[sci.philosophy.tech] the N-body problem

Nagle@cup.portal.com (John - Nagle) (12/26/89)

     1.  Remember that the physical world has noise.  The uncertanty
	 principle limits the precision of any analog simulation.

     2.  Recent work has resulted in an effective way to solve N-body
	 problems to an arbitrary level of precision and with high
	 speed.  See "The Rapid Evaluation of Potential Fields in
	 Particle Systems", by L.F. Greengard, MIT Press, 1988.
         ISBN 0-262-07110-X.

         Systems with over a million bodies are now being solved using
	 these techniques.

     3.  Biological neurons are rather noisy components.  If you would
	 like to see this for yourself, stop by the Exploratorium in San
	 Francisco, where a slug neuron has been wired up to a signal source
	 and a scope, and you can play with the inputs while watching the
	 output.  

	 The overall behavior of a neural system doesn't seem to be that
	 sensitive to the exact transfer function of each neuron.  If it
	 were, of course, brains would be much more fragile than they are.
	 This comment applies to both biological and synthetic neural systems.