X-Message-Number: 14998
Date: Thu, 23 Nov 2000 13:58:56 +0100
From: Henri Kluytmans <>
Subject: Re: Clancy, brief comment

Pat Clancy wrote :

>But physical/quantum reality happens at infinite 
>precision, and the infinite precision "calculations" of reality happen
instantly - 

<snip>

>you cannot just calculate the positions and momenta of particles as they 

<snip>

>would not run in real time, i.e. that you could in theory simulate
sequentially 
>those things that were instantaneous in reality, 

<snip>

Of course, a discrete system cannot imitate an analog system (or 
a quantum mechanical system) with exact precision. However the 
question is : "Is exact accuracy required?" 

First of all, it doesn't seem likely that details at the 
quantum mechanical are essential for the functioning of 
the mind. (And that's what is the issue here.)
And it seems that most neuro-scientists tend to agree. 

If you think so, can you give me the scientific motivation 
as to why ?

(By the way, even an analog system cannot imitate an other 
analog system exactly in practice! Because therefore you 
would need to measure it with exact precision, which is 
fundamentally impossible according to physics.)

====

However exact precision is not required...

Any analog system is in practice being perturbed all the time. 
Indeed a single fluctuation in some quantum state(s) can determine 
the direction/result of our thought processes. But you don't even 
need quantum mechanics for that, a single particle or photon of 
background radiation could also do that. Or the fluctuation of 
thermal energy of a single particle in your mind. However our 
thought processes do not seem to be very chaotic... 

The question is : "What is essential for the functioning of the mind?"

====

Lets make this clear by an example :

A computer is also a system made of particles governed by quantum 
mechanics. Continuously there are changes and fluctuations in the 
quantum states of those particles. Are the exact states important 
for the functioning of the of the computer? ..NO  What is important 
for the functioning however, is the statistical behavior of larger 
numbers of particles due to their quantum mechanical states. 
Otherwise, for example, a transistor circuit wouldn't work. 
Analogously, the exact thermal states of the particles are not 
relevant. However the average thermal states of larger systems 
of particles is. The high level logic functioning of a computer 
does not depend on the exact states of the single particles.
But still a single particle or thermal fluctuation could determine 
the outcome of a calculation in that computer. (And that last one, 
is more likely to happen when your computer gets hotter.)

I assume you agree with all this?  (... for a computer)

====

So, because the functioning of our mind does not seem to display 
a chaotic behavior (for most people :> ) it seems that it's 
functioning is based on mechanisms that operate at a higher 
level, and that the fluctuations in the lower level mechanisms 
are statistically evened out.

Also randomly destroying a certain amount of single neurons does 
not seem to disturb the functioning of our mind. The same 
appears to be true for artificial neural networks.

This all seems to imply that we do not need to make 
an imitation with infinite precision, to imitate 
the functioning of the mind.

** With "functioning of the mind" I mean : "High level 
functions, like intelligent behavior, feelings, 
selfconsciousness."

Cheers,
>Hkl

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