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Quantum consciousness

  1. Sep 8, 2010 #1
    Hammeroff/Penrose seem to be the two main pioneers of this (apparently radical) idea recently. The main beef against it is that coherence times will be too short under physiological conditions.

    However, recently, long lived quantum coherence was showed in photosynthesis in a PNAS paper..

  2. jcsd
  3. Sep 8, 2010 #2
    I don't see why we need quantum consciousness. We can construct a purely classical consciousness, at least in principle.
  4. Sep 9, 2010 #3
    It's an example of how great scientists can become crackpots once they go outside of their field.

    That doesn't solve the basic problem. The trouble is that quantum effects only matter at scales within cells, whereas most neuroscientists think that the important parts of brain activity happen at the connections between neurons which are too large for quantum effects to be important.

    So in order to have quantum mechanics be important in consciousness, you have to have the computations take place inside cells. One thing that I've never had explained to me is if this is true then why do sleeping pills and cocaine work. You can make me quite unconscious by putting into me chemicals that change my neutrotransmitters, and it would seem to me that if consciousness was in the microtubules, then you should be able to inject me with phenobarbital and have nothing happen.
  5. Sep 9, 2010 #4
    I don't agree that they became "crackpots". They theories are subject to scientific challenges (such as yours) and are not par to relativity-falsifying nuts raging on internet. To be labeled as crackpots as soon as you leave, to any extent, your field of expertize is counterproductive: any such theory, even false, may be valuable because it makes other people rethink they respective fields, reinforcing or widening the cracks in the logic and experiments. For an example, if there were no phlogiston theory, maybe chemistry and thermodynamics would develop at different pace?!

    First, I think we can all agree that H/P failed to convince people in key role of QM in consciousness, but the motivation for such claim is obvious; connecting superior computing performance demonstrated by quantum computers with our own brains is appealing. If not egoistic. But still, it may play any number of roles, if not calculating one. It may support calculation in key manner, just as it is supporting photosynthesis in PNAS article, taken it is true. If there were no such boost in efficiency provided by QM, photosynthesis may not be evolution's first selection for main energy conversion process on which most life is based.

    Second, I think your objection is wrong. No doubt you are aware that neurological process use electrical and chemical signals that are so inter-dependable that blocking chemical signaling (via phenobarbital, for example) render electrical signaling useless. That does not prove QM doesn't play any role at electrical part of process.

    For some times, I've been planning to read Shadows of the Mind - I think I'm gonna buy it. As for me, jury is still out there. Leaning against the case, but still ...
  6. Sep 9, 2010 #5


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    According to Penrose, consciousness involves non-computable creativity, while classical mechanics cannot involve non-computable creativity due to determinism. I'm not saying that I buy this argument, but that's roughly what his argument is.
  7. Sep 9, 2010 #6


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    More of a philosophical argument than a scientific one, really.
  8. Sep 9, 2010 #7
    What prevents you from adding some random element to classical mechanics? Say, random initial data, or some randomness in the Hamiltonian....
  9. Sep 9, 2010 #8


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    I've been over this BS already and and debunked it. And I've debunked it with respect to that paper as well (go search if you like), which does not change the situation one bit. If you think that paper changes the situation, you don't know either biochemistry or quantum mechanics.

    Short version: Nobody knowledgeable that I know of ever disputed that electrons, photons, the lightest atoms (to a lesser extent), as well as phonons and excitons behave quantum-mechanically. Which includes existing in superpositions. While we're at it: all chemical reactions are inherently quantum-mechanical, so 'discovering' quantum mechanics is involved in biochemical reactions is pretty trivial (of course, the authors didn't claim to discover that, but sensationalized versions do)

    From the biochemical or biological point of view, this changes absolutely nothing. The fact that energetic states inside an enzyme exist in a superposition at timescales that are chemically insignificant doesn't change anything in the system at-large. At the end of the process, either the photosynthesis enzyme causes a reaction or it does not, and there is no longer any superposition beyond that point, due to the same decoherence processes as before. This kind of process is so insignificant to chemistry that it's hardly been studied. Chemists in general don't concern themselves with how energy gets from point A to point B in a molecule, because they know it doesn't occur at chemically significant timescales.
    Last edited: Sep 9, 2010
  10. Sep 9, 2010 #9


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    No, but leaving your field and coming up with ideas that everyone in the field, with the benefit of years of experience and study consider insane, is crackpotty. Like many of Pauling's ideas on physiology and nuclear physics. Or Alfvén's ideas about cosmology and so on.
    I think their motives tend to be more philosophical. Often on the lines of "QM is indeterministic, so if our brains work directly on QM we cannot be predicted and that means we have free will" (I won't comment on the philosophical naivité of this statement, but it's a common idea among proponents) Of course, there's no evidence our brain works anything like either a computer or a quantum computer.
    No, because the activity in your brain, as far as our current understanding goes, is not governed by a single enzyme, or a single molecule, or even a single cell.
    Who says it was? I don't think that's the mainstream opinion. Photosynthesis is a lot more complicated than other pathways that exist. And it certainly didn't evolve easily, because nature only evolved it once. Every single Photosystem II is essentially the same. Every other light-harvesting complex (e.g. rhodopsin) catalyzes some much simpler reaction.
    QM plays a role as it always does - through chemistry. But there's nothing particularly quantum mechanical about an http://en.wikipedia.org/wiki/Action_potential" [Broken].
    Last edited by a moderator: May 4, 2017
  11. Sep 9, 2010 #10
    Um, how?

    Quantum mechanics can not compute non-recursive problems, too. It can only exponentially speed up calculations, but the class of solvable problems is the same.

    Non-recursive problems are such problems that require infinite number of elementary steps. Only time loops would allow to compute IR problems physically.
  12. Sep 10, 2010 #11
    I'm willing to accept that quantum effects are not a "cause" of consciousness, but you can't construct ANYTHING purely classical, in a quantum world. That's like saying you can construct a Newtonian rocket... you can do it according to those rules, but the result is still going to be dependent on geometric spacetime a la Einstein.
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