On 8/2/2011 2:08 PM, Stephen P. King wrote:
On 8/2/2011 4:04 PM, meekerdb wrote:
On 8/2/2011 12:43 PM, Craig Weinberg wrote:
On Aug 2, 2:06 pm, "Stephen P. King"<[email protected]> wrote:
The point is that there is a point where the best possible
model or
computational simulation of a system is the system itself. The fact
that
it is impossible to create a model of a weather system that can
predict
*all* of its future behavior does not equal to a proof that one cannot
create an approximately accurate model of a weather system. One
has to
trade off accuracy for feasibility.
I agree that's true, and by that definition, we can certainly make
cybernetic systems which can approximate the appearance of
consciousness in the eyes of most human clients of those systems for
the scope of their intended purpose. To get beyond that level of
accuracy, you may need to get down to the cellular, genetic, or
molecular level, in which case it's not really worth the trouble of re-
inventing life just to get a friendlier sounding voicemail.
Craig
So now you agree that a simulation of a brain at the molecular level
would suffice to produce consciousness (although of course it would
be much more efficient to actually use molecules instead of
computationally simulating them). This would be a good reason to
say 'no' to the doctor, since even though you could simulate the
molecules and their interactions, quantum randomness would prevent
you from controlling their interactions with the molecules in the
rest of your brain. Bruno's argument would still go through, but the
'doctor' might have to replace not only your brain but a big chunk of
the universe with which it interacts. However, most people who have
read Tegmark's paper understand that the brain must be essentially
classical as a computer and so a simulation, even one of molecules,
could be quasi-classical, i.e. local.
Brent
Hi Brent,
I wonder if you would make a friendly wager with me about the
veracity of Tegmark's claims about the brain being "essentially
classical"? I bet $1 US (payable via Paypal) that he is dead wrong
*and* that the proof that the brain actively involves quantum
phenomena that are discounted by Tegmark will emerge within two years.
We already have evidence that the photosynthesis process in plants
involves quantum coherence, there is an experiment being designed now
to test the coherence in the retina of the human eye.
http://www.ghuth.com/2010/02/03/another-finding-of-quantum-coherence-in-a-photosynthetic-biological-system/
http://www.ghuth.com/2011/04/24/quantum-coherence-and-the-retina/
Those are not really to the point. Of course the brain involves quantum
processes and some of these involve coherence for short times. But
Tegmark argues that the times are too short to be relevant to neural
signaling and information processing. There's an implicit assumption
that neural activity is responsible for thought - that the 'doctor'
could substitute at the neuron level. I think this is right and it is
supported by evolutionary considerations. We wouldn't want an
intelligent Mars Rover to make decisions based on quantum randomness
except in rare circumstance (like Buridan's ass) and it wouldn't be
evolutionarily advantageous for an organism on Earth. I'm glad to
accept your bet; except that I'm not sure how to resolve it. It don't
think finding something like the energy transfer involving coherence in
photosynthesis or photon detection is relevant.
As to your post here. Craig's point is that the simulated brain,
even if simulated down to the molecular level, will only be a
simulation and 'think simulate thoughts'. If said simulated brain has
a consiousness it will be its own, not that some other brain.
Craig's position seems to be more a blur than a point. He has said that
only biological neurons can instantiate consciousness and only a
conscious being can act like a conscious being. That would imply that a
being with an artificial, e.g. silicon chip based, brain cannot act like
a conscious being.
A consciousness can no more be copied than the state of a QM system.
That's the point in question. If Tegmark is right, it can.
Brent
Onward!
Stephen
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