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A New Spin on the Quantum Brain (quantamagazine.org)
78 points by digital55 on Nov 2, 2016 | hide | past | favorite | 43 comments



The piece[1] from John Preskill linked in the article has less fluff and is more informative, IMO.

Given Preskill is director of the IQIM, and Fisher is on its faculty, he may have a promotional agenda; but he has an impressive pedigree[2] - I don't have the knowledge to directly evaluate the hypothesis myself, but if Preskill considers it worth investigating, I'd refrain from betting that it's nonsense!

1: https://quantumfrontiers.com/2015/11/06/wouldnt-you-like-to-...

2: https://en.m.wikipedia.org/wiki/John_Preskill


Thanks for the link.

I just watched https://www.youtube.com/watch?v=ku6jVUJONZAm which is a recent lecture in which Matthew Fisher goes into some detail for a predominantly physics theorist audience. He doesn't actually finish his whole talk, but what he does cover is still pretty interesting to me as someone just trying to follow along with my rudimentary recollections of college quantum mechanics.

So {ortho,para}-pyrophospate is a big part of his grand hypothesis. This is analogous to {ortho,para}-water, something I hadn't heard about but which is apparently pretty famous, except with phosphorous instead of hydrogen. And as part of discussing this he mentions a study, presumably http://www.biophys.ru/archive/h2o-00011.pdf, that claims that passing water vapour through charcoal can change the ortho/para ratio from the normal 3:1 to 12:1 and then down to 2:1 for hours. That's just amazing to me, that liquid water can effectively remember a prior interaction for hours. Like that Japanese crank scientist's claims about water memorizing poetry or something, but, you know, actually real.

Fischer's proposed explanation is that ortho-water (and orth-pyrophospate) can't "sit still" because of the way that the aligned nuclear spins of the hydrogen (phosphorus) atoms cause the angular momentum to be quantized in a way that locks the angular velocity to be non-zero. And that discourages the ortho-molecule from being adsorbed or participating in catalysis -- measurable things which can clearly have biological effects. And from the nuclear spin, which is otherwise very long lived!

That's just crazy! Metastable water lasting for hours? I just smiled.

The other stuff may even be a red herring, but even this basic idea is so exciting if true. Here's a suggestive quote from the Russian article:

> Ortho and para water are expected to have notably different physical-chemical properties and, like ortho and para hydrogen, have different magnetic properties. The absence of the magnetic moment in para modification implies its complete insensitivity to the magnetic field, which could be of use in magnetic resonance imaging. The OP separation procedure realized is quite straightforward and may occur in nature—in soil, atmosphere, living organisms, and cosmic objects. The scope and the role of this phenomenon are yet to be studied.



If there were some quantum process involved in our neurons, the next question would be, when did it evolve? Is it in sponges? We actually have quite complete simulations of neural networks of some lower lifeforms. It must have then evolved sometime between the lifeforms we can simulate and ourselves. If that's the case, you'd expect some discontinuity in functionality vs volume. You don't see that anywhere.

And as stated in the article, it seems to be a solution in search of a problem.


It mostly seems to be another place for dualists to hedge their bets, without a whole lot to offer anyone else. Maybe that will change, but I doubt that will be anytime soon.


Really a poor place too, since we can simulate quantum behavior, albeit inefficiently.


I'm basically pro quantum-brain (being honest about my bias here) but am fairly pessimistic about our ability to actually detect such processes in the brain. It's such an interesting question though, and this is what motivated me to do a PhD in quantum information theory. Our ability to detect entanglement is at the moment extremely rudimentary. It appears that detecting entanglement is about as difficult as creating entanglement, and we suck at this also. Most of the proposals for quantum computing require vast amounts of entanglement, and in such a way that any observation of a small sub-part of the system cannot detect the encoded information. So, we may need a quantum computer to be able to detect a quantum computer.


Well, save some immense breakthrough, we won't detect anything, that's for sure. That's why it's so important to live, work, educate in a sustainable fashion ;) . Let's face it, we don't know a whole lot about anything. Thankfully, many people are taking up the challenge. Sadly, many, many more just don't get it. Sorry for this rant, it's late.


I've long suspected that the brain might be using quantum computing techniques. It's a good physically plausible explanation for how you can get more compute than a modern at-scale data center on 40-60W of power and in a volume about the size of two beer cans.

