X-Message-Number: 3846
From:  (Thomas Donaldson)
Subject: Re: CryoNet #3801 - #3811
Date: Tue, 14 Feb 1995 14:22:38 -0800 (PST)



Hi again!

I know this reply is a bit late, but I don't access the net every day and
for several weeks I've been busy with several other things. 

But a few more words on uploading might help:

First, it's probably true that we could make a computer capable of reacting 
just like a person. In that sense, simulation would be possible. But for 
actually copying a real person, you need more than that: you need a system
which works equally fast as a real person. That is where the difficulties
really arise: think of neurons not as single objects which send YES-NO
messages but as objects which themselves are small "computers", and respond
to many different messages both electrical and chemical. And then notice
that we have millions of them, all working in parallel. That is what makes
the problem hard.

Second, a need for operation at least as fast as a human being (note that
in many cases computers still can't equal that!) requires parallel computing.
ie neural nets of some kind. These neural nets will, of course, require
physical connections between them ... whereupon we find ourselves with the
problem of making such nets so that new connections (not in computer software
that simulates the system, but in the actual physical system) can be inserted
easily... or otherwise created. 

I do not wish to claim that we will never be able to create such a machine.
But current electronic implementations of computers don't do well in growing
new connections ... physically, not in simulation. Any simulations, of course,
must also deal with message passing by chemical means, too. 

Third, there is entirely too much mythology about this uploading. That 
mythology (and I'm hardly the first person in this discussion to raise this
issue) makes it hard to argue against uploading for those who believe in it. 
They don't want to be uploaded in any present computer: not a Cray, nor an 
nCube, nor a Connection Machine, nor any others, even the fastest now 
known. They want to be uploaded into some IDEAL computer which by definition
has all the features required: large enough memory, fast enough to make a 
real-time simulation, etc etc. The only computers we know of which are 
presently capable of emulating human beings in real time are known as human
brains. They also seem to do a good job of it... no one would claim perfection,
but a good job.

If those in favor of uploading were to start thinking carefully about what
their ideal computer must do, then we may get somewhere. If it remains simply
a matter of definition, definitions don't prove that the defined object 
exists or even CAN exist. Nor, as I and others have said, does Turing's Theorem
tell us anything useful for this problem. We are asking for a computer which 
doesn't just perform the calculations needed to think and to guide its attached
body, but does them IN REAL TIME ie. as fast as we do. Turing never really 
grappled with this problem. It would be nice if some advocates of uploading 
were to do so. So long as we can simply ASSUME the possibility of this 
ideal computer, there would be no argument at all. 

			Best and long long life,

				Thomas Donaldson





   
 



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