[ExI] Unsolved problems

[Damien Sullivan]

On Tue, May 27, 2008 at 06:56:42PM -0700, Keith Henson wrote:

> There are a number of ways it can be expressed, the most general is
> that computation goes up at most as the cube of the linear dimensions
> while propagation delays (at best speed of light) goes up with the
> linear dimension.  Human smartness may be dependent on two dimensions,
> the area of the cortex.
> 
> So a large chunk of computronium, if it is to be of "one mind" has to
> think slower than a smaller piece.
> 
> This leads to a human being able to think rings around a "Jupiter
> brain" because of speed of light delays.

Yeah, I suggested similar things on the Orion's Arm list.  A related
concern is how much of the "computronium" has to actually be specialized
bandwidth carrying information around.  You can get a bunch of different
"groupmind" architectures, such as bandwidth being linear to "brains"
but the timescale of overall integrated thought slowing down, or the
time scale remaining fast (subject to lightspeed) but bandwidth
ballooning as N^2, N being the number of normal "brains" involved.

Then you have physical limits, such as minimum energy involved in
bit-erasing, and thermodynamic limits on radiating such waste heat.
Which scales as R^2, not R^3, interestingly...

-xx- Damien X-)