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Does anyone know if we understand enough about natural, generally intelligent brains to dismiss the idea that they are using quantum phenomenon for computation?

Does anyone know if we understand enough about natural, generally intelligent brains to dismiss the idea that they are using quantum phenomenon for computation? Is it unlikely for any reason?

runnerup 5y ago
I believe plenty of "quantum phenomenon" are utilized in humans' biochemistry[0]. Whether the brain "calculates" things using a method that is particularly similar to the methods used in today's quantum computers is...unlikely. It probably is "quantum" in other ways though. 0: https://www.the-scientist.com/infographics/infographic--quantum-explanations-for-biological-phenomena-65917 https://www.the-scientist.com/infographics/infographic--quan...
- saltyfamiliar 5y ago
  Quantum computers don't seem very useful yet, but brains are extremely useful (and they use much less power). Maybe current generation quantum computers would be better if they used quantum mechanics more similarly to the ways our brains use it. The article you linked mentions that entanglement and qubits are being "studied in human consciousness" but I'm not sure what exactly that entails.
  - tsimionescu 5y ago
    Ass far as we understand, out brains use quantum mechanics only as much as our processors use quantum mechanics already - the world is quantum mechanical, so our brains are as well. However, given the scale of known brain features, the temperature of the brain, and other sources of noise, it's very very very hard to imagine how the brain could be a quantum computer.
- tialaramex 5y ago
  Yes. It's unavoidably "quantum" in the sense that, as a physical machine in our universe it's subject to the rules, including quantum physics. However there is no apparent mechanism by which "thinking" could harness any interesting properties of quantum physics, it's just not happening at the right scale, like the way kids sand walls on the beach don't alter the world's tides.
  - dekhn 5y ago
    Specifically: thinking and creativity do not require the QM phenomena of entanglement, tunnelling, uncertainty, or interference, no matter how much Penrose wants it to be true. By the butterfly principle, sand walls on the beach do alter the world's tides.
  - saltyfamiliar 5y ago
    That proportions in that analogy seem way off. Every single neuron of the human brain could be utilizing quantum mechanical effects at the same time. Not very much at all like a kid's sand castle against the world's tides. I don't think anyone really understand "thinking" and quantum mechanics well enough for the mechanisms to be apparent. I mean, squirrels convert forest detritus into general intelligence. I don't understand the strong certainty against the idea that there's some physics based piece of the puzzle that we're missing.
    - katmannthree 5y ago
      I believe we've been able to model the processes behind neural firings for quite some time now, the issue is more mapping between that micro-scale understanding of how each individual piece in a 10^10 piece puzzle with 10^15 edges affects the macro-scale emergent properties of said puzzle. It's less a lack of understanding of the processes and more a complexity so great that it exceeds the grasp of our best modeling tools thus far. We can barely model the humble nematode c. elegans with its 330 neurons.
      - SubiculumCode 5y ago
        Our biophysicalmodesl of neurons are actually woefully simplistic. https://journals.physiology.org/doi/full/10.1152/jn.00360.2016 https://journals.physiology.org/doi/full/10.1152/jn.00360.20...
        katmannthree 5y ago
        Yes. The simple models are simple, the fast and large and useful models are simple. We have a lot of in vitro observations which can contribute to smaller, slower and more accurate models as your linked article mentions, observations which generally are ignored as being nth order effects when people are trying to make models which have a low enough computational complexity as to be useful. What is not missing is metaphysical quantum woo[0]. We can, have, and do observe how neurons and synapses function; the issue is that the computational complexity with current approaches is great enough to make complete neurological modeling of a microscopic worm with under a thousand total cells difficult. [0] and even if you want to take those effects into account in your electrochemical models, all they do is turn them into stochastic models. there is exactly zero evidence of that randomness being of any real value to the thing we care about, which is the emergent macro scale properties of these systems.
