Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Quantum Biology and the Hidden Nature of Nature

  1. Dec 10, 2014 #1
    Just came across this youtube video discussing Quantum Biology



    It features Paul Davies and Seth Llyod. It debates whether biology makes use of non-trivial quantum effects to improve performance and/or perform functions that cannot be accounted for classically. I'm posting it here and asking the following, Do you think biology makes use of non-trivial quantum effects? If so, why? If not, why not?
     
  2. jcsd
  3. Dec 10, 2014 #2

    Pythagorean

    User Avatar
    Gold Member

    It's a broad question, and I think it should be answered on a case-by-case basis. QM has been shown to be significant in at least one process of one biological system (photosynthesis in plants). I think I also remember something about bird navigation. I haven't watched the video you posted and I see a leaf on it, so maybe that's discussed.
     
  4. Dec 10, 2014 #3

    Bystander

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Photosynthesis as Pythagorean has noted, vision/eyes/rhodopsin(+other dyes), bioluminescence.
     
  5. Dec 10, 2014 #4

    Ygggdrasil

    User Avatar
    Science Advisor

    There are a few well documented cases where biological processes take advantage of quantum effects to function. Here's a link to a news feature from Nature describing a few examples (with citations to the relevant literature).
     
  6. Dec 12, 2014 #5
    I find it aggravating that the most in-your-face phenomenon in Physics is off limits to Physics. It's what Seth Lloyd referred to as the "C word". There's only one known physical condition where lots of information can exist in a single state - QM super positioning.

    So my answer is an emphatic "Yes".
     
  7. Dec 13, 2014 #6
  8. Dec 15, 2014 #7
    That article is using "Hopfield networks" or "Hopfield-like networks" to get a the "integrated information" into a small number of neurons. (The article also addresses other structures.) The authors (Balduzzi and Tononi) recognize that, for consciousness, the information needs to be integrated - and work with ways of describing that integration. Their paper reinforces the critical step in recognizing that information doesn't just add up on its own, that there needs to be some systematic way of causing this information to build up. But they only go as far as the neuron - or small network of neurons. Once at that level, you still haven't merged the information into a single state - only a collection of independent states that fit within a neuron or network.
     
  9. Dec 15, 2014 #8

    Pythagorean

    User Avatar
    Gold Member

    As far as I know, in the context of biology, the only useful aspect of information density from QM is that it allows for classical matter. The organism itself doesn't exploit the information density.

    Even in the case of photosynthesis, the advantage seems to be the speed.
     
  10. Dec 15, 2014 #9
    If you can tell me that you are conscious of more than a couple of bytes of information at a time, then that information density has affected your behavior.
     
  11. Dec 15, 2014 #10

    Pythagorean

    User Avatar
    Gold Member

    "More than a couple bytes" can easily be handled by the relevant fraction of 86 billion classical neurons each with a 7000 synapses, and each modulated by a number of second-messenger and transcription processes. Nobody denies that the classical mechanisms have QM under the hood, but this discussion of "Quantum Biology" is more about biological mechanisms that can only be handled by QM perspective and not the classical perspective (i.e. "non-trivial" QM as the OP put it).
     
  12. Dec 15, 2014 #11
    But are the many bytes of the neurons/synapses merged into a single coherent state? I think what .Scott is trying to state is that even though IIT gives a measure of integrated information, it does not provide a mechanism for which the info is integrated (correct me if I'm wrong). Fundamentally then wouldn't you need a QM non-trivial process to merge/integrate the information into a single whole state?
     
  13. Dec 15, 2014 #12

    Pythagorean

    User Avatar
    Gold Member

    But the evidence already shows that there's too much heat and to large of spatiotemporal scales in the brain to support a QM-based integration. I'm not sure either QM or classical physics is enough, but the evidence (neural correlates consciousness with respect to dynamics) implies that it will be an extension of classical mechanics, not a reduction to QM (the mountain of understanding we have of brain function is based on classical models and information theory, compared to a very tiny minority of very speculative propositions with regards to QM). What Tonini shows is that information integration (of classical components) is consistent with our expectations. You're right that it doesn't give a mechanisms, but the "dependent variable" is the dynamics and interaction of classical components.
     
  14. Dec 15, 2014 #13
    I thought the "too warm and wet" argument against QM processes in biology had been put to rest? The work in the field of photosynthesis (Greg Engel, Greg Scholes) has shown that thermal noise can assist quantum coherent energy transfer in these systems. The spatiotemporal scale concern is one that is actively under investigation.
     