IMHO there's really only three possibilities:

(1) There exist ridiculously efficient learning, search, and other algorithms that have not been formally discovered that allow the brain to do what it does on a lot less compute than we think. P=NP would be the extreme case of this.

(2) The brain is a quantum computer or is doing something equally exotic.

(3) It's supernatural, and the brain is only like a radio receiver for something in another realm. (Or the universe is a simulation, etc., etc.)


1. Seeing as we have never made a computer able to be conscious, or hear/see/smell/touch as good as us, or reach the same power-efficiency I'd say there is an absolutely an enormous amount we still don't know.

2. Life started off as the smallest thing possible (atom/quark/something smaller) and grew upward into cells, then multi cellular and so on. All the while being present in the natural world and getting feedback from the best test environment there is. In comparison our computers started off as bricks, and over time we've slowly shrunk them down to what we consider small. But we still have nothing on evolution.

3. The unknown can often appear like magic, but as the rise of neural networks in computing has shown, we are ever so slowly unraveling the secrets of the brain. Image recognition has come a long way compared to 10 years ago, and the techniques that are working in machine learning now are changing the way neuro-scientists interpret the structure of the brain.


Or (4) the brain uses specialized electrochemical processes to perform computations that are not well addressed by traditional computing paradigms, which are designed to outperform the brain in areas in which it is naturally weak.


I think this is a variant of (1). Anything like this should be able to be computationally approximated efficiently.


Why? That claim seems baseless to me.

My GPU can compute things efficiently that my CPU can't, and vice-versa. Historically, analog computers have been able to compute things efficiently that digital computes could not, and vice-versa.

Why should a digital computer be particularly adept at computing that which a dense electrochemical network can?


Well, we don't really build 3D CPUs with 100 billion transistors and 100 trillion connections (of variable strength) between them. Not even close.


Not yet, but we've tried and managed to build neural network processors with thousands of nodes and millions of interconnects.

100 billion transistors isn't a lot. The interconnect is a beast, but as we get better at layering chips this might not be a big deal.

The thing about biological neurons is they run at very, very low speeds, on the order of KHz, which means the heat normally associated with high transistor densities is a non-issue. You could create a chip so dense it's basically a cube without concern it was going to melt down.

The biggest problem with replicating this sort of thing in silicon is that the neurons reconfigure themselves physically, something not possible with today's VLSI technology.


I think you're very wrong in your estimates. We don't have the technology that allows for 1000 (variable-strength) connections per transistor with 100 billion transistors, not even remotely close, not at 1kHz, not at 100Hz. We absolutely don't know how to do that, even without the requirement to have it small.

If we did, we probably would have built something like that - Google or Apple would easily throw $100M at that project.

You're probably talking about IBM's TrueNorth (http://wikipedia.org/wiki/TrueNorth), which simulates 1M neurons with 256 connections each. So yeah, it's the right direction, but it's 9 decimal orders of magnitude away from the human brain. And that was like a $10-20M project. If you just scale it linearly to 100 billion neurons, it will cost more than Google/Apple is worth.

Realistically, if improvements continue in the exponential fashion, maybe in 4-10 years it will become achievable without going broke.


I think we have all the technical understanding we need to attempt such a thing, but the R&D costs for trying to get this crazy process to work would be astronomical and way beyond the budget of most university labs. I'm speaking mostly in terms of theoretical ability.

We have large scale FPGA devices. Adapting this to be not just reprogrammable in a formal capacity, but constantly self-reprogramming isn't a huge conceptual leap even if it is an enormously complicated thing to prototype and get working.

This is just how the technology behind the transistor made modern computers possible, we've just been iterating and refining on the same basic principle ever since, even though some of those iterations are very painful and expensive to get working. See the current pains around 10nm processes.

When I say we have the technology I don't necessarily mean we have the will or the budget to pursue it. As the costs come down it's inevitable someone will find a solution that's not billions of dollars, but instead mere hundreds of millions.

We're a long way from a proven, working design and process, but at least we can make such a thing, theoretically speaking.


The largest scale FPGA we "have" is probably UltraScale VU440, which you can't really buy yet. It has 4.4M logic units. Again, that's 6 decimal orders of magnitude on the number of neurons alone. Not sure about connectivity architecture.

That's maybe enough to simulate the cockroach brain.

http://wikipedia.org/wiki/List_of_animals_by_number_of_neuro...

Don't get me wrong, I really really really want this to happen. I just doubt it will happen in the next 3-5 years.