- neom 5y ago
  I had been doing a bunch of research on quantum biology around the time that I had the conversation I mentioned above, that's probably why at the time I wanted to discuss it with him. I think these two lectures are pretty good and I'd watched them around the time I was discussing this stuff with Jack. Quantum Biology: The Hidden Nature of Nature - https://www.youtube.com/watch?v=ADiql3FG5is https://www.youtube.com/watch?v=ADiql3FG5is An Introduction to Quantum Biology - with Philip Ball - https://www.youtube.com/watch?v=bLeEsYDlXJk https://www.youtube.com/watch?v=bLeEsYDlXJk
frabcus 5y ago
Roger Penrose’s The Emperors New Mind proposed this in the 1990s. He gave circumstantial possibilities, and I don’t think we know more than that now. As an amateur, my instinct is that the mystery of the observer "causing" wave function collapse is the best clue we have either way. I wouldn’t be surprised if we are just weighted neurons, or if we do something quantum too. I doubt the something quantum will be the same as what our quantum computers do.
- neom 5y ago
  Actually I had just done a bunch of researching on Penrose around the time I was having that conversation with Jack, in fact I think I'd watched these two lectures within a few months of that conversation: Quantum Biology: The Hidden Nature of Nature - https://www.youtube.com/watch?v=ADiql3FG5is https://www.youtube.com/watch?v=ADiql3FG5is An Introduction to Quantum Biology - with Philip Ball - https://www.youtube.com/watch?v=bLeEsYDlXJk https://www.youtube.com/watch?v=bLeEsYDlXJk
- PeterisP 5y ago
  It's worth noting that it's not the observer causing anything, but a "technical observation" i.e. any interaction with the macroscopic environment; the analogy of "observer" leads to a misleading implication that there's something special if an agent or conscious entity is doing the observation, which it is not.
- visarga 5y ago
  > Consciousness causing the wave-function to collapse isn't a very popular idea these days and there are alternative explanations, though as far as I know there isn't any evidence that it is involved or if it isn't. The wave function collapse happens regardless of whether a human or any conscious being is present, all that is needed is something does an observation. Imagine a scenario where a QM experiment is done, and the result is recorded by machines and stored as a data file. Let 100 years pass then distribute copies of the file to a million people. They will all see the same thing. Source https://www.physicsforums.com/threads/does-consciousness-cause-wave-function-collapse.806278/post-5061265 https://www.physicsforums.com/threads/does-consciousness-cau...
visarga 5y ago
Not necessary. Quantum AI is basically explaining something mysterious by something else mysterious, even when there is no indication they are related.
- HPsquared 5y ago
  Aren't a lot of AI breakthroughs like this though? "It works, but we don't know why"
  - sdenton4 5y ago
    There's no evidence that "it" is working in the first place, though.
  - visarga 5y ago
    Good point. But at least we know the ML algorithms are related to ML performance, we don't know that about QM.
bawolff 5y ago
Even if they were (big if without really any evidence), we have no idea how, so adding a quantum computer to the mix won't get us any closer to general AI. It would be like adding a classical computer we don't know how to turn on; it won't help anything if we don't know how to use it.
jowday 5y ago
Someone asked this question to Leonard Susskind once at a Q&A and he said the chances are basically zero. When the guy kept pressing on the idea Susskind got kind of exasperated and seemed like he was on the verge of calling the idea woo.
PeterisP 5y ago
The quantum phenomena for calculations require strictly limited interactions as otherwise you just get decoherence. Quantum computations inside of our brain cells are unlikely because it's relatively very hot, having random interactions which would disrupt quantum phenomena.
