From: Jeff L Jones (email@example.com)
Date: Mon Mar 03 2008 - 21:05:08 MST
I think it's also worth mentioning that even if quantum randomness
does somehow get amplified, it would just mean that some of the inputs
to the neurons are random number generators. We already have plenty
of classical algorithms that can generate pseudorandom number
sequences... and it seems very unlikely that the actual behavioral
function of the brain would care whether the sequence is truly random
or pseudorandom. This isn't cryptography where someone is trying
desparately to predict the numbers in the sequence... it's just using
it as noise to spur creativity.
My assessment is that it's possible that quantum randomness plays some
indirect role in neural activity... enough to say that the brain
behavior is not "deterministic" in its current implentation, but most
likely it plays little enough role that it's going to be deterministic
for all "practical purposes" anyway. And even if it does play such a
role, the non-determinism is just an accident of implementation and
can be simulated effectively with a deterministic computer. The much
more speculative statement that the brain may rely on some kind of
actual quantum computation (coherent superpositions large enough to
really matter at the neural level of structure) I find extremely
unlikely and borderline absurd.
On Mon, Mar 3, 2008 at 6:37 AM, Adam Safron <firstname.lastname@example.org> wrote:
> 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
> 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.
> On Sun, Mar 2, 2008 at 11:03 PM, Adam Safron <email@example.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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