[extropy-chat] ANNOUNCE: Extropy Institute's Future

[Eliezer S. Yudkowsky]

Keith Henson wrote:
> 
> Beyond a size that isn't a lot larger than a human head, you are going to 
> get a society of minds or one that thinks very slowly.  But I have never 
> seen an analysis with numbers in it.

Human axons transmit signals at half a millionth the speed of light. 
You ought to be able to build a brain two million times as wide and with 
four trillion times the cortical area, which thinks at the same clock 
rate as human neurons, even if you don't miniaturize anything and just 
speed up the axons.

Admittedly, relative fanout will be smaller unless you miniaturize the 
axons.  That is, each neuron will talk to a smaller fraction of the 
total other neurons, because volume available for axons goes up as the 
cube of diameter, but cortical area goes up as the square, and N^2 
connections would go up as the fourth power.  But each neuron could 
easily talk to a constant number of other neurons; or fanout could 
increase as the square root of the total number of neurons.  And that's 
if you don't miniaturize the axons.

I think we can get brains significantly huger than human with the same 
relative internal bandwidth.

-- 
Eliezer S. Yudkowsky                          http://singinst.org/
Research Fellow, Singularity Institute for Artificial Intelligence