Quantum Mechanics and Consciousness

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Mechanist (December 09, 2008, 18:32:26 PM):
Can quantum mechanics and consciousness be linked?

Quantum physics and Consciousness. Are they connected? The microtubule connection.

Research into the brain-body-mind problem is ongoing and one way of attempting to understand it is to try and describe consciousness in terms of material particles and fields interacting between inputs, internal states, and outputs without any intrinsic meaning. Terms such as “feeling”, “intention”, “knowing” and “choice” are thus not viewed as primary causal factors of consciousness, but a byproduct of these blind interactions.

Quantum physics has not been at the forefront to attempt to describe consciousness as the neurocomputational model of laterally connected input layers of the brain’s neurocomputational architecture is viewed as the most credible explanation for consciousness. One problem that quantum mechanics face is the effect of quantum decoherence (The Role of Decoherence in Quantum Mechanics) and failures to measure it. Essentially, quantum states are believed to be too sensitive and fragile to disruption by thermal energy to affect the macroscopic nature of proteins and other macromolecular structures.

The Penrose-Hameroff orchestrated objective reduction (orch. OR) model provides a basis to connect consciousness with quantum mechanics. Microtubules are integral in this theory.

Connecting quantum mechanics, aromatic ring pi-bonds, protein formation, microtubules and consciousness.

The “quantum physics” and “aromatic ring pi bond” connection.
An aromatic (aromaticity) compound is composed of a conjugated planar ring system with delocalized pi electron clouds. Benzene is an example of an aromatic compound (Figure 1). In benzene (and other aromatic compounds) the double bonds are shorter than the single bonds, causing the carbon atoms to be pulled and pushed between two states and thus vibrate between two states (Figure 2). The pi electrons are also delocalized above and below the carbon ring (Figure 1). Aromatic compounds are thus described to be resonating and are best described quantum mechanically.

The “aromatic ring pi bond” and “protein formation” connection.
4 amino acids contain aromatic rings: tyrosine, phenylalanine, tryptophan and histidine (Figure 3). Histidine, however has 6 delocalized electrons but not a benzene ring and is hydrophilic (more polar).

When peptide chains fold to form proteins, the structure is stabilized and dynamically regulated in the intracellular aqueous phase. Polar side groups face outwardly and react with the polar aqueous milieu, while non-polar regions face inwardly (Protein folding). Aromatic amino acids are more non-polar and thus coalesce more readily in the centre of a protein. When aromatic amino acids coalesce it allows London force van der Waals interactions between the non-polar electron clouds of the aromatic rings, causing quantum resonation of the coalesced non-polar aromatic rings (Figure 4).

Mechanist (December 09, 2008, 18:34:59 PM):

The “protein formation” and “microtubule” connection.
Microtubules are long, hollow, cylindrical, filamentous, tube-shaped protein polymers consisting of alpha and beta tubulin dimers and form part of the cytoskeleton (Figure 5, Figure 6, Figure 7). Microtubules play important roles in cell signaling, cell division and mitosis, vesicle and mitochondrial transport and play crucial roles in the development and maintenance of cells and cell shape. Microtubules are highly dynamic cytoskeletal fibres and are capable of two types of dynamics:
1) Treadmilling and
2) Dynamic instability
Microtubules polymerize (rescue/elongate) at the positive (+) end and depolymerize (catastrophe/shorten) at the negative (-) end. During treadmilling, polymerization and depolymerization occur at equal rates and thus the microtubules do not change in length but changes position 4-dimensionally.
During dynamic instability, either the (+) end polymerizes quicker than the (-) end can depolymerize resulting in total elongation of the microtubule, or the (-) end depolmerizes quicker than the (+) end can polymerize resulting in total shortening of the microtubule. In the Inner Life of the Cell video this behavior can be witnessed at time approx 1.07-1.11min (rescue) and 1.11-1-15 (catastrophe).

Figure 8 shows the structure of the alpha- and beta-tubulin dimers and the prevalence of aromatic amino acids (1sa0.pdb). At a higher resolution (Figure 9) it is clear that the aromatic amino acids are close enough to each other (< 2nM) to allow for London van der Waals (Figure 10) interactions. When tubulins polymerize during dynamic instability (rescue) they form tube-like structures (Figure 7). Quantum level resonance as a result of quantum level dipole oscillations (London van der Waals forces) within hydrophobic pockets result in functional protein vibrations which depend on quantum effects (Figure 11). The quantum effect on a single tubulin protein conformation is superposed and exists in both states simultaneously and acts as a qubit (as in quantum computer). Thus, the elegant formation of microtubules (Figure 7 and Figure 12) can in theory constitute a quantum computer (more detail).

The “microtubule” and “consciousness” connection.
Microtubules extend throughout dendrites and axons (neural cells) and play crucial roles in controlling synaptic strengths responsible for learning and cognitive functions through mechanical signaling, communication as well as cytoskeletal scaffolding (cell movement).

In a nutshell, the Penrose-Hameroff orch OR model proposes that quantum effects are relayed through pi-bonds in hydrophobic pockets within microtubules to the macroscopic structure of the brain, resulting in consciousness. Microtubules are thus viewed as protein quantum computers.

Off course the detail of this model is much more in depth and the following documents and web pages illustrates it beautifully. Enjoy!!!

1) Quantum consciousness
2) The Brain Is Both Neurocomputer and Quantum Computer
3) That's life! The geometry of pi electron resonance clouds.
4) Quantum computation in brain microtubules? The Penrose-Hameroff "Orch OR" model of consciousness
5) Microtubules - Nature's Quantum Computers?
Mefiante (December 10, 2008, 10:44:06 AM):
Hello, and welcome to the forum, Mechanist.