neom 5y ago
I don't think we know enough to know, I also don't think we know enough to rule it out, to me it's plausible, and that was generally the debate... is a quantum requirement there or not. Also as a note, this was conversation over beers with a buddy, so it wasn't HN scrutiny standard, we were getting philosophical. (I know very little about the subject so my opinions aren't much more than "fun ideas".)
edgyquant 5y ago
I think people bring up this quantum phenomenon stuff a bit too often in an attempt to add a layer of mysticism to humanity. We should only jump to that conclusion if we have some kind of proof or reason to believe so. We don’t even understand a lot of how the brain works at the macro scale yet so it’s a bit early to start saying it’s dependent on those processes (other than in the same way all physical systems are dependent on quantum phenomena.) I’m also not a neuroscientist or a physicist though, so this is just my relative layman’s take.
dekhn 5y ago
nobody needs to "dismiss the idea", the null hypothesis is that brains don't exploit quantum phenomena. In the absence of any reason for them doing so, and the lack of evidence that the do so, the onus is on the quantum brain folks to come up with better falsifiable theories.
blurbleblurble 5y ago
There's actually a whole field of study that uses tools from quantum information theory to successfully model cognitive and social situations. This doesn't require any assumptions of "quantum physicality". It just makes sense to model probabilistic, reflexive, slippery-to-observe systems with tools that were designed for this. Quantum theory has really great tools and they work well. I realize this isn't quite the answer you were looking for, but I thought it was worth mentioning. I personally think this idea that there is some obvious categorical distinction between hard "physical" quantum phenomena and classically probabilistic ones is a fallacy. Quantum theory is in some sense just probability theory with more features. More and more researchers are catching onto this and I think that's really exciting.
- ummonk 5y ago
  Surely they'd just use tools from regular information theory and Bayesian inference? Quantum theory is just one particular application of information theory, where uncertainty is directly controlled by physical processes rather than simply due to imperfect knowledge.
  - blurbleblurble 5y ago
    Quantum information comes from Von Neumann entropy, while classical information comes from Shannon entropy. Regardless of where the "source" of information/uncertainty comes from or how "physical" it is, they're related but distinctly different tools which can each be applied to both "physical" or "non-physical" systems at any scale. "Quantum" is turning out to have very little to do with how tiny or physical stuff is, and much more to do with assumptions about how observations emerge from interaction. > rather than simply due to imperfect knowledge That's the key right there... Quantum probability and quantum models don't rely on the existence of "perfect knowledge" or "underlying" objective states. States themselves are intrinsically probabilistic and contextually embedded. Measurements/observations cannot be cleanly decoupled from the states being measured, and are modelled as projections from a high dimensional space of possibilities onto some lower dimensional subspace. This kinda thing works really well for social/cognitive systems which are incredibly sensitive to measurement process. For example, when conducting polls or surveys, the ordering of the questions is well known to impact the outcome. It turns out that this can be very well modelled using tools from quantum theory, and it has been. Check out this book and all the books/papers citing it for a window into this fascinating world https://link.springer.com/book/10.1007/978-3-642-05101-2 https://link.springer.com/book/10.1007/978-3-642-05101-2
machiaweliczny 5y ago
We will only know if we can't built it. My gut feeling is that even if we use some probabilistic quantum compute it should be transferable to normal compute. Also animals vs human don't have enough difference to assume we are special.

