Structure and function

Date: Tue, 8 Apr 1997 16:54:50 -0700 (PDT)
From: Giuseppe Vitiello <vitiello@vaxsa.csied.unisa.it>
To: quantum-d@teleport.com
Subject: Structure and function

http://xxx.lanl.gov/abs/quant-ph/?9609014

"Structure and function"

 To appear in Proceed. of The Conference "Toward a Science 
 of Consciousness II The 1996 Tucson Discussions and 
 Debates", Tucson (Az)

        Giuseppe Vitiello

        Dipartimento di Fisica
        Universita di Salerno, 84100 Salerno, Italy
        vitiello@vaxsa.csied.unisa.it

abstract

 I discuss the role of quantum dynamics in brain and living matter
 physics. The paper is presented in the form of a letter to Patricia
 S. Churchland.

Dear Patricia, after your talk in Tucson I said to myself: "I must 
meet Patricia Churchland and discuss with her on the role of Quantum 
Mechanics (QM) and quantum formalisms in Consciousness studies". 
However, the Conference was very dense, you very busy and I was "not 
so sure..." from where to start discussing with you. So, at the end 
I decided to write you a letter.

In your talk, which I enjoyed a lot, you were keeping saying "I am 
not so sure...", "I am not so sure...". You explained very well why 
one should have real doubts about "hard" (and easy!) problems (on 
which I will not say anything in this letter) and especially about 
using QM in the study of Consciousness.

From what you were saying I realized that you were completely right: 
"if" QM is what you were referring to, and "if" its use and purpose 
are the ones you were saying, "then" your doubts are really sound 
and, even more, I confirm to you that QM is completely useless in 
Consciousness studies; the popular expression: "a mystery cannot 
solve another mystery" would  be the fitting one.

However, as a physicist I want to tell you that one should not talk 
much "about" QM. Physicists, and other scientists as chemists, 
engineers, etc., "use" QM in a large number of practical applications 
in solid state physics, electronics, chemistry, etc. with extraordinary 
success: it is an undeniable fact that our every day (real!) life 
strongly depends on those successful applications of QM; everything 
is around us (including ourselves!) is made of atoms and the Periodic 
Table of the Elements is clearly understood in terms of QM (recall, 
e.g., the Pauli Principle in building up electronic shells in the 
atoms). QM is not a mystery, from this perspective. The photoelectric 
cell of our elevator or our CD or computer have nothing counter-
intuitive. Of course, I am not saying that the success of QM by itself 
justifies the use of QM in Consciousness studies. I will come back to 
this point later on.

What I want to stress here is that QM is NOT the OBJECT of our 
discussion! There are certainly many open problems in the inter-
pretation of certain aspects of QM which are of great epistemological 
and philosophical interest. However, these problems absolutely do 
not interfere or diminish the great successes of QM in practical 
applications. It is certainly interesting to study these interpretative 
problems, BUT they are NOT the object of our present discussion.

And, please notice that here I am not defending QM, since as I have 
clearly stated many times in my papers, QM does not provide the proper 
mathematical formalism for the study of living matter physics. The 
proper mathematical formalism in such a study turns out to be indeed 
the one of Quantum Field Theory (QFT). But this is a too strong 
statement at this moment of our discussion. Let me go by small steps, 
instead.

I must confess to you that I am not prepared to take as the object of 
our discussion how to approach to the study of Consciousness. As a 
physicist, I would better start by considering some more "material" 
object, as the brain itself or more generally living matter, for 
example the cell. Here I need to explain better myself since the word 
"material" may be misleading.

In Physics it is not enough to search what things are "made of". Listing 
elementary "components" is a crucial step, but it is only one step. We 
want to know not only what things are made of but ALSO "how all of it 
works": we are interested in the Dynamics. In short, fancy words: we 
are interested "in structures AND in functions"; and we physicists are 
attached to our fixations in a so narcissistic way that we even mix up 
structure and function up to the point that we do not anymore make a 
sharp distinction between them. So, to us, having a detailed list of 
components does not mean to know much about the system under study. 
Moreover, it is not even possible to make a "complete" list of com- 
ponents without knowing how they work all together in the system. The 
same concept of component is meaningless outside a "dynamical" knowledge 
of the system. Thus when I say "material" I refer also to dynamical 
laws, not only to the mere collection of components.

