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Article 6344 of comp.ai.philosophy:
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>From: clarke@acme.ucf.edu (Thomas Clarke)
Newsgroups: comp.ai.philosophy
Subject: Re: Vitalism and Intellectuaism
Message-ID: <1992Jun22.141530.24412@cs.ucf.edu>
Date: 22 Jun 92 14:15:30 GMT
References: <1992Jun21.211451.3810@news.media.mit.edu>
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In article <1992Jun21.211451.3810@news.media.mit.edu> nlc@media.mit.edu (Nick  
Cassimatis) writes:

> Another caveat on the whole modelling quantum effects contreversy:
> since one mu st take into account quantum effects to design a
> transister today, one would thi nk that one would need to understand
> these to model the comptuer.  BUT WE DON't. The computer can
> completely be modelled as a turing machine.  Of course, thiswould
> explain what happens when you hit it with gamma rays, but that's not
> the s ort of understanding we want.  Why should it be any different
> with the brain --even if we must take into account quantum effects to
> understand the design of th e neuron?
> 
> -Nick
To my way of thinking, computers are not modelled as Turing machines,
computers are designed and built to BE Turing machines.  If any
non-deterministic effects sneak in, through race conditions leading
to metastable states in flip-flops, or whatever, this is considered
a design defect and is rapidly fixed.

Neurons are not nearly so well understood as transistors.  While 
transistors in computers are deliberately operated in regimes where
quantum effects are unimportant on the scale of the computer as a 
whole, the modes in which real neurons  operate in real brains are not 
so well understood.  It is of course entirely possible that evolution 
produced brains which operate entirely in deterministic modes,
readily modelled by Turing machines, but I have my doubts.

In fact see the July '92 Scientific American for an article about G 
proteins which communicate between and change the states of enzymes
and receptors bound to cellular membranes.  It seems entirely likely 
that a universal Turing membrane could be constructed from these 
components.  The components being molecular in size, quantum
effects would be hard to avoid.  

Kind of boggles the mind, the brain potentially being an array of
10^10 (quantum) Turing machines :-)
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu


