X-Message-Number: 11488
Date: Tue, 30 Mar 1999 02:37:17 -0700
From: Mike Perry <>
Subject: "Real" vs. simulated consciousness, etc.

Bob Ettinger, #11480, writes
...
> Of course, the strong AI people and uploaders will retort that a simulated
>digestive process will indeed perform digestion--of simulated food for
>simulated people. But they are simply reiterating their mantra that
>isomorphism indeed IS everything, that nothing matters except development of
>patterns of information, the "information paradigm"--an unproven article of
>faith, moderately plausible but no more than that.
>
Actually (and I may as well admit to being a strong-AI person, which I am),
the thought that occurred to me is that, indeed a simulated stomach does not
do the same thing as a real stomach (except relative to a simulated
environment). I'll concede that it isn't really doing digestion! But, on the
other hand, suppose we simulated a human brain. If our simulated brain is
composing poetry or solving a math problem, then clearly the simulation is
*really* doing these things and not just "simulating doing them". If our
similated brain is experiencing consciousness, is this "real" consciousness
or not? I.e. is consciousness more like digestion or more like problem
solving, or neither? I would vote for it being "real" consciousness in any
case. Subjective experiences are not tied to our physical world in the same
way as chemical processes like digestion.

>Searle's blind spot seems to be his failure to notice that many of the signals
>in our brains are "merely" symbols of certain events or conditions, either
>external or in other parts of the brain. ...
>
I think there is another blind spot too. Searle talks about machines that
manipulate "symbols." At a basic level, though, it isn't symbols but quanta
that are manipulated, albeit inefficiently and stupidly by our machines
today. But the future will, by indications, increasingly tell a different tale.
...
>One gross error which I did not
>notice Searle mention was Kurzweil's repeated statement--conveyed as fact,
>not minority opinion--that quantum decoherence requires a CONSCIOUS
>observer, not just an interaction.
...
Yes this is an error. Under many-worlds no conscious observer is required
for decoherence.
 
>As far as I recall, neither Kurzweil in this book nor Searle in various
>writings have dealt with David Deutsch's put-down of Turing computers
>(including all present digital computers)--that they are classical, while the
>real world is quantum. Can a classical system simulate events in a quantum
>world? To some extent, obviously yes, since scientists do use computers, and
>even hand calculations, to derive quantum results, and the rules of quantum
>mechanics now in use are written in classical language.

I'm not an expert here, but the consensus on this question seems to be that
classical computers *can* emulate quantum computers (and quantum systems
more generally), but only inefficiently, i.e. they will take exponential
time for some operations that the quantum computer can do in polynomial
time. On the other hand, the quantum computer itself is less powerful in
this respect than the so-called nondeterministic Turing machine, which has
the magical ability to generate copies of itself as it goes through its
computations, creating a population explosion of parallel devices which can
independently attack a problem and communicate their findings to each other.
Nothing closely approaching the NDTM has been built and may never be. But
aside from efficiency considerations, the plain old Turing machine has the
same computational power as the mighty NDTM. And the two devices bracket the
quantum computer efficiency-wise, as I've indicated. Deutsch seems to be
arguing in one place in his book that the quantum computer is actually more
powerful, computationally, and not just efficiency-wise, than a classical
Turing machine. Deutsch says this is shown in the secure communication
channel, which no classical computer or device could accomplish. But this is
something of a misunderstanding. Yes, classical devices could not do this,
but a classical computer could still emulate a virtual reality with a
sescure communication channel, though again it might be inefficient.

>But one suspects that
>any attempt actually to emulate a person, or a significant part of the real
>world, with a Turing machine would sooner or later run into insuperable
>problems, if indeed there were not insuperable conceptual problems at the
>outset, as I have discussed elsewhere.
>

My understanding is, again, that the big problems will be those of
efficiency, not theoretical computing capacity. We may find that, for
practical purposes, classical computers can't emulate persons because of  an
exponential time requirement--which, however, quantum computers can overcome.

Mike Perry

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