Quantum Approaches to Consciousness
Stanford Encyclopedia of Philosophy
Atmanspacher starts his article by stressing that the randomness inherent in quantum theory is in sharp contrast to the determinism that permeates classical physics. This randomness is a fundamental characteristic of the theory, not a result of ignorance of the full system, as is the case in statistical mechanics.
Atmanspacher is also careful to draw a clear distinction between correlation and cause and effect. When two effects are correlated, one effect may cause the other, but equally well it may not, with the correlation being due to third cause lying in the common history of the two effects. He points out that while causation explains why something happens, correlation does not of itself explain why either of the correlated effects happen. Thus the fact that certain brain areas or functions are activated during consciousness does not necessarily explain what causes consciousness.
Atmanspacher discusses the ideas of the physicist, Henry Stapp. Stapp’s ideas on quantum theory are quite close to the Copenhagen interpretation, with major importance attached to the distinction between the observer and the observed. Stapp places the divide between observer and observed in the brain, and thinks that consciousness can influence brain activity.
The article gives some prominence to Beck and Eccles. They have done detailed work on possible quantum level information transfer at the synapses, involving electron transfer between biomolecules, but they have not provided a link from this to consciousness.
Atmanspacher appears relatively sympathetic to the Penrose/Hameroff model, which is unusual in consciousness studies. He comments that Hameroff’s microtubule theory is the lowest physical level at which a quantum consciousness theory has been attempted, with other theories implemented somewhere between synaptic and neuronal assembly level.
The article explains that the Penrose’s thinking derives from the Gödel theorem, and his interpretation of the theorem, which is that there is some non-computable function in the human brain. This latter is realised by a gravitationally based reduction of the wave function. Atmanspracher points out that in contrast to other quantum theories of consciousness, such as Stapp, Penrose is proposing an alteration to the presently agreed quantum theory. Hameroff has provided the physical position in the brain for the implementation of this theory. He suggests that the microtubules within the neurons might be a suitable location, because they might be screened from the environment to support quantum coherence for a sufficient period of time.
Atmanspracher, who is much more open minded than most commentators on consciousness does, nevertheless, fall into the old habit of quoting the critics of the model without quoting Hameroff’s response. Thus he mentions Tegmark’s objections to the theory based on the speed of decoherence, but not Hameroff’s criticism of Tegmark’s calculations. Similarly, the article refers to a paper by Grush and Churchland as providing an objection on philosophical grounds, but it does not explain either their objections, not mention the reply to them by Penrose and Hameroff. The last part of the section on Penrose/Hameroff also states that there are no plans for empirical confirmation of the theory, whereas Hameroff has proposed 20 possible tests, including plans to test Penrose’s theory of a gravitationally driven wave function collapse.