Wouldn’t you like to know what’s going on in my mind?

I suppose most theoretical physicists who (like me) are comfortably past the age of 60 worry about their susceptibility to “crazy-old-guy syndrome.” (Sorry for the sexism, but all the victims of this malady I know are guys.) It can be sad when a formerly great scientist falls far out of the mainstream and seems to be spouting nonsense.

Matthew Fisher is only 55, but reluctance to be seen as a crazy old guy might partially explain why he has kept pretty quiet about his passionate pursuit of neuroscience over the past three years. That changed two months ago when he posted a paper on the arXiv about Quantum Cognition.

Neuroscience has a very seductive pull, because it is at once very accessible and very inaccessible. While a theoretical physicist might think and write about a brane even without having or seeing a brane, everybody’s got a brain (some scarecrows excepted). On the other hand, while it’s not too hard to write down and study the equations that describe a brane, it is not at all easy to write down the equations for a brain, let alone solve them. The brain is fascinating because we know so little about it. And … how can anyone with a healthy appreciation for Gödel’s Theorem not be intrigued by the very idea of a brain that thinks about itself?

(Almost) everybody's got a brain.

(Almost) everybody’s got a brain.

The idea that quantum effects could have an important role in brain function is not new, but is routinely dismissed as wildly implausible. Matthew Fisher begs to differ. And those who read his paper (as I hope many will) are bound to conclude: This old guy’s not so crazy. He may be onto something. At least he’s raising some very interesting questions.

My appreciation for Matthew and his paper was heightened further this Wednesday, when Matthew stopped by Caltech for a lunch-time seminar and one of my interminable dinner-time group meetings. I don’t know whether my brain is performing quantum information processing (and neither does Matthew), but just the thought that it might be is lighting me up like a zebrafish.

Following Matthew, let’s take a deep breath and ask ourselves: What would need to be true for quantum information processing to be important in the brain? Presumably we would need ways to (1) store quantum information for a long time, (2) transport quantum information, (3) create entanglement, and (4) have entanglement influence the firing of neurons. After a three-year quest, Matthew has interesting things to say about all of these issues. For details, you should read the paper.

Matthew argues that the only plausible repositories for quantum information in the brain are the Phosphorus-31 nuclear spins in phosphate ions. Because these nuclei are spin-1/2, they have no electric quadrupole moments and hence corresponding long coherence times — of order a second. That may not be long enough, but phosphate ions can be bound with calcium ions into objects called Posner clusters, each containing six P-31 nuclei. The phosphorus nuclei in Posner clusters might have coherence times greatly enhanced by motional narrowing, perhaps as long as weeks or even longer.

Where energy is being consumed in a cell, ATP sometimes releases diphosphate ions (what biochemists call pyrophosphate), which are later broken into two separate phosphate ions, each with a single P-31 qubit. Matthew argues that the breakup of the diphosphate, catalyzed by a suitable enzyme, will occur at an enhanced rate when these two P-31 qubits are in a spin singlet rather than a spin triplet. The reason is that the enzyme has to grab ahold of the diphosphate molecule and stop its rotation in order to break it apart, which is much easier when the molecule has even rather than odd orbital angular momentum; therefore due to Fermi statistics the spin state of the P-31 nuclei must be antisymmetric. Thus wherever ATP is consumed there is a plentiful source of entangled qubit pairs.

If the phosphate molecules remain unbound, this entanglement will decay in about a second, but it is a different story if the phosphate ions group together quickly enough into Posner clusters, allowing the entanglement to survive for a much longer time. If the two members of an entangled qubit pair are snatched up by different Posner clusters, the clusters may then be transported into different cells, distributing the entanglement over relatively long distances.

