[ExI] SETI for Post Singularity Civ

Rafal Smigrodzki rafal.smigrodzki at gmail.com
Mon Jan 19 18:15:19 UTC 2015

On Sun, Jan 18, 2015 at 10:07 PM, Anders Sandberg <anders at aleph.se> wrote:

> Some more thinking:
> If we have a sphere with radius r with internal volume V(r) of
> computromium, the surface must have V(r)/X area devoted to cooling pipes to
> get rid of the heat. This can be formulated as the differential equation:
> V'(r)= 4pi r^2 - V(r)/X. The solution is V(r)=4 pi ( r^2/X^2 - 2 r/X - 2
> exp(-r/X) + 2) X^3. This grows as r^2 for larger r, so the average
> computronium density falls as 1/r as the system becomes larger.

### I think there might be a reason to build non-spherical devices as well
and the shape of the device will depend on the computations performed:
There will be reasons to build parallel and sequential hardware, and to
chain these two main flavors in various complex configurations. Our brain
is an example, although the limitations are not related to heat dissipation
but to minimizations of conduction delays - closely related simple tasks
are performed by small parallel computers in folded gyri which are then
chained to build larger sequences that perform larger tasks, with a lot of
special purpose connections running orthogonally and skipping parts of the
chain. It looks messy but it's because the task of staying alive in a
physical and social world takes a lot of highly structured, multilayer data
processing, with both parallel and sequential aspects.

I would then imagine there would be small devices performing the highest
possible density of operations per second per volume to solve tasks where
short conduction delays between logic elements are important. Then there
would be tasks demanding the highest overall throughput but little need to
reduce conduction delays and thus with little need to maximize density per
unit volume.

Maybe some tasks would then demand computers chained together like pearls
on a necklace. There would be disks, hollow spheres, and various seemingly
chaotic shapes, held together and apart by gravity, centrifugal forces and
maybe even radiation pressure. Probably the only constant feature would be
a high surface temperature, determined by the operating temperature of the
logic elements and the physics of the surrounding cooling elements. It's
likely that there would be many levels of organization where the
density/volume/speed tradeoffs would operate, from millimeter to thousand
kilometer, and who knows, maybe even light-year size.

Of course, reasonable people will wait a few trillion years before starting
the calculations to allow the ultimate heat sink to cool properly, and will
extinguish all stars in the meantime - and by seeing stars go dim we'll
know they are coming to our neighborhood.

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