# [ExI] mbrains again: request

Eugen Leitl eugen at leitl.org
Wed Sep 28 15:03:48 UTC 2011

```On Wed, Sep 28, 2011 at 07:45:30AM -0700, spike wrote:

> Hmmm, the adjacent rings have very low relative velocity.  I need to refresh my
> memory from a long time ago, but a typical design had a ring of MNeurons spaced
> at one meter with the next ring a meter larger in radius tilted at a microradian.

Where did the one meter spacing come from? There's an obvious advantage of
using a closest packing of computational cells to minimize signalling distance
and maximize performance, which is then only limited to maximum dissipable volumetric
power density. As a hunch, that volume would be cubic meters, not cubic mm.
Depending on the power, that would be km^2 of PV/sail/radiator surface, with according
elbow room to spare for sail maneuvres, and such -- that would be some 1-10 km
spacing at least. That much space is not a problem relativistically, as high-order
processes would be slow anyway.

At that size the speed delta would be enough to wreck the sail. Loss of orbit
control would bring nodes from nonadjacent layers to collision.

> The relative velocity of an MNeuron in adjacent rings was on the order of a

It's a node, not a neuron.

> few cm per second.  Wait, I might be able to do that to a single digit in
> my head: a microradian at I AU is about 150 km and it has three months to

I see no reason to go to down to Mercury orbit for the inner layer, or shortly
above.

> get there is about 1.5e5 meters and has about 8e6 seconds to get there and
> since it is a sinusoid you multiply by pi so ja, I am getting about 6 cm/sec
> relative velocity without messing up an envelope.
>
> 6 cm/sec, ha!  Childs play.  I see no reason why we would ever risk a runaway collision catastrophe.
>
> >...Is it even possible to push the entire assembly by emitting radiation mostly in one direction, climbing up in a higher orbit half the time, and descending down the other half?
>
> Ja I don't see why not.

I'm not sure random orbit corrections balance themselves out so that
you can fire at will most of the time. The emergent behaviour strikes
me as potentially extremely hirsute.

> >...It's probably analytically too hard, so somebody could model it... Eugen* Leitl
>
> I am already working on it against time pressure.  The pitch is on 4 November, and I need to have the answers in time to get the paper to the printers.  My spreadsheets for equilibrium temperatures are not as solidly grounded as my orbit mechanics.  {8-[

It would be interesting to model as a swarm, with each agent given
behaviour constraints to conserve.

--
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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