[ExI] The Great Silence again

[spike]

>... On Behalf Of Damien Broderick
Subject: Re: [ExI] The Great Silence again

On 4/26/2011 12:59 PM, Keith Henson wrote:

>> They don't even build shells around their stars and dim them to IR...

>Are you absolutely sure?

Keith inserted the appropriate uncertainty with this comment:

 >> ...At least not that we notice so far...

Excellent.  Then Damien continued:

>Galaxies are surrounded by annuli of invisible mass, and there are vast
voids between clumps of galaxies. Not making any superstitious, glib claims
here, but it might not be *impossible* that radiating hyperintelligent
cultures would leave such footprints. 

This is one of the few areas where we have the ability to use our advanced
mathematical tools.  Robert and I worked some on this about 10 yrs ago: is
it possible that dark matter is actually a bunch of stars that have been
MBrained?  After we finished some BOTECs, he concluded that it couldn't be,
and I concluded that it could, with caveats.

I went over with him the conservation of momentum in photons and how that
would direct the absorption of energy and re-radiating some of the energy at
a lower frequency.  You don't need to be a physicist to get this, alls ya
need to know is that momentum is conserved and energy is not.  You need to
know that the energy of a photon is h*nu and the momentum is h*nu/c.
Robert concluded that an MBrained star would appear as a very deep infrared
star.  

I disagreed then and disagree now, under certain circumstances.  These would
be that the MBrain doesn't actually absorb and use all the energy available
to it, but rather uses the momentum of the photons to drag the star to some
other place.  Reasoning: if the nodes of an MBrain were to orient themselves
to reflect most of the light from the star toward the east, then the star is
very slowly dragged to the west, by conservation of momentum.  It really is,
although I recognize it strains the imagination.

Robert rejected the notion, based on his firm belief (very possibly true)
that an MBrain would never waste available energy just to drag the star
elsewhere, even if there existed something really cool at the other end such
as another MBrain.  It would devour all available energy to do more  and
faster calculations.  I argued that may be so, however, we don't know what
an MBrain wants to do.  We only know what we want to do.

>I'd been hoping to write something about this with Robert Bradbury, but
then he upped and died on us... Damien Broderick

That soaring brain left us with enough information that we can carry on from
where he left off.

If so, some of you young physics hipsters step up to the plate right now,
for I am very busy now with some family crises.  First assignment: given a
sunlike star, with 1 sun mass and luminosity, assume an MBrain reflects 99%
of the momentum eastward.  What is the star system's westward acceleration?
I calculated this about a decade ago, and it is in my green notebooks
somewhere, but I haven't the time to find it.  As I vaguely recall, it was a
few meters per square year, but that seems high to me now.  Hipsters, have
it done by this time tomorrow, and I will do it independently as a check.

DAVAI! DAVAI! DAVAI!  (That's commie for DO IT!^3)

spike