Sun, 26 Jun 1994
To: psyche-d@nki.bitnet
> I would like to hear from people who think that QM is essential for the
> understanding of cognitive processes to explain their position, as I
> believe that when working with systems in the scale of the brain all the
> classical options should be exhausted first.
Many recent postings have been concerned with the question of whether we
are compelled to use quantum mechanical principles in order to understand
1) the physical basis of conscious experience, and 2) the unity of physical
processes in the brain and perhaps even in living processes generally.
The general tendency of these comments has been a) that quantum principles
are probably not related to the basis of cognitive/biological processes, b)
that nonlocal and coherent quantum phenomena cannot occur in the physical
regimes characteristic of biology, and c) that it is methodologically best
to use 'classical' models until we are compelled to 'abandon' them.
In the remarks below I will disagree with each of these three points, in
reverse order. It is precisely my view that the problem should be turned
upside down!
A) In particular, I would like to begin by questioning the disposition to
use so called classical models in preference to quantum mechanical ones...
This is partly a matter of physics, which I will address below with B) but
at the outset let us look at this strange idea: that the best explanations
are in terms of conceptually outdated physical concepts...
Of course, the idea is that there is some scale where these are the basic
concepts, and that brains are among the kinds of things encompassed by that
scale.
In fact, all of physical reality from the layering of atomic levels, and
therefore all chemistry, to the interaction of radiation and matter (e.g.
photosynthesis) to the evolution of Black Holes and the universe at large
is completely and utterly quantum mechanical.
Though it is sometimes said that chemists use classical physics to model
molecular activity, this obscures the essential reality - The reason that
atoms have any structure at all is that electrons follow a basic quantum
mechanical behavior as 'fermions.' For no classical reason at all, it is
the (implicitly nonlocal) nature of fermions that they push each other
out of the way: only one at a time can occupy a given state. No classical
interaction takes place - this is the nature of quantum identity at work.
As a consequence, around the atomic nucleus form vast electronic wings of
possibility, the interlinkages of which is known as the molecular bond...
What attracts us to 'classical' explanations is surely that they seem to
be generalizations of the common sense by which we perceptually navigate.
Yet isn't this fundamentally illusory? The real "rational generalization
of our experience" is quantum mechanics.
To summarize, I know no reason why it is a natural application of Occam's
razor to a priori prefer that explanations at any scale be given in terms
of classical or even local physics. (Perhaps what we see is an image at
the conceptual level of the generative pattern that ontogeny recapitulates
phylogeny: our explanations naturally pass through the birth canal of the
history of physics...) Isn't it even more natural to begin with a quantum
picture?
In a sense, however, I have not begun to deal with what many consider to
be the real physical question: since all of chemistry on up is manifestly
formed out of quantum mechanical structures, the question is not whether
to invoke quantum theory (which we certainly do), but rather whether our
model shall at various levels include certain particular quantum objects:
i.e. spatially extended coherent states.
Which leads on to another question, that of the viability of such states.
B) It is often thought that macroscopic quantum coherence can exist only
at very low temperatures, or in other circumstances which are remote from
biological contexts. Let us inquire into the basis for this view...
Coherence is a matter of phase relationships, which are readily destroyed
by almost any perturbation. For this reason superconducting and superfluid
states of matter exist only in the relative absence of thermal agitation.
However, such states in some sense exhibit only the simplest kind of phase
relationships, and in particular ones coupled to the environment - complex
dynamical systems have many subtle internal phase relationships, and it is
possible to imagine that in some cases the nature of the dynamics protects
these relationships through feedback, amplification, etc.
One way to visualize this is that coherence is actually not the exception,
but the rule: the universe, profoundly quantum mechanical, is coherent up
until proven otherwise - i.e., until constraints destroy the coherence. It
is of course true that a great deal of human life is apparently lived at a
scale where lots of coherence is eliminated by thermal interactions.
Is all the coherence destroyed? Think of a solid door with a lock... We
try to push through the door to no avail. We apply various materials to
the door from various directions: no luck. (This is empirical science!)
Finally we conclude that the door is 'solid,' and that nothing can ever
pass through it: every possible path encounters 'constraints.' Of course,
the key which turns in the lock and opens the door is an exception - it
is the correct 'shape' to pass through the environmental constraints...
The idea with dynamical systems is essentially the same: they might have
relationships with their environments such that they systematically avoid
contact with constraints so that an internal coherent state is maintained.
It is an understatement to say that we have no a priori reason to exclude
the possibility of quantum coherence in biological contexts!
In fact, Frohlich, one of the great pioneers in superstate physics, has
described a model of a system of coupled molecular oscillators in a heat
bath, supplied with energy at a constant rate. When this rate exceeds a
certain threshold then a condensation of the whole system of oscillators
takes place into one giant dipole mode. This is another kind of coherent
structure, in what must be an infinite hierarchy of increasing complexity
and subtlety...
I would also like to comment on references to the tenuous nature of the
nonlocality phenomena which is commonly experimentally studied: i.e. two
particle experiments based on the zero momentum singlet state. Of course,
such 2-particle systems are now studied because they are a case in which
clear predictions can be made - not because they exemplify the limits of
nonlocality. The point is that properties such as momentum are global for
these multiparticle systems: for two particle this leads to a correlation
function which John Bell compared to the "local parameter limit." It turns
out that if there are more particles in the original entangled state then
their quantum correlation is far greater. In fact, David Mermin not long
ago showed that for an n-particle quantum system the correlation function
exceeds the analogue of the Bell local parameter limit by an amount which
grows exponentially with n...
C) So what about life, brains, consciousness, and all that?
I will not argue here that we are compelled by any version of the binding
problem to invoke quantum mechanics in the brain, although I suspect that
such arguments can and will be substantiated, particularly in light of the
significant subtlety of our experience, not to mention interlinkages such
as mutual understanding, empathy, and so forth.
But the thrust of the remarks I am making here is that coherent quantum
phenomena is in fact a natural and ubiquitous aspect of the universe, and
is therefore quite likely found upon turning over many a stone...
Of course, we might expect that living matter in particular is related to
such phenomena because of the integral nature of the evolutionary process,
which would not discard but instead refine or ascend coherent structure.
rhett savage
references
Frohlich, H. (1968) "Long-range Coherence and Energy Storage in Biological
Systems," Int. J. of Quantum Chemistry, v.2, 641-649
Josephson, Brian and Viras, Fotini (1991) "Biological Utilization of Quantum
Nonlocality," Found. Phys. v.21, #2, 197-207
Mermin, N. David (1990) "Extreme Quantum Entanglement in a Superposition of
Macroscopically Distinct States," Phys. Rev. Lett. v.65, #15, 1838-1840
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H is for "h-bar"...