After all, what I am saying is quite simple: everybody agrees indeed 
that studying the Tucson phone book does not mean to know the city of 
Tucson. Let me give one more specific physical example: the crystal.

As well known, when some kind of atoms (or molecules) sit in some 
lattice sites we have a crystal. The lattice is a specific geometric 
arrangement with a characteristic length (I am thinking of a very 
simple situation which is enough for what I want to say). A crystal 
may be broken in many ways, say by melting it at high temperature. 
Once the crystal is broken, one is left with the constituent atoms. 
So the atoms may be in the crystal phase or, e.g. after melting, in 
the gaseous phase. We can think of these phases as the functions of 
our structure (the atoms): the crystal function, the gaseous function. 
In the crystal phase one may experimentally study the scattering of, 
say, neutrons on phonons. Phonons are the quanta of the elastic waves 
propagating in the crystal. They are true particles living in the 
crystal. We observe them indeed in the scattering with neutrons. As 
matter of fact, for the complementarity principle, they are the same 
thing as the elastic waves: they propagate over the whole system as 
the elastic waves do (for this reason they are also called collective 
modes). The phonons (or the elastic waves) are in fact the messengers 
exchanged by the atoms and are responsible for holding the atoms in 
their lattice sites. Therefore the list of the crystal components 
includes not only the atoms but also the phonons. Including only the 
atoms our list is not complete! However, when you destroy the crystal 
you do not find the phonons! They disappear! On the other hand, if you 
want to reconstruct your crystal after you have broken it, the atoms 
you were left with are not enough: you must supplement the information 
which tells them to sit in the special lattice you want (cubic or else, 
etc.). You need, in short, to supplement the ordering information which 
was lost when the crystal was destroyed. Exactly such an ordering 
information is "dynamically" realized in the phonon particles. Thus, 
the phonon particle only exists (but really exists!) as long as the 
crystal exists, and vice versa. The function of being crystal is 
identified with the particle structure! As you see there is a lot in 
the quantum theory of matter and please notice: the description of 
crystal in terms of phonons has nothing to do with "interpretative 
problems". It is a well understood, experimentally well tested physical 
description.

Such a situation happens many times in physics; other familiar examples 
are ferromagnets, superconductors, etc.. It is a general feature 
occurring when the symmetry of the dynamics is not the symmetry of the 
states of the system (symmetry is spontaneously broken, technically 
speaking). Let me explain what this means. Consider the crystal as an 
example: the symmetry of the dynamics is the continuous space trans- 
lational symmetry (the atoms may move around occupying any position 
in the available space). In the crystal state however such a symmetry 
is lost (broken) since the atoms must get ordered in the lattice sites; 
they cannot sit, e.g., in between two lattice corners: order is lack 
of symmetry!A general theorem states that when a continuous symmetry 
is spontaneously broken, or equivalently, as we have just seen, an 
ordered pattern is generated, a massless particle is dynamically 
created; this particle (called the Nambu-Goldstone boson) is the 
phonon in the crystal case. Please, notice that this particle is 
massless, which means that it can span the whole system volume without 
inertia, which in turn guaranties that the ordering information is
carried around without losses and that the ordered pattern is a stable 
one since the presence (or, as we say, the condensation) of the 
Goldstone particles of lowest momentum does not add energy to the 
state (it is enough to consider the lowest energy state, namely the 
ground state); in conclusion, the ordered ground state has the same 
energy of the symmetric (unordered) one (we call it normal ground 
state): they are degenerate states. This is why the crystal does exist 
as a stable phase of the matter. Actually, ground states, and therefore 
the phases the system may assume, are classified by their ordering 
degree (the order parameter) which depends on the condensate density 
of Goldstone quanta. We thus see that by tuning the condensate density 
(e.g. by changing the temperature) the system may be driven through 
the phases it can assume. Since the system phases are macroscopically 
characterized (the order parameter is in fact a macroscopic observable), 
we see that a bridge between the microscopic quantum scale and the 
macroscopic scale is established.