Does anyone know if we understand enough about natural, generally intelligent brains to dismiss the idea that they are using quantum phenomenon for computation? Is it unlikely for any reason?

runnerup 5y ago

I believe plenty of "quantum phenomenon" are utilized in humans' biochemistry[0]. Whether the brain "calculates" things using a method that is particularly similar to the methods used in today's quantum computers is...unlikely. It probably is "quantum" in other ways though. 0: https://www.the-scientist.com/infographics/infographic--quantum-explanations-for-biological-phenomena-65917 https://www.the-scientist.com/infographics/infographic--quan...

saltyfamiliar 5y ago
Quantum computers don't seem very useful yet, but brains are extremely useful (and they use much less power). Maybe current generation quantum computers would be better if they used quantum mechanics more similarly to the ways our brains use it. The article you linked mentions that entanglement and qubits are being "studied in human consciousness" but I'm not sure what exactly that entails.
- tsimionescu 5y ago
  Ass far as we understand, out brains use quantum mechanics only as much as our processors use quantum mechanics already - the world is quantum mechanical, so our brains are as well. However, given the scale of known brain features, the temperature of the brain, and other sources of noise, it's very very very hard to imagine how the brain could be a quantum computer.
tialaramex 5y ago
Yes. It's unavoidably "quantum" in the sense that, as a physical machine in our universe it's subject to the rules, including quantum physics. However there is no apparent mechanism by which "thinking" could harness any interesting properties of quantum physics, it's just not happening at the right scale, like the way kids sand walls on the beach don't alter the world's tides.
- dekhn 5y ago
  Specifically: thinking and creativity do not require the QM phenomena of entanglement, tunnelling, uncertainty, or interference, no matter how much Penrose wants it to be true. By the butterfly principle, sand walls on the beach do alter the world's tides.
- saltyfamiliar 5y ago
  That proportions in that analogy seem way off. Every single neuron of the human brain could be utilizing quantum mechanical effects at the same time. Not very much at all like a kid's sand castle against the world's tides. I don't think anyone really understand "thinking" and quantum mechanics well enough for the mechanisms to be apparent. I mean, squirrels convert forest detritus into general intelligence. I don't understand the strong certainty against the idea that there's some physics based piece of the puzzle that we're missing.
  - katmannthree 5y ago
    I believe we've been able to model the processes behind neural firings for quite some time now, the issue is more mapping between that micro-scale understanding of how each individual piece in a 10^10 piece puzzle with 10^15 edges affects the macro-scale emergent properties of said puzzle. It's less a lack of understanding of the processes and more a complexity so great that it exceeds the grasp of our best modeling tools thus far. We can barely model the humble nematode c. elegans with its 330 neurons.
    - SubiculumCode 5y ago
      Our biophysicalmodesl of neurons are actually woefully simplistic. https://journals.physiology.org/doi/full/10.1152/jn.00360.2016 https://journals.physiology.org/doi/full/10.1152/jn.00360.20...
      - katmannthree 5y ago
        Yes. The simple models are simple, the fast and large and useful models are simple. We have a lot of in vitro observations which can contribute to smaller, slower and more accurate models as your linked article mentions, observations which generally are ignored as being nth order effects when people are trying to make models which have a low enough computational complexity as to be useful. What is not missing is metaphysical quantum woo[0]. We can, have, and do observe how neurons and synapses function; the issue is that the computational complexity with current approaches is great enough to make complete neurological modeling of a microscopic worm with under a thousand total cells difficult. [0] and even if you want to take those effects into account in your electrochemical models, all they do is turn them into stochastic models. there is exactly zero evidence of that randomness being of any real value to the thing we care about, which is the emergent macro scale properties of these systems.
neom 5y ago
I had been doing a bunch of research on quantum biology around the time that I had the conversation I mentioned above, that's probably why at the time I wanted to discuss it with him. I think these two lectures are pretty good and I'd watched them around the time I was discussing this stuff with Jack. Quantum Biology: The Hidden Nature of Nature - https://www.youtube.com/watch?v=ADiql3FG5is https://www.youtube.com/watch?v=ADiql3FG5is An Introduction to Quantum Biology - with Philip Ball - https://www.youtube.com/watch?v=bLeEsYDlXJk https://www.youtube.com/watch?v=bLeEsYDlXJk

frabcus 5y ago

Roger Penrose’s The Emperors New Mind proposed this in the 1990s. He gave circumstantial possibilities, and I don’t think we know more than that now. As an amateur, my instinct is that the mystery of the observer "causing" wave function collapse is the best clue we have either way. I wouldn’t be surprised if we are just weighted neurons, or if we do something quantum too. I doubt the something quantum will be the same as what our quantum computers do.

neom 5y ago
Actually I had just done a bunch of researching on Penrose around the time I was having that conversation with Jack, in fact I think I'd watched these two lectures within a few months of that conversation: Quantum Biology: The Hidden Nature of Nature - https://www.youtube.com/watch?v=ADiql3FG5is https://www.youtube.com/watch?v=ADiql3FG5is An Introduction to Quantum Biology - with Philip Ball - https://www.youtube.com/watch?v=bLeEsYDlXJk https://www.youtube.com/watch?v=bLeEsYDlXJk
PeterisP 5y ago
It's worth noting that it's not the observer causing anything, but a "technical observation" i.e. any interaction with the macroscopic environment; the analogy of "observer" leads to a misleading implication that there's something special if an agent or conscious entity is doing the observation, which it is not.
visarga 5y ago
> Consciousness causing the wave-function to collapse isn't a very popular idea these days and there are alternative explanations, though as far as I know there isn't any evidence that it is involved or if it isn't. The wave function collapse happens regardless of whether a human or any conscious being is present, all that is needed is something does an observation. Imagine a scenario where a QM experiment is done, and the result is recorded by machines and stored as a data file. Let 100 years pass then distribute copies of the file to a million people. They will all see the same thing. Source https://www.physicsforums.com/threads/does-consciousness-cause-wave-function-collapse.806278/post-5061265 https://www.physicsforums.com/threads/does-consciousness-cau...

visarga 5y ago

Not necessary. Quantum AI is basically explaining something mysterious by something else mysterious, even when there is no indication they are related.