There are other challenges, main one being creating the right connections. It took a long time for the evolution to create and perfect our brain. And it was a highly parallel process too.


Or perhaps the brain is less impressive than you think.


Our current computing technologies rely on a hard boundary between two states and ensuring that they are sufficiently far from any noise boundary that an error is very unlikely even with many billions of elements operating many billions of times per second. Neurons operate very differently and there is reason to think that they could compute at a much much higher efficiency.


There's the possibilities that the brain leverages a form of computing that is unlike our own. Similar to how algorithm classes differ between classical and quantum computing, there may be some esoteric form of doing 1+1 that we haven't yet explored.


With regards to (1), what about DNA-based squishy computing systems that solve TSP and the like at a rate far faster and with much lower energy usage than traditional silicon could do it?


What do you think about the idea that the brain is analog but a computer is digital? It seems to me that would give the brain a huge advantage.


I think there's a bit of 3.The Infinity.


Crazy or not, the fact that he brings up testable hypothesis is reason enough for further study.


The article makes it sound like "quantum decoherence" was the "daunting obstacle that has plagued microtubules" as a concept. This is a lie. What has plagued the concept is that there is no evidence for it whatsoever. Microtubules are a basic structural building block of a wide variety of cells, and they have not been shown to take part in information processing (apart from sometimes acting as rails for molecules to travel along), much less have they ever been demonstrated to have any kind of "quantum" effect. Articles like the one here are lying to you.

Quantum consciousness is a presuppositional pseudoscience that starts with the assumption that cognitive processes (or "consciousness" whatever that means) cannot possibly be of biochemical origin, and then works through different scenarios based on that until the proponents find one that can't immediately be discredited for a while. Just because something can't be disproven doesn't mean it's true though, not by a long shot.

Do quantum effects play a role in chemistry? Yes, where interactions between molecules and actual quantum phenomena are expected, for example as postulated for the chlorophyl molecule. But nothing in actual, serious neuroscience has so far suggested that neurons use "fragile quantum states" to compute anything.

It's also important to understand what the people proposing the different flavors of quantum quackery are actually saying: their thesis is that there is a metaphysical property called "consciousness" inherent to the universe itself, and that brains act essentially as antennas for this cosmic phenomenon. Despite the utter baselessness of these claims, people are still vigorously believing in this ever since Roger Penrose famously lost his mind to it and Deepak Chopra started selling esoteric books about it.

Quantum quackery is an insidious new age philosophy aimed at exploiting the willingness of humans to believe they are special and beyond the mundanities of the rest of the universe.


What strangely passionate language in response to mere hypotheses which do actually suggest experiments the results of which may show 'it's time to give up on the notion of quantum cognition altogether' or not. The impression is that even suggesting such ideas is a form of moral turpitude. Weird!


I'm with you, stinks of classical scientific elitism, it's intended to dissuade challenges to the status quo, in denial that much of the great progress in science have been achieved by individuals who opened themselves up to criticism in order to progress thought by doing exactly that. Shutdown!



There's a difference between cognition and consciousness. It's generally accepted that cognition is caused by electrochemical processes in the brain, the exact details of which are still to be worked out. However, there's no generally accepted, or even widely accepted, theory of consciousness.

I think that consciousness might be necessary to make quantum measurements, though. So did Eugene Wigner. This suggests to me that consciousness might have something to do with quantum mechanics at a fundamental level. Exactly what the connexion is, I don't know. I don't think it's helpful to point to particular quantum processes (possibly) taking place in the brain and claim they cause consciousness, because that still wouldn't explain how quantum phenomena give rise to consciousness.


That's because consciousness - at least in the way it's being used here - is not a scientific term at all. What people think it might be isn't reason enough to postulate a hugely fantastical cosmological mechanism where so far none has been shown to exist.

I don't really protest against your belief per se, but since you're making claims about reality that are designed to sound scientific when they really aren't, I feel compelled to voice disagreement, unpopular as it might be in this environment.


> That's because consciousness - at least in the way it's being used here - is not a scientific term at all.

It's not scientific because it concerns subjective experience, i.e. qualia, which are not measurable or observable by someone else. All an observer can do is to observe how the subject reacts. We could either leave consciousness to philosophers (who haven't got much further than Plato did), or expand science to include subjective experience.

> What people think it might be isn't reason enough to postulate a hugely fantastical cosmological mechanism where so far none has been shown to exist.

