Re: [asa] Brain and Determinism (fwd)

Just briefly because I am on the run today, JP&NB seem to be making an
argument based on classical physics, not QM. They indicate classical
physics shows some things are non-deterministic.

Where is this going and why should we care? Minds, being based on brains,
brains being based on hypercomplex analog processes, exhibit
non-deterministic characteristics. This is new to me, having never thought
about it before.

Thanks,
Dave C

On Thu, Oct 1, 2009 at 4:03 PM, Bill Powers <wjp@swcp.com> wrote:

> Forwarded to ASA on behalf of Merv:
>
>
> I will happily reply here as best I can, exposing my own ignorance when it
> comes
> to Planck lengths or quantum uncertainties -- and hoping that then some of
> the
> real physicists can step in and clarify for both of us. Here goes...
>
> Regarding ontological vs. epistemological uncertainties first: I think I
> understand your confusion on this since it is the same confusion I am
> emerging
> from. I used to think that the Heisenberg uncertainty principle was no
> more
> than a statement of a limitation on what we could find out about a small
> particle. I.e. Any instrument will affect what it is measuring -- a
> thermometer slightly changes the temperature of a liquid, a volt-meter will
> slightly alter the circuit in which it is connected to get its voltage
> reading,
> etc. So that's easy! (I used to think.) The electron can still be in a
> precise
> place, have its simultaneously precise velocity and all, and we just aren't
> able
> to measure those things since any instrument would massively affect the
> particle. So I was able to preserve my notion of ontological determinism
> by
> thinking "*In principle* the electron does have a precise location and
> velocity
> --even if we can never know both with infinite precision." (and come to
> think
> of it, we could never know anything with infinite precision anyway.) But
> our
> lack of knowledge doesn't make it not so any more than my lack of knowledge
> about where you are right now would make your location be indeterminate.
> But
> physicists come along and tell me "not so fast!" Actually, the uncertainty
> principle runs deeper and informs us that the electron's simultaneous
> position
> and velocity are indeterminate *even in reality*. I.e. there are no
> simultaneously precise values to known *even in principle*! Not even by
> God.
> This is what apparently defeats the notion of ontological determinism even
> though I can't wrap my mind around it. It is philosophically a much
> different
> and more bizarre ball game than merely saying "we can't know it."
>
>
> Regarding Planck lengths, I too would love to know more about this. But
> from
> what I've gathered it represents a "smallest possible" increment in space
> that
> would be astronomically smaller than a proton. (Probably having to do with
> how
> far light could travel in a Planck instant). It is apparently the smallest
> "unit?" of length anything could actually have. To my already fried
> imagination, this has the effect of "digitizing" space. Just as we can
> recognize the digitized and pixelated graphics of an object "moving" across
> a
> computer screen, now I imagine a pixelated space where things "lurch along"
> from
> one Planck length to the next without being able to exist in between. How
> this
> fits with classical Newtonian notions of momentum or inertia I would love
> for
> somebody else to explain to me. A digitized motion where something is
> pausing
> at a new quantized location on your screen for 1/30 of a second before it
> is
> instantaneously relocated to the next position is not at all the same as
> "continuous" motion where inertia is preserved. But if Planck lengths and
> times
> are ontologically accurate descriptions of reality, maybe there is no such
> thing
> as "continuous" motion? George, ... somebody? ..... help!
>
> --Merv
>
>
>
> Quoting Bill Powers <wjp@swcp.com>:
>
> Merv & David:
>>
>> A few comments.
>>
>> First, I don't understand the seemingly discontinuous comment about the
>> Planck length.
>>
>> Second, I don't follow the argument. It seems to me that from beginning
>> to end they are discussing epistemological uncertainty and not
>> ontological uncertainty. In fact, it seems to me that the Heisenberg
>> uncertainty can be similarly interpreted.
>>
>> Since I don't consider the Heisenberg uncertainty to really get at the
>> matter (it can be viewed as merely the result of not attempting to
>> measure an eigenvalue), consider instead something like the decay of a
>> radioactive nucleus.
>>
>> We are told that if one were to ask why this particular nucleus decayed
>> at this instance that the "appropriate" answer is that there is no
>> reason. Yet, we are also told that the statistical decay of a host of
>> such atoms has such a small variance that we can make extremely accurate
>> atomic clocks from them.
>>
>> The situation is analogous to tossing an honest penny. If one were to
>> try to predict whether this penny on this toss would be a head or a
>> tail, our knowledge would be completely uncertain. All we could say is
>> that it will be either a head or a tail. And this is why we in Bayesian
>> fashion say that the result is 50-50, a measure of complete ignorance.
>> Yet, were we to toss 10^23 such coins we could predict with
>> extraordinary accuracy the fraction of coins that are heads and the
>> fraction that are tails.
>>
>> In this analogical story would we say that there was no reason that the
>> flip of a single coin came up heads? I don't think so. Such a story