HPsquared 5y ago
Aren't a lot of AI breakthroughs like this though? "It works, but we don't know why"
- sdenton4 5y ago
  There's no evidence that "it" is working in the first place, though.
- visarga 5y ago
  Good point. But at least we know the ML algorithms are related to ML performance, we don't know that about QM.

bawolff 5y ago

Even if they were (big if without really any evidence), we have no idea how, so adding a quantum computer to the mix won't get us any closer to general AI. It would be like adding a classical computer we don't know how to turn on; it won't help anything if we don't know how to use it.

jowday 5y ago

Someone asked this question to Leonard Susskind once at a Q&A and he said the chances are basically zero. When the guy kept pressing on the idea Susskind got kind of exasperated and seemed like he was on the verge of calling the idea woo.

PeterisP 5y ago

The quantum phenomena for calculations require strictly limited interactions as otherwise you just get decoherence. Quantum computations inside of our brain cells are unlikely because it's relatively very hot, having random interactions which would disrupt quantum phenomena.

neom 5y ago

I don't think we know enough to know, I also don't think we know enough to rule it out, to me it's plausible, and that was generally the debate... is a quantum requirement there or not. Also as a note, this was conversation over beers with a buddy, so it wasn't HN scrutiny standard, we were getting philosophical. (I know very little about the subject so my opinions aren't much more than "fun ideas".)

edgyquant 5y ago

I think people bring up this quantum phenomenon stuff a bit too often in an attempt to add a layer of mysticism to humanity. We should only jump to that conclusion if we have some kind of proof or reason to believe so. We don’t even understand a lot of how the brain works at the macro scale yet so it’s a bit early to start saying it’s dependent on those processes (other than in the same way all physical systems are dependent on quantum phenomena.) I’m also not a neuroscientist or a physicist though, so this is just my relative layman’s take.

dekhn 5y ago

nobody needs to "dismiss the idea", the null hypothesis is that brains don't exploit quantum phenomena. In the absence of any reason for them doing so, and the lack of evidence that the do so, the onus is on the quantum brain folks to come up with better falsifiable theories.

blurbleblurble 5y ago

There's actually a whole field of study that uses tools from quantum information theory to successfully model cognitive and social situations. This doesn't require any assumptions of "quantum physicality". It just makes sense to model probabilistic, reflexive, slippery-to-observe systems with tools that were designed for this. Quantum theory has really great tools and they work well. I realize this isn't quite the answer you were looking for, but I thought it was worth mentioning. I personally think this idea that there is some obvious categorical distinction between hard "physical" quantum phenomena and classically probabilistic ones is a fallacy. Quantum theory is in some sense just probability theory with more features. More and more researchers are catching onto this and I think that's really exciting.

ummonk 5y ago
Surely they'd just use tools from regular information theory and Bayesian inference? Quantum theory is just one particular application of information theory, where uncertainty is directly controlled by physical processes rather than simply due to imperfect knowledge.
- blurbleblurble 5y ago
  Quantum information comes from Von Neumann entropy, while classical information comes from Shannon entropy. Regardless of where the "source" of information/uncertainty comes from or how "physical" it is, they're related but distinctly different tools which can each be applied to both "physical" or "non-physical" systems at any scale. "Quantum" is turning out to have very little to do with how tiny or physical stuff is, and much more to do with assumptions about how observations emerge from interaction. > rather than simply due to imperfect knowledge That's the key right there... Quantum probability and quantum models don't rely on the existence of "perfect knowledge" or "underlying" objective states. States themselves are intrinsically probabilistic and contextually embedded. Measurements/observations cannot be cleanly decoupled from the states being measured, and are modelled as projections from a high dimensional space of possibilities onto some lower dimensional subspace. This kinda thing works really well for social/cognitive systems which are incredibly sensitive to measurement process. For example, when conducting polls or surveys, the ordering of the questions is well known to impact the outcome. It turns out that this can be very well modelled using tools from quantum theory, and it has been. Check out this book and all the books/papers citing it for a window into this fascinating world https://link.springer.com/book/10.1007/978-3-642-05101-2 https://link.springer.com/book/10.1007/978-3-642-05101-2

machiaweliczny 5y ago

We will only know if we can't built it. My gut feeling is that even if we use some probabilistic quantum compute it should be transferable to normal compute. Also animals vs human don't have enough difference to assume we are special.