X-Message-Number: 26086
Date: Mon, 25 Apr 2005 11:41:48 -0400
From: Francois <>
Subject: For Thomas

Yes, your discussion was accurate.

One point you, and others, bring up is the difference between simulated and
real objects. I would like to describe a setup that may shed a different
light on the problem. In the 19th century, Charles Babbage drew blueprints
on what we recognize today as a programmable mechanical computer. He even
started building it but it was never completely finished. The machine did
with levers, gears and cams what our computers do with semiconductors, it
was really quite ingenious.

It would be fairly easy today to program a 3d model of that machine in a
modern computer. We could then watch it go through it's mechanical computing
process on a video monitor, gears turning, cams pushing, levers flipping,
etc. In fact, if we made the model visually good enough it would be nearly
impossible to tell if what we are watching on the screen is a picture of a
real machine or a rendering of the computer model. Still, the model is just
a bunch of 0's and 1's being manipulated by the real silicon computer, so it
cannot be said to be "real", although it can do "real" computations. The
output it comes up with for a given input is the same as what a real Babbage
machine would give us.

Lets now imagine a similar setup, but this time the thing being modeled will
be a complete human. We assume that we have a really powerful computer of
the Turing type, and our model will have a detailled representation of each
individual atom in that human. The computer will accurately manipulate these
atoms and molecules according to know laws of chemistry and physics. We also
provide this simulated human with some environment which can be much
simpler, a well rendered modern videogame arena for example. On our
videoscreen, with enough magnification, we see atoms and molecules doing
what real atoms and molecules do, moving around, colliding, coming apart,
forming new molecules, etc.

Moving back a bit, we should see what appears to be a human moving around in
the game arena. All of his simulated atoms behave like real atoms in the
real world, in the same fashion as the simulated gears of our Babbage
machine model behaved like real ones. The simulated human should therefore
provide similar outputs for similar inputs. We could, for instance, talk to
him, using a microphone to send a digital version of our voices in his
simulated world. He should be able to reply in a perfectly plausible way,
with questions, answers and comments going back and forth as in any normal
conversation between two real humans. Even though he would still only be a
bunch of 0's and 1's being manipulated by our powerful digital computer, our
simulated human would display all of the behaviors we would expect from a
real one, including self awareness.

Or would it? There is one aspect of the real world that a Turing type
computer cannot deal with, and that's the quantum behavior of particles.
Atoms are large enough and massive enough for their quantum nature to be
ignored in most instances, but not all. Is this an important factor in the
workings of our brains? It's a question we don't have an answer to right
now. If it is though, it doesn't mean that simulating a human is impossible,
it would only mean that simulating a human on a Turing type computer is
impossible. At any rate, simulating a human in this way, even if it was
possible in principle, would be a stupid way to do it. In making a 3d model
of a Babbage machine we do not have to keep track of every individual atom
of iron, copper and zinc in its steel and brass components. We model the
parts themselves, not the atoms they are made of. Similarly, we would not
have to keep track of every neurotransmitter molecule released by a synapse,
all we need is define the size, shape and motion of the resulting droplet. A
model made following this principle would still be a massive undertaking but
it would not be out of reach. It's an experiment worth doing, because it
will teach us a lot regardless of the outcome.

The Devil fears those who learn more
than those who pray

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