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Article 1404 of comp.ai.philosophy:
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>From: weemba@libra.wistar.upenn.edu (Matthew P Wiener)
Newsgroups: comp.ai.philosophy
Subject: The limits of quantum simulation
Message-ID: <56836@netnews.upenn.edu>
Date: 19 Nov 91 15:05:45 GMT
References: <1991Nov13.003616.1135@ucunix.san.uc.edu> <91Nov15.131947est.8261@telos.ai.toronto.edu> <277@tdatirv.UUCP>
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Reply-To: weemba@libra.wistar.upenn.edu (Matthew P Wiener)
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In-reply-to: sarima@tdatirv.UUCP (Stanley Friesen)

maione@ai.toronto.edu (Ian Christopher Maione) wrote:
>> [...]  In addition, even a simulation of the brain on a digital
>> computer is impossible if quantum level effects are in any way
>> significantly involved in its operation (see Roger Penrose, "The
>> Emperor's New Mind").

This gets the usual simulation response:

In article <73NiBB2w164w@elrond.toppoint.de>, freitag@elrond (Claus Schoenleber) writes:
>Why? There are possible ways to get quantum level effects even on a
>simulation.  (or simulate them...)

In article <277@tdatirv.UUCP>, sarima@tdatirv (Stanley Friesen) writes:
>Bull!  All quantum effects I know of can be simulated using a RNG!

This simulation response misses a certain subtle point.

If consciousness depends, for example, on the privacy effects of quantum
cryptography, then no simulation will achieve real-world consciousness.
A simulation using RNG's would be classical, and at best, would be con-
scious relative to other simulations.

The following example of the use of quantum privacy by conscious minds
seems--if not plausible, at least possible--on evolutionary grounds.  If
prey and predator are in a game theoretic situation whose optimum depends
on randomness, then not only does it seem easier to go straight for the
quantum randomness, the creature who evolves a classical RNG solution to
its optimum can have its algorithm cracked.

While I personally think Penrose is off the wall in claiming that
quantum gravitational effects are going to be relevant in explaining
consciousness, note that if he's right, then there is a distinct
possibility that Church's thesis itself will be invalidated.  For
the mathematics of four-manifolds contains undecidable propositions.
The right physics experiment regarding quantum gravity could then,
in principle, be an oracle for a universal Turing machine.  What
Penrose is suggesting is that *we* are such a physics experiment.
And in this case, no amount of simulation is going to achieve even
a limited consciousness relative to anything.
-- 
-Matthew P Wiener (weemba@libra.wistar.upenn.edu)