There are several grave problems with and gaps in Roger Penrose’s ideas concerning consciousness.

Basically, he posits that wave function collapse, i.e. the generation in a quantum system of one definite state from a superposition of all possible ones (potentially infinite in number) as contained in the system’s wave function, is precipitated by a quantum gravity effect that exceeds a certain threshold, which somehow then accounts for consciousness but it is unclear how.

There are three major problems with the model. Firstly, the question of how wave function collapse is triggered and how it proceeds physically is shrouded in mystery. We have yet to construct a valid model for it, let alone a scientific theory thereof. The proposed consciousness model is critically dependent on this component and since our knowledge about it is very limited, the proposed consciousness model remains questionable.

Secondly, after many decades of concerted effort, we still haven’t succeeded in tying Quantum Mechanics and General Relativity together into a coherent unified field theory. Thus, Penrose’s proposal of a quantum gravitational effect above a certain threshold is itself at this stage pure conjecture, as is its supposed ability to bring about (spontaneous) wave function collapse. Added to our abovementioned lack of knowledge about the wave function collapse process itself, it becomes clear that we have severely limited theoretical grounds for accepting the model as credible. Moreover, since we are tapping in the dark about wave function collapse, it is hard to see how the model could be tested empirically, even in principle.

Thirdly, we have no adequate model of consciousness mostly because we have no clear idea of what it might be physically. So once again the link between quantum effects and consciousness is at best tenuous.

In summary, the Penrose/Hameroff model is highly speculative and contentious, it has many problems that detract from its plausibility, and very few quantum physicists find it convincing. That doesn’t mean that it is false (Penrose is after all a well-respected mathematician who has collaborated with Stephen Hawking, no less), only that it would be premature to accept it before the problems and gaps have been properly addressed.

Mechanist (December 10, 2008, 12:07:25 PM):
Hi Anacoluthon64,

Thank you for your comments. I agree there are problems with the model, however, whether they are grave I would argue remains to be tested.

1) From what I understand, Penrose posits that the wave function is fundamentally unstable and spontaneously collapses due to an objective (intrinsic) feature of space-time reality/geometry. The model depends on this feature, whether it is testable or even verifiable is in question (like you said). If it is a grave problem for this model remains to be seen.

2) Do you think Loop quantum gravity and the attempt at a Hamiltonian formulation of general relativity has potential, or is String theory more plausible. My knowledge is limited with regards to the mathematical aspect, but I am willing to learn.

3) While there is no model for consciousness, materialistic explanations do seem to have grave problems. Some are of the opinion that consciousness is a fatal problem for materialism. This paper argues at length the strengths and weaknesses of materialistic explanations. Type-F monism and type-D dualism are compatible with the Penrose-Hamerhoff model.

The Penrose-Hamerhoff model does have some serious problems, I don't think it should be discarded though. Evidence of quantum computation through quantum coherence in photosynthetic systems have been described.

For example:
Nature;Vol 446;12 April 2007: Quantum path to photosynthesis
Elsewhere in this issue, Engel et al. (page 782) take a close look at how nature, in the form of the green sulphur bacterium Chlorobium tepidum, manages to transfer and trap light’s energy so effectively. The key might be a clever quantum computation built into the photosynthetic algorithm.

The process is analogous to Grover’s algorithm in quantum computing, which has been proved to provide the fastest possible search of an unsorted information database.

And in this article: Nature;Vol 446;12 April 2007: Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems.
When viewed in this way, the system is essentially performing a single quantum computation, sensing many states simultaneously and selecting the correct answer, as indicated by the efficiency of the energy transfer.

Quantum theory as it stands is incomplete with regards to the collapse of isolated quantum superpositions. Whether the solution is compatible with this model remains to be seen I guess.
Mechanist (December 10, 2008, 14:46:16 PM):
Six questions regarding the model:
(1) Explain why no one else has as yet succeeded in constructing a viable quantum gravity/GR formulation.
Because it is a fundamental problem in contemporary physics today. Whether the solution is compatible with the model remains to be seen.

(2) Give the field equations for your quantum gravity formulation and the assumptions that led to that particular gauge field.
I can't, and doubt anyone can at present.

(3) Show how those field equations contain something that will, through application of an appropriate operator, produce effects that can reasonably be thought of as consciousness – in other words, give a physical account of the observables in your system and how they or a subset thereof can be construed as consciousness.
No one exactly knows what consciousness is or how to describe it. Field equations to describe consciousness at present do not exist.

(4) Explain why no one else properly understands either what wavefunction collapse actually is or what the physics are behind its production, and give a physical interpretation of how it is actually produced by the application of the aforesaid (Hermitian) operator(s).
The reason why no-one properly understand what wave function collapse is, is because it is still a fundamental problem in quantum physics.

(5) Give a sufficiently complete mathematical model of consciousness and show how the model coheres with your field equations and the necessary operator(s) that produce conscious states.
Consciousness needs to be understood (and clearly defined), and in order for it to be understood in the Penrose-Hamerhoff model, an understanding of the collapse of the wave-function is needed.

(6) Explain why no one else knows what consciousness actually is and why the Penrose-Hameroff orch OR model is any different from a model that goes in essence, “abracadabra, come forth ye quanta! Hey presto, consciousness!”
Is there any model at present that doesn't need an "abracadabra", and is a plausible model for consciousness? Consciousness is an open question, and no clear, coherent explanation for it exists at present.

The Penrose-Hamerhoff model is just another model.


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