Agreed.

> I don't really protest against your belief per se, but since you're making claims about reality that are designed to sound scientific when they really aren't, I feel compelled to voice disagreement, unpopular as it might be in this environment.

I'm not advocating any "new age" world view here. My position is similar to that of David Chalmers, namely that there is something which remains to be explained. I have no particular views on how.


There is no generally accepted definition of consciousness that is precise enough to begin forming a theory, so it's not surprising that there is no such theory.

As far as I'm concerned, "consciousness" is a bogus term that will disappear once we understand the brain better.


> I think that consciousness might be necessary to make quantum measurements, though.

What is the evidence for this statement, besides the tautological idea that consciousness is necessary to make any measurements, if we consider "measurements" to be a conscious process?


I'm not a big fan of this brand of dogmatic skepticism.

I've skimmed through the paper, and from my limited college level physics, it seems like a plausible theory. Plausible enough to be worthy of publication and a modest amount of funding for further exploration.

There have been interesting conjectures in mainstream science about useful quantum effects in biology. Even neuroscience. (magnetic senses in some birds, for example). And since we don't know the tinest bit about how the brain functions, simply ruling out quantum effects is as ignorant as saying the brain solves P=NP. Just admit we don't, as a species know.

Also, I would suggest you read the article and the paper. There's little in there about consciousness.


> There's little in there about consciousness.

The article is more upfront about it. The reason why the paper doesn't lean on that too heavily is so it can evade scrutiny.

> I'm not a big fan of this brand of dogmatic skepticism.

I don't understand why skepticism about most things is okay, but when it comes to doubting claims about a supernatural "quantum" effect without any experimental evidence pointing to its veracity, that's suddenly considered too skeptical?

> Just admit we don't, as a species know.

Exactly! That's why it's not okay to just make stuff up and assert it must be true because it jibes with your spiritual worldview. We don't know if the proposed quantum effects exist, and until someone shows they do, there is no reason to believe so.

It's also worth noting that the proposed quantum woo doesn't solve any outstanding problem in neurobiology, they just love to make it look that way by having it address self-referential issues. All that crap boils down to proclaiming that the actual open questions in neurobiology are unanswerable because an inherently inscrutable magical field does all the real work.


I think people are attracted to "quantum consciousness" because it's currently the only plausible physical mechanism of free will. Essentially all of society is structured around the assumption that the participants have bona fide choices to make.

That could be wrong, but it's certainly not a fringe belief. Combine the belief in free will with the belief that physics is mostly on the right track, and it leads directly to quantum phenomena being a necessary part of the explanation.


TL;DR “We know fuck all about consciousness, but it can't possibly be anything special.”


That's a grossly ungracious summary, but yes: extraordinary claims require extraordinary evidence. You need to show some evidence of specialness first, otherwise it's just wishful thinking.

I suspect the "quantum brain" movement is in part so popular because it tricks people into thinking its claims are not extraordinary. That's why I speculated that its insidiousness comes from the fact it's a New Age pseudoscience which caters to people's pre-existing sense of superiority over the rest of the cosmos. I contend that quantum spirituality holds little appeal for materialists.


Like literally 100% of all humans -- billions of people -- have attested to the experience of consciousness. Directly. Constantly. Not in a vague, "sometimes I think I feel something" way, but literally everyone feels it.

The claim that it must not exist [1] despite that overwhelming experience, is the extraordinary claim. I don't know what consciousness is or does, and perhaps it doesn't actually exist, but the belief that it must not exist because if it did exist that would make reductive statements about the brain a little harder, is a religious belief. It's "I can't explain this and it's inconvenient to what I want to believe, so it must not exist."

[1] Or de facto not exist, as in the hand-wavey claim that consciousness is some kind of byproduct of any sufficiently complicated system that arises from a totally unclear mechanism to no purpose or result.


Why the particularly unsubtle strawman? Nobody in this thread has made a claim that remotely resembles "consciousness does not exist" or "consciousness is a byproduct of any sufficiently complicated system". Those are both totally different from "consciousness is, or results from, a biochemical process".

I think the argument you're making is much more reasonably applied in the opposite direction. The fact that we don't know exactly how consciousness works is no reason to jump to conclusions like "oh, it must be quantum-mechanical and/or incomputable", just like the fact that we don't know exactly how life evolved is no reason to say "oh, God did it."


> My cynical prediction is that if quantum-effects are part of the brain, it will only be in a practical, philosophically-boring way.

