and the area (thrust available from light pressure)
> scale directly together, or cancel.  If I can make nodes
> 1000 atoms thick, it doesn't matter if they are a square
> micron or a square millimeter in area, right?

Hmmm... this raises some interesting -- are you intending to
harvest the PV energy and use it to power your micronodes?
This raises the questions of whether you can vary the photon
absorption v. reflectivity ratio and whether you can have
directional heat emission out the backside?  If one imagines
an arrangement of TI micromirror like frontside and backside
architectures things get interesting.  On the frontside
you have one side of the micro-planar device(s) be reflective
(functioning as a solar sail) and the other side of the
micro-planar device(s) be absorptive (functioning as a
solar cell).  Obviously if one can vary the angle and
number and location of absorptive v. reflective devices one has
some interesting attitude control v. power consumption
capabilities and tradeoffs.

Then on the back side, the best heat radiator would be
a planar surface that radiates omnidirectionally -- but
with an micro-planar array of radiators one presumably
can tilt them to preferentially radiate in a specific
direction.  Probably isn't as efficient as the reflective
capabilities of the frontside array but you have to dump
the heat someplace anyway -- why not use it for navigational
purposes?

I would guess the optimization of power intake, attitude
control and heat radiation efficiency is going to be
reasonably complex and highly dependent on the computational
and communications architecture (nobody has discussed
what kind of effect inter-node photons for communications
purposes might have...).

However, Spike/Mike/Eugen -- I suspect that to cram this
much hardware into a node (micro-mirror type arrays,
nanocomputer, communicatiosns capabilities) even using
nanotech is going to result in something slightly larger
than "dust".  It may however be much smaller than the
architecture for MBrains.  That assumed 100,000 W
Drexlerian 1 cm^3 nanocomputers for the greatest computational
density per node.  And one needs rather large solar arrays
to collect 100,000 W.  An JBrain on the other hand tended
to be optimized for greatest internode communications
capacity.  An SJBrain seems to fall someplace in between.

In terms of distribution of ones mind/copies in an MBrain
architecture each node has the capacity of perhaps a
million human minds.  In a SJBrain I doubt the nodal
capacity is that high.  You may have to distribute your
mind over a number of nodes within the same orbital
ring.  Its going to make for interesting social structures.
You can of course always talk to your nearest neighbors
within your orbital ring and they can talk to their
neighbors and so forth.  Communications delays go
up depending on the number of hops.  But things
get more interesting if you want to talk to an
individual orbital rings inward or orbital rings
outward from your current position.  The highest
bandwidth/minimal delay time seems only likely to
take place when the individuals have orbited to
within their nearest distance to each other (kind of
like scientists on Earth sending probes to Mars every
few years taking advantage of when the trip will be
fastest).  Otherwise you have to transmit the data
to the nearest inward or outward node, it has
to go around that orbital ring, the reply comes
back around that orbital ring and then probably
gets communicated back to you by a different node
within that orbital ring.  But that is slower because
all of the nodes are handling a certain amount of
non-self traffic.

Obviously ones greatest bandwidth will be to nearby
individuals within ones on ring.  And so it is likely
that they will form the most powerful multi-minds.

Robert