[ExI] Computronium planet.

[John Grigg]

I sure miss Robert Bradbury taking part in discussions like this one...


John  : (


On Wed, Oct 17, 2012 at 8:02 AM, Keith Henson <hkeithhenson at gmail.com>wrote:

> On Wed, Oct 17, 2012 at 5:00 AM,  Anders Sandberg <anders at aleph.se> wrote:
>
> > On 12/10/2012 08:35, Keith Henson wrote:
> >> The radiators would depend on what they were doing. Used for fairly
> >> slow access, a planetary scale device might not need to much cooling.
> >
> > Yes, but even a tiny energy usage per cubic meter would get hot fast. A
> > sphere with radius R producing P Watts per cubic meter will need to get
> > rid of 4 pi R^3 P/3 Watts. It can radiate from the surface, 4 pi R^2
> > epsilon sigma T^4 Watts. That gives an equilibrium temperature of [R P/3
> > epsilon sigma]^(1/4). So if R=6e6 meters,  P=1e-6 W/m^3 the temperature
> > will be around 100 K. For a milliwatt it will be 570 K - good for
> > cooking. A Jupiter-sized version would be just as hot with a microwatt
> > performance.
>
> Agreed.  Thinking of information storage without a lot of access.
>
> >>   It would be an interesting place, dark, faint spill of light around
> >> the sun blocker, land areas covered with rectennas, fast uploaded
> >> civilization in the depths heating the the oceans to steaming,
> >> freezing cold rain falling everywhere, vast rivers running off bare
> >> rock continents. Inside the simulation conditions could be as nice as
> >> anyone wanted, but the underlying reality would be stark, worse than
> >> Mordor. Be hard to detect though, since the shading disk would
> >> probably be circular.
> >
> > Sysop Sauron was watching the cooling indicators of Mount Doom. "We are
> > seeing a spike in server latency, what the heck are those heavens doing?"
> > "They are apparently running a cross-civilization marathon game. Should
> > be over soon when the NPCs have evolved sentience."
>
> Small and fast means a lot of waste heat in a small space.  Liquid
> cooling seems like a good idea to take the waste heat from hot
> computation nodes to where it can radiate to space.  I wonder what
> weather patterns you would get with very little sunlight and most of
> the heat coming from the oceans?  At what light level do the plants
> die?  Are Robert Kennedy's "Dyson Dots" and my power sat proposal on
> the evolutionary pathway to a dim earth?
>
> But this brings up a point.  What is the optimal distance from a star
> to do the most computation?  The further out you go, the more
> collector area you need to power the civilization.  Closer than some
> point gives you more power from the sunshade than you can radiate.
>
> Is a planet useful?   I think it does for a communicating, fast
> civilization.  But is it more useful than a fog of computronium?  At
> only a modest million to one speedup, stuff on the far side of the
> Earth's orbit will be over 2000 subjective years away just from speed
> of light.
>
> Keith
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