X-Message-Number: 23984
Date: Sun, 25 Apr 2004 07:09:19 -0400
From: Thomas Donaldson <>
Subject: CryoNet #23972 - #23983

For Mike Perry!

Some brief comments to your message in reply to me. 

Yes, I am well aware of computing devices which can act like primitive
animals etc. I was discussing the relevance of Turing's ideas to
such future devices. It isn't clear at all just how relevant Turing is
to understanding how human brains work. For that matter, it's now 
generally believed by neuroscientists that our memories CONSIST OF
the connectivity of our brains at a small scale. Not only do we grow
new connections and sometimes new neurons, but if we did not we could
remember nothing and completely fail to function. This growth of new
connections isn't a minor detail, its essential to how brains work.

As I also said, I was not arguing against the existence of MACHINES
which could imitate human beings, but against the existence of COMPUTERS
that could imitate human beings. We may well devise a machine able to
work like a brain; it seems to me, from the way in which our memories
work and other factors we've discussed before, that it would at least
be extremely difficult to devise a computer which acted in the same way,
and may be impossible. Yes, there are right now computer parts which
work by eliminating certain circuit paths within them; when we have such
parts that can also grow circuit paths within themselves the prospects
for making a machine working like a human brain will look much better.
(And note one basic problem: even on a small scale, the total number
of possible paths is factorial of N, where N is the number of nearby
neurons, at least 1000 if not more. It's not practical to implement 
such a part simply by including all possible paths and opening some
of them to substitute for growth).

And I'll end this message with another comment bearing quite directly
on cryonics: unlike freezing, vitrification will preserve the connections
Even if vitrification damages our brain cells in other ways, and we'll
need some kind of nanotech to fix that damage, then, unlike freezing
which may actually destroy some memories, we'll know that our memories
will remain. And of course this happens precisely because our memories
consist of our brain connectivity.

                  Best wishes and long long life to all,

                        Thomas Donaldson

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