From: Adam Safron (asafron@gmail.com)
Date: Mon Mar 03 2008 - 07:37:17 MST
Ross,
Can you please elaborate on what you mean by determinism? If you mean
what I think you mean, that past state-descriptions contain the
information for present and then future state-descriptions, then the
brain is probably a deterministic system. Even if quantum computation
is important for cognition––which it most likely isn't––then brain
could still potentially be thought of as deterministic, depending on
your favored interpretation of quantum mechanics.
But more importantly, neurons are perfectly capable of supporting
complex processing/behavior without quantum computation: complex
patterns of action potentials in large numbers of neurons, vast
numbers multiple kinds of synapses that change their strengths with
experience, higher-level processing structures such as limbic nuclei
interacting with a columnar organized cortex; we're still figuring out
the specifics of how this all works together, but there probably isn't
a significant role for quantum effects in influencing the flow of
information in our neural systems. Quantum computation in neurons is
unnecessary to explain behavior/cognition and the theory relies on
speculative mechanisms that have not been empirically demonstrated and
seem unlikely a priori.
Question on quantum physics: My background is in neuroscience, so I'm
certainly not in a position to have strong opinions on this matter,
but I've always been baffled by the quickness with which people
conclude ontological indeterminacy from epistemological
indeterminacy. If measurement is uncertain/whacky at the quantum
level, then doesn't that limit the strength of conclusions we can draw
about the ontological status of quantum phenomena? Couldn't the
quantum systems be just as deterministic as classical systems, but
we're unable to properly measure all of the relevant variables?
Best,
-adam
On Mar 2, 2008, at 6:35 PM, Krekoski Ross wrote:
> Yah, the argument regarding the degree, or lack of degree of
> interaction that quantum effects have on a more macro level I
> suppose holds quite well. My curiosity was somewhat two-pronged --
> firstly, are current models regarding the complexity and processing
> power required for a reasonable simulation of the human brain
> adequate (ignoring the necessary overhead that a software
> implementation would entail), and secondly, a more general curiosity
> regarding the degree of determinism implied if all human reasoning
> is computable.
>
> summarizing penrose's argument:
>
> assume that my reasoning capabilities can be simulated by formal
> system F. for every statement S of F that I determine true, S is a
> theorem of F, and vice versa. Since I believe F describes my
> reasoning, I believe F is sound. Since F is sound, G(F) (goedel) is
> true, but not a theorem of F. however, since F is sound, G(F) is
> also true. However, G(F) is not a theorem of F, but I know it to be
> true, therefore F does not describe my reasoning.
>
> Rgds,
>
> Ross
>
>
> On Sun, Mar 2, 2008 at 11:03 PM, Adam Safron <asafron@gmail.com>
> wrote:
> Ross,
> Quantum entanglement is not considered to be an important factor by
> most well-regarded neuroscientists.
> With ~100 billion neurons and 10^14 synapses, the brain is plenty
> complex to explain human cognition/behavior without resorting to
> exotic physical properties. And more importantly, no one has come up
> with a reasonable account for how quantum entanglement would impact
> information processing. Quantum explanations for the mind are both
> unnecessary and unhelpful.
> -adam
>
>
> On Mar 2, 2008, at 5:09 PM, Krekoski Ross wrote:
>
> > Why has there not been any discussion that I can find, regarding the
> > very real possibility that quantum entanglement plays a large role
> > in the functioning of the human brain?
> > It certainly is a factor in the low-level motion of particles, and
> > in a chaotic system where local disturbances can lead to large
> > systemic changes, such as cascade effects in neurons, it seems to be
> > a significant oversight to not at least acknowledge it's likely
> > presence. It has significant implications for the processing
> > capacity of the human brain since it multiplies the number of
> > interactions by a significant number of orders of magnitude, and is
> > also quite relevant therefore in talking about at what point we have
> > the machine capacity with current architecture to begin to simulate
> > things.
> >
> > Rgds
> >
> > Ross
>
>
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