[extropy-chat] sjbrain calcs

[Robert J. Bradbury]

On Sun, 21 Dec 2003, Spike wrote:

> Tuesday 29 January 2002.
> Were you not in Silicon Valley Taxifornia on the date in
> question, Mr. Bradbury?  {8^D

I don't know -- that is an odd day for me to be in San Jose
(doesn't match up with Foresight conf. dates and the business
nano conferences have been in the LA region the last couple
of years -- but its possible)

> We theorized a .1 gram node, calculated some orbit mechanics
> assuming concentric rings of nodes one meter apart and the
> rings nested on one meter intervals (each ring a meter larger
> radius than the one immediately inside it) and each ring
> tilted a microradian from the next adjacent ring, so no
> intersecting orbits anywhere.

Better to say you calculated and I just watched... :-)

> You can practically do this stuff in your head, Robert.

You can -- I can't due in large part probably to lack of
practice -- but that is why I have a handy dandy spreadsheet
(ssmass.xls) which in the Planets worksheet puts Jupiter
at 43.27 light minutes out.  (Big :-))

I think you have this spreadsheet to play with on your hard
drive -- if not I'll be happy to send it to you.

> Do tell me you guys are old enough to have seen cotton
> candy some time in your lives.

Oh yes, and I won my high school girlfriend an extremely
large stuffed animal by climbing a angled rope ladder
(perhaps a 20-30 degree slope) that was suspended by a
swivel at each end.  (An interesting exercise in balance
and a lesson about what men will do for love).

> So the original question is a profound one indeed:
> can the SIRTF detect an MBrain?

A real star enveloping MBrain yes.  A Sandberg style
JBrain, probably yes as well depending on its distance
from us -- though if its external heat radiation temperature
is at 4K its going to be tough for 2 reasons (you probably
can't get 4K within the galaxy [Milan Cirkovic, Amara Graps
and I have been discussing this off-and-on] -- that would mean
that it would have to be outside of the galaxy which is quite
some distance.  If they are operating at a higher temp (say
20-40K within the galaxy) we might have a chance -- but the
detectors on the SIRTF aren't great at those temperature ranges.

The reason that MBrains and JBrains might be detectable
is because the radiation from the star doesn't outshine
the radiation from the MBrain and JBrain and the spectral
signatures are going to look *VERY* unusual.  A SJBrain,
probably has good odds as well -- subject to my constraints
of looking at the spectra at periodic intervals to detect
the fact that it is orbiting the star.  This would be
particularly true if it decides to optimize its energy
availablity by using both stellar energy as well as
energy produced by fusion reactors orbiting within
or around the computational cluster.

Anders' JBrain architecture is powered by external fusion
reactors similar to my comments about externally powered
MBrains.  How one gets from here (star powered civilizations)
to there (fusion reactor powered civilizations) is unclear.
It also isn't clear that one wants to do that -- gravity
is such a good containment mechanism for civilizations that
are short on metals that can be used for computronium,
data storage or other parts of ones energy capture,
heat disposal structure, communication and navigation
structures.

Robert