> So they may be essential to basic plumbing shared by many species, but not otherwise a game-changing factor for "consciousness" or "intelligence"


This reminded me of talk by David Mermin, about Michael E. Fischer: an important statistical physicist and the father of Matthew Fischer, as they mention in the text.

As with almost everything David Mermin writes, I specially enjoyed this talk: "My Life with Fischer" [0]. In this talk he describes how great, but scientifically 'unforgiving', Michael Fischer was, and how he raised the standards and quality of work of those around him. If he has discussed this successfully at length with his father and if his upbringing instilled in him some of the qualities Mermin attributes to his father, Matthew Fischer should be on to something interesting.

Let me share some quotes from that speech:

"Wagner and I had tried to explain to Michael that an argument of Pierre’s could be adapted to prove that there could be no spontaneous magnetization in the 2-dimensional Heisenberg model. I hadn’t known Michael for very long at that point, and one of the first things I learned was that you should think twice before claiming to prove something in front of a man who encourages postdocs to show that the free energy exists. He didn’t believe a word of it. Spectral functions, indeed! How did we know those frequency integrals even converged? It soon became evident that we were dealing with a man who knew nothing about quantum field theory, didn’t care one bit that he didn’t, and was convinced that we would be better off ourselves to forget it. Immediately.

So in the face of this astonishing attack, we worked backwards, unbundling the result from the conceptual wrappings in which it was enshrouded by some of the great thinkers of the previous decade, peeling off layer after layer, day after day, in the face of unrelenting skepticism, until finally we had it down to a trivial statement about finite dimensional matrices.

And then an astonishing change took place. “Publish!” he practically shouted, “it’s very important!” and having learned what it was like to be at the end of a Michael Fisher attack, I suddenly learned what it was like to have him on your side. Freeman Dyson came to town. Michael introduced us. “Mermin and Wagner have proved that there’s no spontaneous magnetization in the 2-dimensional Heisenberg model,” Michael proudly informed him, as Herbert and I basked in his admiration. “Of course there isn’t.” Dyson responded. “But they have proved that there isn’t” Michael insisted. One Dyson eyebrow may have moved up half a millimeter in response. No matter. I was hooked on arguing with Michael Fisher. My life would never be the same."

On Mermin and Ashcroft's textbook (one of the best in the field):

"One person, however, has influenced almost every chapter. Michael E. Fisher, Horace White Professor of Chemistrry, Physics, and Mathematics, friend and neighbor, gadfly and troubadour, began to read the manuscript six years ago and has followed ever since, hard upon our tracks, through chapter, and, on occasion, through revision and re-revision, pouncing on obscurities, condemning dishonesties, decrying omissions, labeling axes, correcting misspellings, redrawing figures, and often making our lives very much more difficult by his unrelenting insistence that we could be more literate, accurate, intelligible, and thorough. We hope he will be pleased at how many of his illegible red marginalia have found their way into our text, and expect to be hearing from him about those that have not."

"What does Michael Fisher do when he checks into a hotel room for a night? He rearranges the furniture. He’ll rotate the bed 90 degrees, put the TV in the closet to make more room on the desk, carry the desk over to the window to get more light. He is an inspiration to me. Often I find it valuable to ask myself at difficult moments, what would Michael do? This strategy is not to be confused with that of the “What Would Jesus Do?” movement, though a comparison can be interesting. Often the two questions can lead to quite different answers.

Let me give you a recent example of the benefits of asking “What would Michael do?” A few years ago I was at the annual meeting of the Danish Physical Society which took place at a small conference center south of Copenhagen. Each conferee had a little apartment with a tiny attic. Downstairs was a living room and bathroom. Up a narrow ladder was a built in bed in a room with no light. Since one used the apartment only at night this was an irritating arrangement. I don’t know how Jesus would have coped, but it was pretty clear to me what Michael would have done. So I dragged the mattress and bedding down the ladder, remade the bed on the living room floor, and never climbed up to the attic again. This solution would not have occurred to me if I had not asked myself ”What would Michael do?”

The next day various Danish conferees complained about the arrangement. Ah, I said, under such trying circumstances you should always ask yourself what Michael Fisher would do. That night the air was filled with matresses hurtling down ladders. I believe there is now a flourishing ”What Would Michael Do?” movement among the Danish physicists."

[0] https://arxiv.org/abs/cond-mat/0211382




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