>> was well known long befor QM came along, and no one was led to argue
>> that we live in a random universe. Well, maybe not no one. It was
>> probably a common belief prior to the advent of modern science.
>>
>> I know that what I'm suggesting seems to lead to hidden variables. I've
>> just never quite understood the claim that we live in a random universe,
>> which appears to imply what?
>>
>> Is a random universe that is unpredictable? That's epistemological.
>> Ontologically, it must mean something like events occur for no reason
>> whatsoever, and yet they are statistically deterministic. This appears
>> to me, at least, to be a paradox. Does ontological randomness entail
>> that events occur without any antecedent conditions, not just
>> unobservable, but none whatsoever. Even with the pennies there are
>> antecedent condtions: the penny must be tossed.
>>
>> In summary, I don't get Polkinghorne's argument. Please, explain.
>>
>> thanks,
>>
>> bill
>>
>> On Thu,
>> 1 Oct 2009,
>> mrb22667@kansas.net wrote:
>>
>> My comments injected below...
>>>
>>> Quoting David Clounch <david.clounch@gmail.com>:
>>>
>>>
>>>> Polkinghorne and Beale write about determinism and the
>>>> brain1<#sdfootnote1sym>
>>>>
>>>>
>>>> Consider a single nitrogen molecule in the air you are now breathing.
>>>> On
>>>> average it is traveling 450 m/s and bounces off about 7 billion other
>>>> air
>>>> molecules every second, thus 7,000 every microsecond. Suppose you knew
>>>>
>>> the
>>
>>> exact position and momentum of every one of these particles (even though
>>>> this is impossible by Heisenberg's uncertainty principle), then perhaps
>>>>
>>> you
>>
>>> could, at least in principle, predict exactly where that nitrogen
>>>>
>>> molecule
>>
>>> would be one microsecond later. Of course there are all kinds of
>>>> complications, such as electrostatic forces, angular momentum, and so
>>>> on,
>>>> but lets make it simple and pretend that these were all perfect spheres
>>>>
>>> and
>>
>>> Newton's laws exactly applied – the kind of eighteenth-century
>>>>
>>> worldview
>>
>>> that shaped the Enlightenment and still influences much of our thinking.
>>>>
>>> But
>>
>>> suppose a tiny error is introduced in the angle at which this air
>>>>
>>> molecule
>>
>>> is traveling, for any reason at all. A little bit of uncertainty about
>>>>
>>> the
>>
>>> position of an electron, say. Call this error ï ¥(epsilon). After one
>>>> collision, the error is 2 ï ¥; after two collisions 4 ï ¥, and so forth.
>>>> Each
>>>> microsecond this error will increase by 2^7000, or roughly 10^2100. The
>>>> situation is clearly hopeless even if the initial error corresponds to a
>>>> Planck length (1.6 x 10 ^ -35 m – the smallest possible length, at
>>>>
>>> which
>>
>>> conventional physics breaks down) per meter, after just 97 collisions the
>>>> uncertainty will be enough for the position of the molecule to be out by
>>>> more than the diameter of a nitrogen molecule (6.2 x 10^-10m), which
>>>>
>>> means
>>
>>> it will miss the 98th target. This will happen in less than a 70th of a
>>>> microsecond. And making the error one Planck length in the size of the
>>>> observable universe (about 3 x 10 ^23 m) just means it will miss the
>>>> 176thmolecule. So even with the unrealistic assumptions of a perfect
>>>> Newtonian
>>>> world elsewhere, exact determinism is dead.
>>>>
>>>
>>> It isn't the error amplification (chaos theory) that kills determinism.
>>>
>> Because
>>
>>> the original 18th century thought assumed up front that such knowledge
>>> was
>>> impossible anyway, they had already premised their speculation as being
>>> so
>>>
>> *in
>>
>>> principle* since they knew nobody could know all this. And that caveat
>>>
>> allows
>>
>>> them (and us now even with Chaos theory) to reduce the initial state
>>> error
>>>
>> *in
>>
>>> principle* to zero (infinitely smaller than a Planck length). So it is
>>>
>> only the
>>
>>> Heisenberg uncertainty as mentioned below that actually drives the real
>>>
>> stake
>>
>>> into the heart of determinism. Yet for all this, it doesn't prevent some
>>>
>> from
>>
>>> still thinking deterministically about the universe as a strictly causal
>>>
>> domain.
>>
>>> Since my mind can't fully fathom the nature of our ontological
>>> uncertainty,
>>>
>> I
>>
>>> find myself in this deterministically minded camp at least every other
>>>
>> Thursday.
>>
>>> Maybe the atoms in my brain will happen to bounce that way today.
>>>
>>> --Merv
>>>
>>> In fact, of course, we use
>>>> statistical mechanics to describe the behavior of gases and liquids and
>>>>
>>> do
>>
>>> not try to predict the behavior of individual small molecules. But many
>>>> people think of the indeterminacy in statistical mechanics as simply a
>>>> limitation on our knowledge rather than a reflection of real
>>>>
>>> indeterminacy
>>
>>> as in the quantum world. This kind of argument strongly suggests, to our
>>>> satisfaction at least, that in cases like the movement of molecules in
>>>>
>>> air
>>
>>> the indeterminacy is real.
>>>>
>>>>
>>>> They go on to describe calcium ions in te synapses in the brain, and
>>>> use
>>>>
>>> a
>>
>>> similar analysis. They conclude:
>>>>
>>>>
>>>> We will see later that this entirely destroys the idea that the brain
>>>> is
>>>>
>>> a
>>
>>> fully deterministic system.
>>>>
>>>>
>>>>
>>>> 1 <#sdfootnote1anc>Questions of Truth, pp. 126-127
>>>>
>>>>
>>>
>>>
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>>>
>>>
>

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Received on Thu Oct 1 17:39:47 2009