[ExI] SETI for Post Singularity Civ

[John Clark]

On Sun, Jan 18, 2015 at 1:32 AM, Keith Henson <hkeithhenson at gmail.com>
wrote:

> Re the whole topic related to M brains, Jupiter brains and related,nobody
> has ever answered my interrelated concerns of waste heat
> dissipation and speed of light delays. The laws of the universe, as I
> understand them, don’t allow for physically large objects to be fast
> thinkers.
>

A physical brain size no larger than a human seems like a pretty arbitrary
constraint to me. The fastest signals in the human brain move at a couple
of hundred meters a second, many are far slower, light moves at 300 million
meters per second. So if you insist that the 2 most distant parts of a
brain communicate as fast as they do in a human brain (and it's not
immediately obvious why you should insist on that)  then parts in the brain
of a AI could be at least one million times as distant. The volume
increases by the cube of the distance so such a brain would physically be a
million trillion times larger than a human brain. Even if 99.9% of that
volume were used just to deliver power and get rid of waste heat you'd
still have a thousand trillion times as much volume for logic and memory
components as humans have room for inside their heads. And the components
inside the AI would be considerably smaller than the components inside the
human.

  John K Clark
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