A Quantum Mind - The Penrose-Hameroff model

[Armin]

"Consciousness is a mystery, and the association of consciousness with matter is even more mysterious."

Possibly like other members of this community, I've long been interested in how a particular collection of matter and energy combine to create awareness. While attempts to describe the human brain in relation to computers helped me understand some basic principles of the human brain, it fundamentally lacked in the field I was most interested: awareness, which modern computers clearly do not possess. Though without any other explanation, I felt forced to accept the idea that awareness is just a self-illusion, a product of very complex interactions of neurological systems exclusively within the brain, extending far beyond the capacity of modern computers.

Unknown to myself at the time, the discovery of quantum computing inspired dozens of brain models based upon quantum computational principles. Among them, the most elaborate is the Penrose-Hameroff model.

Gödel's theorem is central to this theory. In 1931, Gödel proved that any theory capable of expressing elementary arithmetic cannot be both consistent and complete. Further to that, for any consistent formal theory that proves certain basic arithmetic truths there is an arithmetical statement that is true, but not provable in theory.

The theorem is not in itself controversial, but what Penrose developed from it is. In his first book on consciousness, The Emperor's New Mind (1989), Penrose argued that the theorem showed that the brain had the ability to go beyond what could be achieved by axioms or formal systems. He argued that this meant that the brain had some additional function that was not based on algorithms (a system of calculations), whereas a computer is driven solely by algorithms. Penrose asserted that the brain could perform functions that no computer could perform. He called this type of processing non-computable.

Penrose went on to consider what it was in the human brain that was not driven by algorithms. Given the algorithm-based nature of most of physics, he decided that the random choice of position etc. that occurs when a quantum wave collapses into a particle was the only possibility for a non-computable process. However, Penrose admitted that the randomness of the wave function collapse, although free from algorithms, is not a basis for any useful form of human understanding.

Penrose now proposed a second form of wave function collapse that could apply where quanta did not interact with the environment, but might collapse on their own accord. He suggests that each quantum superposition has its own piece of spacetime curvature, and when these become separated by more than the Planck length of 10−35 metres, they become unstable and collapse. Penrose called this form of collapse objective reduction.

Penrose suggested that objective reduction represented neither randomness nor the algorithm based processing of most physics, but instead a non-computable influence embedded in the fundamental level of spacetime geometry from which mathematical understanding and, by later extension of the theory, consciousness derived.

This model has its flaws; Penrose states that his ideas on the nature of consciousness are speculative, and his thesis is considered erroneous by experts in the fields of philosophy, computer science, and robotics. Even more criticized was Hameroff's model of how the brain could function in such a quantum arrangement (more info here: http://en.wikipedia.org/wiki/Orch-OR).

Though there is still much debate and research on the subject. According to this same wiki article,

In the last decade, some researchers who are sympathetic to Penrose's ideas have proposed an alternative scheme for quantum processing in microtubules based on the interaction of tubulin tails with microtubule-associated proteins, motor proteins and presynaptic scaffold proteins.

Even though I am skeptical of a quantum mind until further developments in research can prove otherwise, I find the idea very interesting.

I'm curious to hear the thoughts of those here interested in physics, as well as neuroscience (Rule), on the subject of the association of consciousness with matter.

[Sidoh]

I'm not entirely sure why, but I find this super unsatisfying. Awareness is an interesting problem, but I don't think that this is a very good answer.

The superficial reference to Gödel's incompleteness theorems is a little unsettling. It's really quite a complicated thing, and they seem to be abusing it a little here. This is pretty pedantic, but the first thing they mention is the second theorem, which is a corollary to the first theorem, referenced in the last sentence of the first paragraph. They seem to suggest it's the other way around (by use of language like 'Further to that, ...")

I don't really buy the most significant jump made in the theory: that the truth of Gödel's theorems suggests that the brain can follow some non-computable process. Gödel's theorems argue that for any set of sufficiently powerful axioms capable of arithmetical operations, then one of the following is true:
- Some axioms are in contradiction with others
- There are facts about the natural numbers (1, 2, 3, ...) that are true, but not provable using the axioms

In some way, this limits what we can know. I don't really think anything I'm aware of suggests that the human brain is capable of knowing more than we could if we were restricted to axiomatical systems. Indeed, I think the few things that we actually can know (in an epistemological sense) are through the use of axiomatical systems.

I suppose I'd have to read the book before I pass judgement, but it seems like some pretty weak theorizing to me.

[MyndFyre]

This is pretty pedantic,

And shallow.

[while1]

This is pretty pedantic,

And shallow.

I agree, shallow and pedantic.