(a) Two entangled Posner clusters. Each dot is a P-31 nuclear spin, and each dashed line represents a singlet pair. (b) Many entangled Posner clusters. [From the paper]

(a) Two entangled Posner clusters. Each dot is a P-31 nuclear spin, and each dashed line represents a singlet pair. (b) Many entangled Posner clusters. [From Fisher 2015]

What causes a neuron to fire is a complicated story that I won’t attempt to wade into. Suffice it to say that part of the story may involve the chemical binding of a pair of Posner clusters which then melt if the environment is sufficiently acidic, releasing calcium ions and phosphate ions which enhance the firing. The melting rate depends on the spin state of the six P-31 nuclei within the cluster, so that entanglement between clusters in different cells may induce nonlocal correlations among different neurons, which could be quite complex if entanglement is widely distributed.

This scenario raises more questions than it answers, but these are definitely scientific questions inviting further investigation and experimental exploration. One thing that is far from clear at this stage is whether such quantum correlations among neurons (if they exist at all) would be easy to simulate with a classical computer. Even if that turns out to be so, these potential quantum effects involving many neurons could be fabulously interesting. IQIM’s mission is to reach for transformative quantum science, particularly approaches that take advantage of synergies between different fields of study. This topic certainly qualifies.* It’s going to be great fun to see where it leads.

If you are a young and ambitious scientist, you may be contemplating the dilemma: Should I pursue quantum physics or neuroscience? Maybe, just maybe, the right answer is: Both.

*Matthew is the only member of the IQIM faculty who is not a Caltech professor, though he once was.

60 thoughts on “Wouldn’t you like to know what’s going on in my mind?

  1. What, no mention of Orchestrated OR or quantum biology? We now know there are room temperature quantum processes occurring in the microtubules in the neurons of the brain (as well as in photosynthesis and bird navigation). Sir Robert Penrose and Stuart Hameroff developed their Orchestrated OR (Objective Reduction) theory about it 20 years ago and now it’s being buttressed by new findings in quantum biology. Not so crazy, after all.

      • We still have them (!), and they include nuclear spins in microtubules (and geometric qubits similar to Preskill-like topological quantum error correction). Evidence shows quantum resonances in microtubules, and that anesthetics act on microtubules to erase consciousness. Fisher’s nuclear spin is proposed to occur in axon terminals (similar to where Beck and Eccles invoked quantum effects years ago – apparently unbeknownst to Fisher) but all evidence suggests consciousness occurs in post-synaptic dendrites/soma. Microtubules are (quantum) computational devices whereas Fisher’s proposal lacks any processing capabilities nor memory. See:
        Hameroff S, Penrose R (2014) Consciousness in the Universe – A Review of the Orch OR Theory Physics of Life Reviews 11(1):39-78

        Please explain why Fisher’s arguments are more persuasive than ours.

        Stuart Hameroff

        • Matthew comes at the subject with the attitude of a hard-nosed condensed matter physicist. I like the angle of systematically searching for a possible mechanism, settling on P-31 nuclei, realizing that the existence of something like Posner clusters would be needed, and then finding out that such objects really do exist.

          Though I did not mention it in my post, I am also very intrigued by another point mentioned in the paper — that Li-6 has very different effects on rat behavior than Li-7.

          I also like that Fisher is proposing a concrete experimental program (including studies confirming those Lithium results). He’d like to better characterize concentration of Posner clusters, use liquid state NMR to measure spin lifetimes in such clusters, measure Posner cluster melting rates, and study transmembrane phosphate transport, among other things.

          Truth be told, I have not studied your scientific papers, so should not have made any comment. I know your work only through popular accounts by Penrose and others. Nor am I well informed about neuroscience in general. I did not intend to denigrate your ideas, only to encourage people to read Fisher’s paper.

          • We’re hard-nosed also. We don’t accept the AI/Singularity/ reductionist accounts of the brain as neuronal computer which are wrong for many reasons. We published 20 testable predictions of Orch OR in 1998 and reviewed them in our 2014 paper. 6 are confirmed and the other 14 undecided.

            We not only propose experimental approaches, experiments have already validated many aspects of Orch OR. I don’t think Fisher has a clue about the brain,
            and, with all due respect, neither do you. You could at least read our paper and decide for yourself instead of dissing it. I would like to hear your opinion.

