X-Message-Number: 15397
Date: Sat, 20 Jan 2001 11:23:34 -0700
From: Mike Perry <>
Subject: Ongoing Discussion, Computers and Brains

Thomas Donaldson, #15388, says:
...
>Yes, a "brain" in which all N neurons connect to one another will have
>N^2 total connections. However 
>... we should consider the set of possible connections
>(which necessarily involves connections which DO NOT exist as well as
>those which DO) ... ie. the fact that the total number of possible 
>connections is N^2 means nothing at all about what I've said, or the
>operation of brains. 
>

It sounds like you're saying that information is stored in the absence as
well as the presence of connections. (Yes?) No argument there. The amount of
information, however, or number of bits, will still be no more than N^2,
i.e. a polynomial in N. (If we want to allow varying connection strengths,
we could assume that 100 bits, or about 30 significant figures, are enough
to represent each different strength as a real number, to give 100*N^2,
still a polynomial in N.)

>The problem of TIME of course plays a large role in how we came to be
>put together as we are: lots of individually weak processors rather
>than a few very powerful ones. I brought up this ADDITIONAL issue 
>because it was not clear to me before, and still remains unclear,
>that human beings could be imitated by Turing machines EVEN IF WE
>FORGET TIMING. We make not only connections but new neurons, each
>of which is one of those individually weak processors. That does not
>look to me like the kind of thing that Turing machines could easily
>imitate.
>
You may well be right about "easily" (this is a relative term though). But
of course a computer can at least simulate the creation of other computers
or processing elements in its software, assuming it has unlimited memory, or
can get more memory when needed. It doesn't have to physically manufacture
new structure. 

Best to all,
Mike Perry

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