Quantum chaos in the rat ventral tegmentum?

Matthew Donald wrote:
> If they could be built, large-scale quantum computers
> would be able to perform (some) large calculations much
more quickly and efficiently than any classical computer.
But quantum computers are difficult to build at any scale,
and therefore small-scale quantum computers (however
impressive they may be) are not useful.  As I said, "A
little quantum computation is just a very expensive
ordinary computation."  This makes me doubt that biological
systems could evolve useful quantum computation.

bj:
Thanks to Donald for his thoughtful remarks. I should like
to make three related points by way of reply: (1) Q
computation research is very new, and may well continue to
reveal all sorts of remarkable features of the quantum
realm; (2) that realm is only incompletely understood;
Planck proposed energy quanta in 1900 & thirty years later,
quantum mechanics was regarded as completed. Gell-Mann has
recently observed that what happened was that the
architects of Copenhagen "brainwashed" a generation of
physicists into believing as much. (3) Biological systems,
from a physical standpoint, just are large quantum fields;
ergo all their processes are inherently quantum, including
those processes regarded as computational. It is helpful to
recall Umezawa's words in this connection:

"Among the many biological objects a particularly
interesting one is the brain. For any theory to be able to
claim itself as a brain theory, it should be able to
explain the origin of such fascinating properties as the
mechanism for creation and recollection of memories and
consciousness.

For many years it was believed that brain function is
controlled solely by the classical neuron system which
provides the pathway for neural impulses. This is
frequently called the neuron doctrine. [...]

There have been many models based on quantum theories, but
many of them are rather philosophically oriented. The
article by Burns . . . provides a detailed list of papers
on the subject of consciousness, including quantum models.
The incorrect perception that the quantum system has only
microscopic manifestations considerably confused this
subject. As we have seen in preceding sections,
manifestation of ordered states is of quantum origin. When
we recall that almost all of the macroscopic ordered states
are the result of quantum field theory, it seems natural to
assume that macroscopic ordered states in biological
systems are also created by a similar mechanism."

Umezawa, 'Advanced Field Theory'


A few more instructive remarks come to mind:

"There is nothing else except these fields: the whole of
the material universe is built of them."

Dyson, "Field Theory," Scientific American, 188, No. 4,
April 1953


"all chemical binding is electromagnetic in origin, and so
are all phenomena of nerve impulses."

Salam, 'Unification of Fundamental Forces'


"The text of this volume claims that the mathematical
formulations that have been developed for quantum mechanics
and quantum field theory can go a long way toward
describing neural processes due to the functional
organization of the cerebral cortex."

Pribram, 'Brain and Perception'


"Since matter clearly influences the content of our
consciousness, it is natural to assume that the opposite
influence also exists, thus demanding the modification of
the presently accepted laws of nature which disregard this
influence."

Wigner, "Physics and the Explanation of Life," in
Foundations of Physics, vol. 1, 1970


> I wrote
> > quantum computers need very precisely-defined quantum
> > states.  Only systems which can be very precisely tuned
> can
> > use such states in the required way.  But evolution
> does not
> > tune something unless it is already producing some sort
> of biological benefit.

bj:
In the way that our retinal neurons are tuned to respond to
photons in the visible spectrum, perhaps, or in the way our
heat sensors are tuned to IR photons.


> Pereira replied
> > Artificial quantum computers need very precise
(although not absolutely precise, given what Heisemberg
taught us) states because the measurement is made by an
external observer. In a biological quantum computer, the
measurement would be made by the computer himself,
therefore some kind of fuzzy logic may be possible.

bj:
At a minimum, Heisenberg needs to be taken with a large
grain of salt. See Wick's fine introduction to these issues
in his 'Infamous Boundary.' For more scholarly accounts,
Holland's 'Quantum Theory of Motion' and Jammer's seminal
'Philosophy of QM' are rcommended.


> Heisenberg taught us that measurements of the position
> and momentum of a single particle could not both be
> completely precise.

bj:
This is only one interpretation of what the uncertainty
relations tell us, and it may well be incorrect. (See Wick,
e.g.)


> I am talking about a different kind of precision here;
> about the precision required in the quantum wavefunctions
used within a quantum computer.  These states can be
exactly specified and need to be to use algorithm's like
Shor's.  Biological systems however do not, in general,
control at this level.  Biochemistry involves ions and
atoms and molecules bumping into each other. It is heat
which keeps life moving. Heat is the enemy in quantum
computation.

bj:
Again, "quantum computation" as usually "understood." On
the field level, the exchange of photons in the IR region
is not essentially different from photon exchanges at other
frequencies.

There was an article in SciAm some years ago which posited
a mechanism whereby birds employ a mechanism for damping
quantum noise in their auditory processes. I would hazard a
simple prediction to the effect that other such mechanisms
remain to be found throughout the animal kingdom. (They may
already have been found -- I haven't checked.)

For the interested, I have explored these issues at greater
length here:

http://wordassociation1.net/FieldWork.html