            Why don’t you come to our conference ‘The Science of Consciousness’
            next April. See http://www.consciousness.arizona.edu
            Among many other things, there will be a workshop and Plenary session on Quantum AI with a talk by Hartmut Neven from Google’s Quantum AI group.
            He was into quantum annealing, as you are. There will also be sessions on quantum biology.

            • I definitely agree with the statement that I have no clue about the brain!

              To me a natural place to start thinking about these issues is to ask about physical mechanisms for long coherence times, as Fisher does. From your 2014 review I learned about the work of Bandyopadhyay et al., which seems intriguing. Matthew is approaching the subject from a complementary viewpoint, which also leads to experimentally testable hypotheses. We’ll see where it goes from here.

            • Thanks John

              Complementary among various quantum biological processes is possible. Indeed there is quantum coherence all over biology, in DNA, membranes and proteins, all in pi resonance clouds in non-polar ‘quantum channels’ or ‘quantum underground’ as we call it. Its the intra-moelcular region of ‘olive oil-like’ solubility where anesthetic gases act to specifically erase consciousness. The pi resonance dipoles (electric and magnetic) can couple to nuclear spin and states.

              There’s also quantum spin separation in bird brain navigation, and perhaps olfaction. So maybe Posner complexes also. But these are limited.
              Fisher says in his article Posner molecules are the only possible neural qubit.
              Microtubules are everywhere, and running he show inside cells. He’s wrong and uninformed.

              Pardon me if I have a chip on my soldier but we’ve been ridiculed for 20 years for suggesting what people are now taking for granted and still ignoring us. You said Fisher’s model was more persuasive than ours. Is it? Why?

              Here are two of our recent papers (physicists Travis Craddock, Jack Tuszsynski and I) about quantum states in microtubules,


              (i they want money email me and I’ll send a copy)

              Here are two other papers showing effects in other systems very similar to what we propose in microtubules



              This one is about microtubules governing DNA repair by dynamic dancing. It
              may not be quantum entanglement but is interesting

              Long coherence times…Many studies suggest quantum coherence times are extended in biomolecules by coupling to mechanical vibrations in the molecule (as first suggested by Frohlic in the 1960s/1970s, and proven in the AIP paper above. This is especially favorable in microtubules which have mechanical resonances due to their Fibonacci lattice geometry. In fact Bandyopadhyay has recorded (using STM probes) vibrational resonances from microtubules inside neurons in gigahertz, megahertz and kilohertz, and converted them to sound so you can hear these vibrations.


  2. Dr. Fisher and me share another passion, its Golf. Ever time we are in Santa Barbara Matthew and me play. it gives us a brake from life, just for a while. After all, he is my son-in-law!!!

  3. Einstein wrote that “When the solution is simple, God is answering.”

    Where is the simplicity underlying the storied complexity of the mind & brain?

    Helmholtz noted that “Similar light produces, under like conditions, a like sensation of color.”

    We can both broaden and tighten this observation and, with a nod to Heisenberg, say that the same state vector, acted on by the same matrix operator(s), produces the same spectrum of secondary properties.

    Now, in a way, we have only restated the obvious in a slightly formal way: The same thing, under the same conditions, looks, sounds, tastes and feels the same.

    But we can say all that within Heisenberg’s compact and elegant matrix mechanics.

    Curiously, we also commonly model neural nets via matrices acting on vectors.

    Curious, too, the fact that engineers model colors and sounds as vectors.

    A tacit assumption here has to do with enlarging the official ontology of physics to include color, sound, and so forth. I’m pleased to report that Schrodinger came to the same conclusion in regard to this business, which I recently learned while reading his Dublin seminar, ‘On the Interpretation of Quantum Mechanics.’

    Here’s an excerpt:

    “What this something is cannot be said; by calling it matter or field or whatnot, we just give it a name. The relevant point is that it is not supposed to have any other properties but geometrical configuration, changing in time according to certain “laws of nature.” It is not in itself yellow or green, sweet or cold. If parts of it appear to us so, there is no hard, indubitable fact to make this judgment true or false.