All the above is of course possible only if the mathematical formalism 
provides us with many degenerate but physically inequivalent ground 
states which we need to represent the system phases, which in fact have 
different physical properties: this is why we have to use QFT and not 
QM, as I said above. In QM all the possible ground states are physically 
equivalent (the Von Neuman Theorem); QFT is on the contrary much richer, 
it is equipped with infinitely many, physically inequivalent ground 
states and therefore we must use QFT to study systems with many phases.

Above I have been mentioning "theorems": however, I want to stress that 
these mathematical theorems perfectly fit and are fitted by real 
experiments and they represent the only available quantum theory (QFT 
indeed) on which the reliable working of any sort of technological 
gadget around us is based; in spite of the many epistemological and 
philosophical unsolved questions quantum theories may arise.

Now you see why I said that I need to start by considering actual 
material: this is not simply a list of constituents, it is not simply 
specific information from punctual observations, it is not simply a 
lot of real data and statistics, but it is also the dynamics. Otherwise, 
I would only be like one of those extremely patient and skillful swiss 
watch-makers who in the past centuries by mechanically assembling 
together a lot of wheels and levers and hooks were building beautiful 
puppets able to simulate many human movements. But... the phone book 
is not enough and we know that it CANNOT even be complete without the 
dynamics. There is no hope to build up a crystal without the long range 
correlations mediated by the phonons: if you try to fix up atom by atom 
in their lattice sites holding them by hooks you will never get the 
coherent orchestra of vibrating atoms playing the crystal function. 
This is what experiments tell us.

For every new or more refined movement more and more specialized units 
and wheels were needed in building the eighteenth century puppets. And 
certainly the brain, and living matter in general, do present a lot of
very specialized units, which we absolutely need to search for. But our 
list of components will still possibly be incomplete if we do not make 
the effort of thinking of a dynamical scheme, too. There are properties 
of living matter, such as self-ordering, far from the equilibrium 
behaviour, non-dissipative energy transfer on protein molecular chains 
and at the same time dissipativity of biological systems, extremely high 
chemical efficiency and at the same time extremely high number of 
chemical species, and so on, that do point to the existence of a non-
trivial dynamical background out of which the rich phenomenology of 
molecular biology emerges. Like with chemistry before the birth of QM, 
we are challenged to search for a unifying dynamical scheme, which may 
help us in understanding those (collective) properties not in the reach 
of the assembly by "hooks" of the units listed in our phone book.

The problem is not why to expect a quantum dynamical level in living 
matter (and in the brain). In its "inert (or dead!) phase" the matter 
counts among its components atoms, molecules and, as we have seen, other 
units dynamically generated (e.g. the phonon), all of them ruled by 
quantum laws. It would be a really crazy world the one where the same 
atoms, molecules and dynamically generated units would not be ruled by 
the same quantum laws in the "living phase" of matter.

Sometime people gets confused between "classical level" and "quantum 
level". We do speak about "classical limit" of quantum physics, but we 
NEVER mean that, e.g., the Planck constant "becomes" (or "goes" to) zero 
in the classical limit (even when, for sloppiness, we do say that; 
sorry!). The Planck constant has a well definite value which NEVER is 
zero! By "classical" we only mean that certain properties of the system 
are acceptably well described, from the observational point of view, 
"in the approximation" in which certain ratios between the Planck 
constant and some other quantity (of the same physical dimensions) are 
neglected. This does not mean that in such a case one "puts" the Planck 
constant equal to zero, because there are other behaviours, which the 
same system shows simultaneously to the "classical" ones, which only 
can be described by keeping the non-zero value of the Planck constant 
in its full glory. An example: our friend the crystal does certainly 
behaves as a classical object in many respects, out of any possible 
doubt. However, the phonon IS a quantum particle and therefore the 
macroscopic function of being a crystal IS a quantum feature of our 
system; not only, but it is indeed such a quantum behaviour, the one 
of being a crystal, that allows the "classical" behaviour of the 
components atoms as a "whole". Therefore, a diamond is a macroscopic 
quantum system classically behaving when one gives it as a gift to his/
her fiance' (and let's hope they will not argue about the phonon, the 
Schroedinger cat, their love being classical or quantum and all that; 
it would be not at all romantic!).

