Subject: The space of possibilities
Date: Wed, 07 Aug 2002 20:41:36 +0300 From: Dimi Chakalov <[email protected]> To: "Matthew J. Donald" <[email protected]> CC: [email protected], [email protected], [email protected] Dear Matthew, I quoted your recent quant-ph/0208033, "Neural Unpredictability, the Interpretation of Quantum Theory, and the Mind-Body Problem" [Ref. 1], at http://members.aon.at/chakalov/intro.html#Donald Regarding the space of possibilities, you wrote [Ref. 1]: "That space has so many dimensions and the dynamics is so unconstraining that after any deviation we should surely never expect to get back to where we would have been." I'm wondering, why did you decide to dedicate twelve years from your life to the so-called psycho-physical parallelism? It's a dead-end, I'm afraid. See http://members.aon.at/chakalov/Baars.html http://members.aon.at/chakalov/Granik.html http://members.aon.at/chakalov/Vecchi.html http://members.aon.at/chakalov/Page.html http://members.aon.at/chakalov/Penrose.html I think Pauli and Jung have explained the whole issue half a century ago, http://members.aon.at/chakalov/PHI.html#Pauli I believe have sent you my critical comments in 1999, and I'm still awaiting for your reply. No rush, take your time. Regards, Dimi
[Ref. 1] Matthew J. Donald. Neural Unpredictability,
the Interpretation of Quantum Theory, and the Mind-Body Problem. Tue, 6
Aug 2002 08:37:53 GMT,
"The wider purpose of this paper is to draw attention
to problems which could be significant in any attempt to understand the
physical underpinning of individual human awarenesses. In a long series
of previous papers (Donald 1990, 1992, 1995, 1997, 1999), I have proposed
a solution to these problems in the context of a many-minds interpretation
of quantum theory. Whatever else they might amount to, I believe that these
papers do provide a serious attempt to grapple with the kind of detailed
technical issues which are involved in a complete and consistent version
of this sort of interpretation.
"The fundamental premise is that it is not an illusion
to suppose that an individual consciousness has a past and a future, or
a range of possible futures. Given that premise, we can ask what can be
said about someone's possible future experiences and their probabilities.
It will be taken for granted here that we have full knowledge of the observer-independent
behaviour of all the physical matter involved, and it will also, of course,
be assumed that mind has no direct physical effect on matter. (...) One
of the underlying aims of the paper, therefore, is to justify the proposal
that a complete understanding of the relationship between subjective experience
and its physical correlates, and of the dynamics of that experience, does
require the introduction of mathematical definitions and indeed of new
physical laws.
"It is all very well for a relational approach to probability
(Saunders 1998) to suggest that probability should be thought of as a relation
between a present and a possible future. But such a relation depends on
a present and a future being specified. The self-observation of the brain
is a lively dynamical process, continually subject to possibilities of
growth and decay which are not easily classified.
"The fundamental problem in the interpretation of quantum
theory is to understand the states occupied (or apparently occupied) at
any moment by any physical system. Brains are physical systems and so quantum
theory calls their states and histories into question, but brains also
appear to be the systems through which all observations are ultimately
made. Understanding the act of observation therefore requires an understanding
of the physical nature of neural processing.
"In conventional terms, the evidence for mind-brain parallelism
is so overwhelming that many have argued that it amounts to an identity.
Everything we experience is directed reflected in the functioning and structure
of our nervous system. (...) Quantum physics calls all our ideas of "physical
structure" into question and seems to give a special role to the "observer".
In this context, therefore it seems sensible, at least at the outset, not
to condemn as mere naivity the separation between the ideas of mind and
of brain.
"Psycho-physical parallelism implies that the knowledge
of any individual must be reflected in his or her physical neural structure
or functioning. Individual knowledge is the foundation of all knowledge,
and so the physical structure of individual human brains underlies all
knowledge. As physical systems, brains are merely complex collections of
ions, atoms, and molecules. Ions, atoms, and molecules are quantum mechanical
systems, and so the brain is a quantum mechanical system. If quantum states
are states of knowledge then the physical structure of a brain, considered
as a quantum system, is fundamental to that knowledge. This might appear
to lead to problems of self-reference. (...) In my many-minds theory, the
possible futures of an observer, and therefore the external quantum states
he can expect to observe, are ultimately determined by what he is, rather
than by his explicit knowledge (see the discussion around definition 6.4
in Donald 1999).
"Neural firing appears to be the basis of neural functioning.
There are around 10^11 neurons in a human brain. At least as a first approximation,
biologically important information in the brain seems to be coded into
the all-or-nothing dichotomies for individual neurons of either firing
or not-firing. If we want to assign quantum states to our own brains compatible
with our own knowledge, then it might seem that a reasonable starting point
would be to assume that the current pattern of neural firing is "known".
