by R. F. Streater.

Critique of Why classical mechanics cannot naturally accommodate conciousness but quantum mechanics can, by Henry P. Stapp.

We argue that Stapp has made three errors, one in each of the subjects of classical mechanics, quantum mechanics and experimental brain dynamics. Together they make his version of brain theory a lost cause.

Stapp wants a model of the brain which `can bring the information
together from far-apart locations' instantaneously to get the `whole thought'.
However, whole thoughts are **NOT** arrived at instantaneously; this is well known;
see for example, *Science Through a Looking Glass*, by
E. B. Davies, OUP, 2004.
By measuring brain activity and asking the subject what he is thinking,
it can be seen that one collects one thoughts from
various parts of the brain, and that this activity starts about 1/2 second before
the concious part of the brain is aware of the thought or decision.
We do not need any information to flow at the speed of light to explain these
facts; we certainly do not need any effects that travel faster than light.
Yet this is put as one of the failings of classical mechanics: it does not allow
faster than light flows of information.

He first (in 2.6) tries to model the brain as the aggregate of a large number of
spatially localised computers, each in some configuration. The (discrete) dynamics
is given by local update rules involving the state at a point and the neighbouring
points, with no interaction taking place instantaneously over long distances.
Thus his idea is to describe the brain as a field taking any of a set of finite
values at each point. He says in (2.7), `...the information stored in any *one*
[original italics] of the logically independent computers ...is ...minimal: it is
no more than is needed to compute the local evolution. This is the analogue of
the condition that holds in classical physics'. This is a deficient description
of classical physics. Firstly, he does not distinguish between the fields (the
observables) and the states (the probabilities that a certain configuration
is realised). Indeed, it is clear that he does not allow a probabilistic
description of the state, even though the brain is very noisy, and all the leading
models in the subject of neural nets use (classical) statistical physics.
But if his description is non-random, what does he mean by saying that the
computers are `logically independent' of each other? Does he mean `statistically
independent'? He gives a hint. In (2.4) he uses the analogy of a display
of pixels on a TV screen as the state of the computer. He writes that
his requirement, termed `minimal information', gives rise to
an `intrinsic description without any explicit relationship that might
exist between the elements, [such as] that Pixel 1000 has the same colour as
Pixel 1256'. Now, in a non-random description by a configuration, the
state of each pixel is
determined, as is the question whether it has or has not the same value as another
specified pixel. If this information is missing, it must be because the writer
has lost it, by replacing the (pure) state by a mixed state,
the product of probability measures at each site. For such
a state, one may
indeed say that the computers are statistically independent, and that the state
shows no correlation between different sites. It is the presence of such
correlations in quantum theory that entices the author to invoke quantum theory.
However, the author is quite wrong to suppose that classical field theory cannot have
states with correlations. The original description by pure states has got such
information contained in it. But even in a random theory, we can have correlations
between the sites, and this will occur if causal effects are present: if a cascade
of firing neurons causes others in its path to fire, then at a later time, there
will be positive correlations between the firing rates at separated points in
the brain. These can be read (slowly) by other parts of the brain, and the info
they hold summarised in a new register, forming the `whole thought'. Correlations
have been studied both theoretically and experimentally by
Valeria del Prete.

The concept that the author describes, a pure configuration of the brain containing no information about the relations between different points, does not exist in classical mechanics.

I have explained on another page
that the alleged non-locality shown by the *EPR* experiment
should be called `contextuality' in classical mechanics, and that quantum theory
does not suffer from this. I argue that when a commuting set of observables is measured,
the interpretation of any correlations must be the same as in classical probability theory.
There, it is well known that a correlation
between two observables does not imply a causal relation in either direction.
Stapp contradicts this in his Appendix
D4a as follows:

"Orthodox quantum field theory in its covariant form...is non-local in the
sense that for certain systems...the set of correlations predicted by quantum
theory ...is incompatible with the following `locality' condition: the result
of any possible measurement *M* must be independent of any free choice
that is to be made *later*...One *cannot* assume that there is no
faster-than-light influence of any kind.

So Stapp is saying (without mentioning me by name) that most of my web-site is wrong. I think this allows me to say that, no, it is he that is wrong; see my page of good cures.

Again, in Appendix 4b, Stapp writes "It [QM] is non-local in...that any...
collapse of the wave-function ...changes expectation values all over the universe".
As I have explained in my page on *EPR*, the act of
A = Alice by
measuring a local observable (but not yet reading the pointers) has no
effect whatever on Bob's observables, if they are space-like to the
measuring apparatus. On reading the pointers, Alice conditions her
state by using Bayes's theorem. This gives her updated information on her
*INFORMATION ALGEBRA*, which is the quantum version of information
set used in game theory. Since this info cannot be passed to B
until later, it does not affect his state at all. So Stapp has failed
to distinguish information available to Alice but not to Bob. The collapse
of Alice's wave function is nothing other than the application of Bayes's theorem.
To suggest that Bob's statistical description must change just because
Alice has some info, is incorrect, and would give the wrong results also in
classical game theory. For example, consider a game of cards between two players,
in which each player had a hand unseen by the opponent; it is absurd to say
that when one of them, Alice, finds that her hand includes the ace of spaces,
so the other, Bob, immediately alters his assessment of the likelihood
that this is so. Alice's measurement merely reveals the situation to her; it does not cause
any change in Bob's hand or strategy. I maintain that information obtained by
measurement in quantum theory cannot be passed faster than light,
and that information held in various parts of the brain needs time
to form a whole thought, decision or idea, just exactly as is observed (especially
at my age).

Go to **MY HOME PAGE** for references and links to
my papers and books on quantum field theory and statistical physics.

© by Ray Streater, 16/3/2004.