In the same way, systemic features of living matter, such as ordered 
patterns, sequentially interlocked chemical reactions, non-dissipative 
energy transfer, nonlocal simultaneous response to external stimuli, 
etc., may result as macroscopic quantum features supporting the rich 
phenomenology of molecular biology: the idea, in the QFT approach to 
living matter, is to supplement with a basic dynamics the phenomeno- 
logical random kinematics of biochemistry. 

So the problem is not "if" there exist a quantum dynamics in living 
matter (how it could not exist!), but which are its observable 
manifestations, if any, and in any case how the biochemistry as it 
is emerges from it. Of course, it is more and more urgent the need 
to know all what we can know about the components, their kinematics, 
their engineering; we need working models to solve immediate problems 
(floating boats were used well before knowing Archimede's law); we 
even need patient assembly of cells by hooks to form a tissue, but 
we cannot cry at sky if a cancer develops: from the hook strategy 
point of view only random kinematics and no dynamics is involved in 
tissue formation and as a consequence there is no reason why the same 
list of component cells should behave as a tissue instead of as a 
cancer. Sometime also the eighteenth century puppets were falling down 
in pieces. Therefore, it might be worthwhile to apply what we have 
learned about collective modes holding up atoms in the lattice sites 
(the crystal is a "tissue"!), spontaneous symmetry breakdown, coherence, 
boson condensation, etc., to study, together with biochemists and 
biologists, e.g., the "normal" (or symmetric) state of cancer and the 
ordered state of tissue, as we would say in QFT language.

The task is not at all simple. Living matter is not an inert crystal. 
And we should expect many surprises. For example in the quantum model 
of the brain by Umezawa and Ricciardi the problem of memory capacity 
seems to be solved by seriously considering the dissipative character 
of the brain system. That dissipation enters into play can be naively 
understood by observing that information recording breaks the symmetry 
under time reversal, i.e. it introduces the arrow of time: "NOW you 
know it...!" is the warning to mean that "after" having received some 
information, one cannot anymore behave as "before" receiving it. Thus 
memorizing breaks time reversal symmetry. The brain dynamics is 
therefore intrinsically irreversible. In more familiar words, the brain, 
as other biological systems, has a history. In this respect the brain 
is a clock. Well, to treat dissipative brain dynamics in QFT one has 
to introduce the time-reversed image of the system degrees of freedom. 
One finds thus himself dealing with a system made by the brain and by 
its "mirror in time" image, as a result of the internal consistency of 
the mathematical scheme (if you want to know more about that look at 
my paper in Int.Journal of Mod. Phys. B9 (1995) 973). Problem: are 
consciousness mechanisms macroscopic manifestations of the mirror brain 
dynamics? Does the conscious experience of the flow of time emerges 
from the brain dissipative dynamics? The mirror modes are related to 
brain-environment coupling and at the same time to brain self-
interaction. Does this lead to the conscious sense of "self"?

I realize this is a long letter and I will not talk any longer about 
brain and living matter, consciousness and QFT. I stop here, otherwise 
the Editors of the book on Tucson II will complain for the exceeding 
number of words and I risk to be left out as it was for Tucson I book. 
I hope we can resume our discussion in a future occasion in order to 
be able to join our efforts in the study of the brain.

Arrivederci a presto,   Giuseppe

P.S. I thank you for allowing me to publish this letter. G.