    This view is strongly supported by our analysis of actual experimental procedure, and it is attractively simple. It carries us comfortably a long way, indeed so long, that we may have forgotten its artificiality, when we meet the obstacles that it renders unsurmountable. So it is better to ask the naive but very pertinent question right away: how do red and yellow, sweet and hot come in at all? Once we have removed them from our “objective reality,” we are at a desperate loss to restore them. We cannot remove them entirely because they are there, we cannot argue them away. So we have to give them a living space, and we invent a new realm for them, the mind, saying that this is where they are, and forgetting the earlier part of the story—all that we have been talking about till now—is also in the mind and nowhere else. But deeming it to be something else—objective reality—we run against the unanswerable question: how does matter act on mind, to produce in it the sensory qualities—and also how does mind act on matter, to move it at will? These questions cannot, so I believe, be answered in this form, and they owe their embarrassing form precisely to our having posited an objective reality which is a pure geometrical scheme of thought and deprived of everything real given by experience.”


    Well, this is to alter a fundamental assumption of physical theory in a significant way. So I’m happy to see that Oxford, Cambridge, and Yale have started up institutes and programs to address foundational issues in quantum theory—remarkable signs of life in an area that was largely moribund for many years.

    I’ll close with two little quotes:

    Whatever the meaning assigned to the term complete, the following requirement for a complete theory seems to be a necessary one: every element of the physical reality must have a counterpart in the physical theory. ~EPR

    The aspects of things that are most important for us are hidden because of their simplicity and familiarity. ~Wittgenstein

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  5. We physicists are good at taking things apart and understanding how the pieces work. Reductionism has been our game since Newton. But holism is fundamental to QM. The formalism is shouting at us, “There is only one wave function for the whole goddam thing!” But in seeking solutions to quantum systems, we focus on individual particle wave functions, and their direct products, because we have no tools to deal with functions that live in a 10^23-dimensional space.

    All this is to say that we have been looking for quantum entanglement in particle pairs because that’s what we know how to think about and to measure. But it’s possible that there is such a thing as massive entanglement on a macroscopic scale, and it’s possible that evolution has figured out how to make use of something that physicists haven’t figured out how to calculate.

  6. Would someone please apply Occam’s razor here? Where is the evidence that quantum effects are in any way necessary to explain brain functionality? Rather than inventing maybe just possibly plausible stories about quantum entanglement in phosphorus molecules, wouldn’t it be better to try to map the relationship between structure and function in the brain? This is an area where good physicists really can add some insights. See http://www.scholarpedia.org/article/BCM_theory

    • I don’t know evidence that quantum effects are “in any way necessary,” and “just possibly plausible” is a fair way to characterize the story; it is highly speculative and easy to dismiss. I find it interesting anyway.

    • I notice that my thoughts and intentions that seem so close and private are yet able to make this hand move, and I’m trying to apply Occam’s Razor in seeking an explanation. So the “simplest” explanation is that I don’t exist and these thoughts and intentions are just me fooling myself and so you see there’s really nothing to explain…or…hey, here’s an even more Occam-esque explanation, even simpler: the material world doesn’t really exist, and I’m just dreaming that I have arms and legs, and dreaming that you wrote a post about Occam’s razor and that I’m typing an answer. What could be simpler?

    • There is nothing else except these [quantum] fields: the whole of the material universe is built of them. ~Dyson

      The brain is presumably a “material” thing.* It is, therefore, a collection of quantum fields.

      QFT has often been called our most successful physical theory. It would seem to be telling us that, in regard to the brain, there’s nothing else there but quantum fields.

      And that’s kind of interesting, because the immediate objects of sensory awareness are perceptual fields — which reliably covary with their concomitant photonic fields.

      It’s really not that complicated.

      *The scare quotes are there because we all know what “material” means — until we start to think about it.

  7. Without quantum effects in the brain (1) real-time causal action is impossible and consciousness is necessarily epiphenomenal, (2) global brain zero-lag coherence/synchrony is (probably) impossible, (3) photosynthesis would be impossible and we probably wouldn’t exist. If a potato can utilize quantum coherence its likely our brains (and life in general) evolved mechanisms to do so.

