Quantum mind

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The quantum mind program is founded on the premise that quantum theory is necessary to understand the mind and brain.

This is very much a minority opinion, although it does have the support of the well-known mathematical physicist Roger Penrose. Other proponents include Stuart Hameroff, Subhash Kak, Karl Pribram, Henry Stapp, Brian Flanagan and Michael Lockwood. (See references below.)

A common argument underlying the quantum mind thesis is that classical mechanics cannot explain consciousness, if only because Galileo and Newton (together with their admirers, viz., Locke, Hobbes and Descartes) excluded the secondary qualities from the physical world.

The main argument against the quantum mind is that the brain is warm, wet and noisy and that the structures of the brain are much too large for quantum mechanics to be important. Consequently, it is difficult for coherent quantum states to form for very long in the brain, and impossible for them to exist at scales on the order of the size of neurons. These issues have led Penrose to argue that consciousness is not a consequence of interactions between neurons in the brain but arises as from microtubules within cells, which are much smaller and for which quantum effects could be significant. This was originally the theory of Stuart Hameroff.

On the other hand, a system does not cease to be quantum because it is wet and noisy. And then, what was previously dismissed as "noise" in the brain has recently been discovered to be complex signals. Then, too, lasers, transistors and black holes are all arguably "large," and yet exhibit quantum behavior.

Then again, if the brain is fractal in character, it may well exhibit sensitive dependence on initial (quantum) conditions. Given the fractal character of dendritic arborizations, brain function may depend on self-similar processes at lower spatio-temporal scales. Or, "neural form follows quantum function." On this view, it seems to make a kind of sense that the matrix mechanics used to model neural nets recapitulates the matrix mechanics of quantum mechanics, as formulated by Heisenberg.

This view is very different from conventional views of how the brain works, in which neurons communicate via electric impulses which trigger the release of neurotransmitters in the synapses. In the conventional view of brain function, microtubules play no significant role in brain function other than to provide structural support to the neurons. The quantum mind thesis has been criticized on a number of grounds. For one, it fails to explain how chemicals and physical processes which affect neuron functioning would cause generally predictable changes in consciousness, whereas the conventional theory provides an explanation for how psychoactive substances work and how the brain would react to injury.

On the other hand, many of these critics fail to understand that electrical impulses are quantum in nature, as with everything else in the material universe. If all matter consists of quantum fields, as Dyson makes explicit in his Scientific American article on "Field Theory," then the brain just is a collection of such fields. (See reference below.)

Lockwood, Stapp, and Flanagan have argued that the rich state space of quantum theory easily accommodates the variety of perceptual state spaces, whereas classical theory cannot.

Also, although decoherence mechanisms such as emission of thermal radiation appear to apply to large molecules such as microtubule protein subunits and synaptic vesicle proteins, making quantum coherence on the scale proposed for quantum mind theories unlikely, more recent work has turned up surprising and even counter-intuitive relations between quantum noise and quantum information processing. (See the article by Bennett, Shor et al., referenced below.)

The link with biophotons is discussed in [1].

Quantum theories of mind are among the few classes of theories acceptable in the philosophical stances of pseudonomenalism and mind/brain identity theory.

There is another type of quantum theory of mind called the many-minds interpretation that is invoked as a conservative version of the many-worlds interpretation of quantum theory and does not involve collapse of the QM wave function. Of course, this alternative only appears conservative once one chooses to ignore the rather glaring fact that Occam has thus been thrown out the door, given that "many worlds" multiplies entities ad infinitum.

More recently, Hartle, 't Hooft, Smolin and Peres have awakened the largely dormant "hidden variables" interpretation of quantum theory, which would also obviate the need for quantum-mechanical collapse as typically "understood."

[edit] See also

Biophoton
Consciousness
David Bohm
Electromagnetic theories of consciousness
Evolutionary neuroscience
Holonomic brain theory
Many-minds interpretation
Quantum brain dynamics
Quantum indeterminacy
Sensory Integration Dysfunction
Space-time theories of consciousness
Spin-Mediated Consciousness Theory
Theory of mind
Uncollapsing theorem

[edit] Useful references

Wikibooks Consciousness studies has more about this subject:

Bennett, Charles H., Shor, Peter W., Smolin, John A. and Thapliyal, Ashish V. "Entanglement-Assisted Classical Capacity of Noisy Quantum Channels," Phys. Rev. Lett. 83, 3081–3084 (1999). (http://prola.aps.org/abstract/PRL/v83/i15/p3081_1)
Bohm, David. Quantum Theory. Englewood Cliffs, NJ: Prentice-Hall, Inc., 1951. see David Bohm for more of his relevant references.
Dyson, Freeman. "Field Theory," Scientific American, 188, No. 4, April 1953, pp. 57-64.
Flanagan, Brian. "Are Perceptual Fields Quantum Fields?" http://wordassociation1.net/FieldWork.html
Hodgson, David. The Mind Matters. Oxford University Press, 1993.
Lockwood, Michael. Mind, Brain and the Quantum. Cambridge, MA: Basil Blackwell Ltd., 1989.
Schrodinger, Erwin. Mind and Matter. Cambridge University Press, 1959.
Weyl, Hermann. Mind and Nature, University of Pennsylvania Press, 1934.
Wigner, Eugene. "Physics and the Explanation of Life," in Foundations of Physics, vol. 1, 1970, pp. 34-45.
Wikibook on consciousness