Re: Quantum spookiness in the brain?

Ernest Major <{$to$}@meden.demon.co.uk> wrote:
In message <ftjgn9$pd1$3@xxxxxxxxxxxxxxxxx>, Paul J Gans
<gans@xxxxxxxxx> writes
Vend <vend82@xxxxxxxxxxx> wrote:
On 9 Apr, 21:27, r norman <r_s_norman@xxxxxxxxxxxx> wrote:
On Wed, 9 Apr 2008 12:08:26 -0700 (PDT), Vend <ven...@xxxxxxxxxxx>
wrote:



On 9 Apr, 19:51, r norman <r_s_norman@xxxxxxxxxxxx> wrote:
On Wed, 9 Apr 2008 16:30:42 +0000 (UTC), Paul J Gans <g...@xxxxxxxxx>
wrote:

<snip>

I believe that Penrose was dealing with what I will call
the "mechanistic view" of the mind. In that view two absolutely
identical brains will think absolutely the same thoughts and make
absolutely the same decisions.

Folks who think this are basically saying that there can be no
free will since thoughts are then totally dependent on the physical
details of the brain that thinks them.

For many, the only way out of this is to posit a supernatural
something that would allow absolutely identical brains to think
different thoughts.

Penrose, I believe, was pointing out that it is impossible to
have absolutely identical brains because of quantum uncertainty.

The rest of his thinking then took off from this point of departure.
And I agree that the rest of his thinking may be just so much
poop, but the problem of identical brains is a real one and I believe
it is solved by quantum uncertanty.

The notion that identical brains must think alike and act alike is,
indeed, logically equivalent to the notion that, given the details of
one brain, one can then compute presumably the future of what it will
do.

This assumes that the physical laws are computable, or at least can be
approximated by computable functions to any arbitrary level of
precision.
This is exactly the assumption that Penrose and Hameroff challenge.

All known fundamental physical phenomena seem to be described by
(approximately) computable laws, with the only exception of quantum
wavefunction collapse, which seems to be probabilistic.
Many interpretations of quantum mechanics have been formulated to try
to address this oddness. Some just accept it as it is while others
suggest that it might be actually a deterministic chaotic phenomenon.

Penrose and Hameroff instead suggest an interpretation where quantum
wavefunction collapse is governed by a (still unknown) uncomputable
physical law.

Their rationale for doing so is that they have convinced themselves
that certain aspects of human behavior (like mathematical intuition)
aren't compatible with a computable (and possibly probabilistic)
physics, thus they have cringed on the only not completely explained
fundamental phenomenon.

However, their argument for the non-computability of human behavior is
flawed (IMHO and in the opinion of most experts), making their
proposed interpretation unparsimonious.

I remember a time when Penrose argued that quantum gravity must be the
factor behind consciousness since it was the only part of physics left
unexplained.

Right, he thinks that when quantum gravity is explained, it will
explanation for quantum wavefunction collapse and provide the
mechanism to understand human consciousness.
If I remember correctly, his schema for explanation is:
- Particles with mass distort space-time.
- Particle quantum states can be in superposition.
- A superposition of states of a massive particle causes a
superposition states of space-time.
- When the superposed states of space-time become too much different
(respect to a threshold depending perhaps on h and c), the universe
forces the superposition to collapse towards one state of space-time
and hence one state of massive particles (and entangled mass-less
particles).

Hmmm.

I think it can be demonstrated that quantum wave function
collapse is a product of human-environment interaction.

Consider the Schrodinger's Cat Modified: We have a container
with the usual cat and random apparatus. One one side of the
container we have the usual wise observers who create a state
function for the cat that is a supersition of two states with
appropriate normalization constants.

On the other side, and hidden from the first observers by
a curtain or what have you, is another set of observers. Their
side of the container has a glass wall. Their state function
for the cat never collapses at all.

If the cat dies, their wave function does exhibit a state transition
from phi_{living} to phi_{dead}. This transition is akin to
an electronic transition.