"In fact, the precise order of neural firings is utterly
unpredictable and most of this unpredictability is due to the internal
mechanisms of neural functioning. Unpredictability at a detailed level
is entirely comprehensible in biological terms. Neural nets evolved in
order to co-ordinate rapid responses such as fight or flight. It is vital
that a threatened animal flees from a predator, but it would give a great
advantage to the predator if the flight follows an exactly predictable
path. The timing of turns and darts and lunges should always be unpredictable.
"Estimates vary, but there are probably at least 10^14
synapses in an average human brain. Neurons fire at an average rate of
order a few times per second. If every synaptic transmission is an uncertain
event with probability significantly distinct from 0 or 1, then there will
be at least 10^14 such events per second in the brain. Thus uncertainty
in ordinary everyday neural functioning may overwhelm, by many orders of
magnitude, many conventionally recognized sources of observed "quantum"
uncertainty and may, in fact, be the major source of unpredictability in
human affairs. If we interpret quantum states as states of knowledge, then
any uncertainty about what we do not know becomes a quantum uncertainty.
"How Large is the Space of Possibilities? "2^10^14 different patterns may seem high, but it is negligible
by comparison with the minimum dimension (around 10^(10^26)) of the space
of thermally active wavefunctions available to any quantum system with
the physical entropy of the brain. These numbers are both measures of the
number of possibilities at the microscopic level.
"Although our thoughts naturally
tend to be most concerned with features of our lives that we can predict
-- like what we should buy to eat for dinner tonight, or when we should
set of on a journey if we are to expect to get to a given destination by
a given time -- the unpredictable features constantly push us around in
the space of possibilities. That space has so many dimensions and the dynamics
is so unconstraining that after any deviation we should surely never expect
to get back to where we would have been.
"This seems almost inevitably to lead to the idea that
the timings of neural events need to be defined to sufficient precision
that changes in the time-orderings of each pair of spatially distinct events
can be distinguished. But since this involves an ordering of, say, 10^11
events in a second, or at least an ordering of the timelike separations
among those events, this implies a temporal precision which in biological
terms is simply ridiculous.
"Finding the Observer "So, as a preliminary model of personal "knowledge", we
can take the changing faces of a set of N coins, with N at least 10^11
(in Donald (1995), I suggest thousands of indicators per neuron, making
N at least 10^14). As a first result, we have that, at any moment, the
Shannon entropy of the distribution of values for these faces is quite
large. Suppose that we want to use such a model as a foundation for the
idea that quantum states are states of knowledge. As long as we assume
that we can identify an observer and his neurons and a set of neural status
indicators and their current status, this seems fairly straightforward.
"The two major problems in the interpretation of quantum
theory can be seen as the "preferred basis problem" -- or the problem of
what quasi-classical entities can exist at a moment; and the problem of
temporal progression -- or of how we go from one quasi-classical moment
to the next. Relativity theory makes defining the notion of a "moment"
a significant part of these problems.
"Indeed, it seems to me that the probabilities in any
physical theory with fundamental indeterministic events have to be lawfully-defined
propensities.
"The fundamental problem which the idea of psycho-physical
parallelism raises for a physicist is whether anything needs to be added
to the mathematical formalism of a physical theory in order to understand
the apparent existence of observers. (...) This seems so implausible to
me that I am prepared to propose as an alternative that there have to be
fundamental physical laws defining the existence of observers (Donald 1999).
"Alternative Physical Theories "At least implicitly, the idea of the observer is central
both to the idea that quantum states are states of knowledge and to the
idea that quantum states are clusters of correlations.
"Including the Observer "As always, however, problems arise when we try to include
the observer in the situation to be described. Now the fact that what we
see depends on what we are enters into the equation. The focus of this
paper has been on the probabilistic prediction of the future development
of the information which defines consciousness given the past history of
that information. The neural unpredictabilities and instabilities discussed
above make even short-term probabilistic predictions of this kind highly
dependent on precisely what form the information takes, regardless of whether
the probabilities in the predictions are ignorance probabilities or propensities.
"Conclusion "The ultimate purpose of theoretical physics is to provide
a consistent and plausible theoretical framework for our individual observations,
including what we learn from others. However, the detailed nature of our
individual observations depend on precisely what parts of the workings
of our brains form the physical aspect of our consciousnesses. In approaches
to the interpretation of quantum mechanics in which the ideas of information
or correlation or mind are fundamental, there are no events except observed
events, and those events and their possible futures are defined by the
solution to this problem of psycho-physical parallelism. However the unpredictability
of the normal functioning of the human brain means that different solutions
at different scales will involve different sets of events with different
future probabilities which cannot be assumed to be better than approximately
consistent. Thus without some solution to the problem of psycho-physical
parallelism such interpretative approaches are incomplete. Nevertheless,
solving the problem is difficult.
"I am grateful to both Chris Fuchs and David Wallace for stimulating walks and challenging conversations."
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