  15. Dec 15, 2014 #14
    QM and relativity is the extension to classical mechanics - there is no other. So if we need an extension, it will be to QM.
    Besides, the wet and warm QM is merely a technological issue. But putting significant amounts of inform into a single state is fundementally missing from classical electronics/mechanics - eventually, HUP (QM) gets in the way.

    We haven't even started to look for significant QM mechanisms. And, as can be seen with the photosynthesis debate, it's a difficult detect and demonstrate. It's a far cry from hooking up an osciliscope to an electrode and probing the brain of a guinea pig. When we finally find the mechanism, it will be because we already know exactly what the mechanism does and what it's overall contribution is to thought. At that point, we will know exactly what we are looking for and roughly where to find it.

    Tonini's paper is useful. It shows how the information capacity of a neural net system increases based on how the neurons are designed and interconnected. But having 10 bytes classically distributed among 1000 neurons is far from having a single state. It's like writing 10 bytes worth of information onto a piece of paper and expecting the paper to be conscious of it.
     
  16. Dec 15, 2014 #15

    Pythagorean

    User Avatar
    Gold Member

    @testingus

    As far as I know, this is only true for very local events, such as the photosynthesis example.

    @.Scott

    There's really no reason to require that all consciousness must relate to one physical state as we describe it on paper. Consciousness can be a conflicting and dissociative amalgam of experience. There are many examples of this in the field of clinical neuropsychology, as Tononi pointed out.
     
  17. Dec 20, 2014 #16
    I don't really get it. Nature does what it does and nature does it in a way that we needed QM to explain it.

    No chemical bond can be explained classically. Not one thing that it does it does without QM.

    Obviously life would not be able to exist if nature had to obey classical mechanics. That's a truism.
    This lecture seems to try to explain mysteries with novel (interpretations of) QM.
    Cheat time and cheat distance? Does QM do that?
    Or are they talking about biology being able to change the planck scale?

    Do we know how biological systems work in terms of particle physics? No we do not. Right now it is already difficult enough to get inferences about the shapes of proteins. Let alone how they operate on a scale were quantum 'fuzziness' dictates and classical thinking breaks down completely.
    The lecture talks about 'we have evidence quantum mechanics' plays a role in photosynthesis. And it's physics professors saying that?

    What do they think biology is? Do they think that once one of 'their' photons hits a plant leaf it suddenly changes to a world where Calc I is all you need to explain what happens 'because biology isn't a real science and they don't do calculations'?

    Would be a truly amazing discovery when it is shown that biology can 'turn off' QM and catch photons or transfer electrons 'as if they behaved as particles'.
     
    Last edited: Dec 20, 2014
  18. Dec 21, 2014 #17
    Nature doesn't care what theory humans have developed to attempt to explain it. QM is just another man-made theory, just like classical mechanics, albeit a very successful one. It doesn't make any sense to say nature "turns off QM", QM is a theory, a series of postulates and a mathematical set of rules for manipulating information to enable humans ask and answer questions about nature. It is not a physical thing out there which nature can use or "turn-off".
     
    Last edited: Dec 21, 2014
  19. Dec 21, 2014 #18
    Of course it doesn't make sense. Did you read my post?
     
  20. Dec 21, 2014 #19

    Pythagorean

    User Avatar
    Gold Member

    We don't need QM to explain the trajectory of a cannon ball. You might even argue that a QM treatment wouldn't be successful. Likewise, the dynamics of an RLC circuit can be predicted more easily with classical electrodynamics.

    The neuron and its coupling in a network can be described with classical electrochemistry (the Nernst potential) and a classical leaky capacitor. Since the electrical activity of neurons is what we correlate with consciousness, cognition, and behavior, looking for uniquely QM effects is kind of begging the question.
     
  21. Dec 22, 2014 #20
    Since we don't know exactly what the neuron does, I wouldn't be so quick in presuming how it does it.

    Most recently, here is an article that challenges the notion of how neurons store long-term memories:
    http://elifesciences.org/content/early/2014/11/17/eLife.03896
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Quantum Biology and the Hidden Nature of Nature
  1. The Nature of Life (Replies: 5)

  2. Nature's Balance (Replies: 1)

  3. Nature's actors (Replies: 4)

Loading...