    Dismiss THIS (it includes harsh criticisms and our replies)
    Hameroff S, Penrose R (2014) Consciousness in the Universe – A Review of the Orch OR Theory Physics of Life Reviews 11(1):39-78

    You’re engaging in that old refrain (referring to Penrose-Hameroff Orch OR)
    (1) Those guys are crazy
    (2) Well, its obvious
    (3) We knew it all along – forget about them.

    In an updated version of our theory (in press) Sir Roger and I suggest OR-mediated feelings drive evolution and may have sparked the origin of life.

    Stuart Hameroff

      • Thanks, I guess. So why not consider the Orch OR theory which is becoming less and less speculative and more and more based on evidence as time goes on? We were ridiculed for such outlandish proposals like warm quantum biology which are now taken as fact. Studying microtubules (prevalent in all types of cells) might lead to advances in quantum computation. In fact we changed from individual ‘tubulin’ qubits (tubulin is the subunit protein of microtubule polymers) to pathway qubits in microtubule lattices based to some extent on Kitaev and your topological quantum error correction ideas. I remember your talk at the Novartis satellite meeting after the Royal Society meeting on quantum information in 1998. You were discussing orthogonal grids and I asked if quantum error correction could apply to hexagonal lattices with Fibonacci geometry, as occurs in microtubules. You said, ‘sure, why not?’.

        I’m not sure if Posner molecules actually exist, and if they do are very rare and limited. Microtubules are everywhere in biology.

        So….why not? You could at least read our 2014 review instead of acting like we’re dead. Better yet, I’ll send you the updated version (in press) which includes evolution and implications for the strong anthropic principle. There’s no need for multiple worlds with consciousness in the universe.

        • Please enlighten me: why you search for quantum effects in consciousness (it’s obvious that all in the universe is quantum, so the science/materialism guys don’t exclude the role of quantum mechanics in consciousness) when you say that consciousness is “an essential ingredient of physical laws not yet fully understood”.
          Thank you,

  8. Your argument for saying it’s ok to call it old ‘guy’ syndrome is incorrect, just like it would be incorrect to call it crazy-old-white syndrome with the pretext that sad societal factors gave way for you to only know such a small number of original black or brown scientists as to not have one of them fit your definition.
    You can try to justifiy it with the tired pretext that guy is a more simple way to refer to anyone while not being overly abstract – more normal justification but not much better.

  9. It’s plausible to compare brain with Quantum computer.If Charles Babbage would have been alive today,he would have asked is it mainframe or supercomputer?I.e the comparison between brain with computer.

  10. Spontaneous emission of a photon after absorbing one demonstrates an experiencing, individual atom.
    Individual, because the exact time of emission cannot be predicted, it is dependant of Heisenberg’s uncertainty.
    We are a big experiencing quantummechanic atomic structure, small wonder that we can experience all kinds of sensations.

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  13. Pretty fascinating stuff. Probably I should read the article carefully to see this for myself, but I suspect that to be hard to simulate you would need not only entanglement inducing correlations, but you would need something like the entangled particles being measured in incompatible bases. It looks like the measurements there are destructive singlet-vs-triplet measurements, which might be universal depending on the state preparation, but might also be simulable using Gottesman-Knill. At this point I shouldn’t speculate further without actually reading the paper. 🙂

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  24. hello, I have read the paper and it is really interesting, I think I will enjoy doing my master research on some thing related to the idea proposed in this paper, any suggestion for a start ?? I dont really know how to start ?!

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  29. I think that we must be very careful about being “mainstream” when it comes to the avant-garde of research. Mainstream looks dangerously like dogma. Besides that, the philosophical naivete of mainstream physics is just dumb, the way they talk about “realism” for example is like pre-plato, pre-kant, the equivalent of philosophers talking about pre-newtonian physics as if relativity or QM never existed.
    QM is about objects in an abstract space, it doesn’t presupposes 3d position space, so you can apply it to all experience. Highly speculative is to assume that mind is like a Turing machine or the product of a classical, local, factual machine.

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