What I am claiming, and think I have shown an instance of, is that
the wave function represents *our* knowlege of the system at any
time t. It is always a composite function to some extent, but the
more we know, the fewer terms are included.

Comments?


I subscribe to the pragmatic interpretation ("shut up and calculate") of
Quantum Mechanics - in other words for all the problems as to what QM
means, we can ignore them to the degree that QM still remains a
startingly effective theory for predicting the behaviour of the world.

As I understand the matter it is not correct to say that the wave
function represents out knowledge of the system. Experiments with Bell's
Inequality exclude, if I recall correctly, a local hidden-variable
theory - meaning that we either have to give up determinacy or locality.

I think that your invocation of Schrodinger's Cat is a red herring.
Schrodinger's Cat is a thought experiment that raises the question of
why behaviour is classical at macroscopic scales. It doesn't not allow
us to infer that the cat is neither alive or dead.

Your argument is tantamount to a claim that the wave function of a
system can be different for different observers. For an experimental
test of this I suggest the following - a linear accelerator in which
anti-protons are slammed into protons, and two particle detects at
successive points downstream of the path of the resulting particles,
each with a separate observation team. Let the antiproton energy be
tuned to produce Y-mesons. These can decay in several ways - e.g. into
an electron-positron pair, or a muon-anti-muon pair.

If you are correct then what the people observing the second detector
doesn't depend on what the people observing the first detector saw
first. Assume that for the sake of argument that each of the stated
decay paths occurs at a 50% rate. You predict that the second team will
observe a positron 50% of the time, regardless of whether the first team
observed a position or an anti-muon. I think that you will find that
this prediction is not borne out by experiment.

I know that.

But I'm not sure you've quite got it right in terms of my cat
experiment.

Consider the accelerator experiment. But this time do NOT let
the two groups communicate in any way.

The way you have set it up the two groups are communicating,
by decay particle at least. In my cat analogy (and yes, I
know why Schrodinger thought it up -- but it works the other
way around too) the two groups do not communicate at all.

As soon as they interact, they share knowlege and they get
the proper results.

Look at it another, non QM way. Let there exist a fair coin
and a device for fairly flipping it. Based on that information
alone a theoretician would state that the most probable outcome
of N flips would be N/2 heads.

An actual observer watching the flipping and noting the results
finds that there were not N/2 heads, but some nearby number.

Is there a contradiction here? Absolutely not.

In the cat experiment the standard observers are in the
role of the theoretician. They in no way intereact with
the experiment, they only hypothesize about the results.

The folks watching the cat on the other hand, have precise
knowlege.

In my opionion Bell's theorem doesn't come into play here
at all.

Of course, I may not be right about any of this...

--
--- Paul J. Gans

.

Relevant Pages

  • Re: Quantum spookiness in the brain?
    ... >>>identical brains will think absolutely the same thoughts and make ... >>>have absolutely identical brains because of quantum uncertainty. ... and hidden from the first observers by ... their wave function does exhibit a state transition ...
    (talk.origins)
  • Re: Quantum spookiness in the brain?
    ... something that would allow absolutely identical brains to think ... have absolutely identical brains because of quantum uncertainty. ... with the usual cat and random apparatus. ... either the second observer is in the box (and hence ...
    (talk.origins)
  • Re: Quantum spookiness in the brain?
    ... identical brains will think absolutely the same thoughts and make ... have absolutely identical brains because of quantum uncertainty. ... Consider the Schrodinger's Cat Modified: ... and hidden from the first observers by ...
    (talk.origins)
  • Re: Quantum spookiness in the brain?
    ... identical brains will think absolutely the same thoughts and make ... have absolutely identical brains because of quantum uncertainty. ... wavefunction collapse, ... Consider the Schrodinger's Cat Modified: ...
    (talk.origins)
  • Re: Quantum spookiness in the brain?
    ... identical brains will think absolutely the same thoughts and make ... have absolutely identical brains because of quantum uncertainty. ... with the usual cat and random apparatus. ... either the second observer is in the box (and hence ...
    (talk.origins)