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Do we need quantum mechanics to explain biological stuff?

  1. Jun 24, 2015 #1
    While I have to admit the question in its summarized version seems to be not very well defined (and naive, of an easy answer), so that I desire to at least make it sound less stupid. Or at least I hope. After reading all of this it might sound even worse though (no promises).

    I like reading about possible links between what is considered 'physics' and what is considered 'biology' - the way I see it, it is physics in the "turtles all the way down" even if complexity might arise for less intuitive reasons (I won't go in depth about this last statement because my knowledge about how complexity emerges in systems is quite lacking - anyone can feel free to comment on that, though, as I see this can only add for me) that could in principle be less easily perceived.

    Once I read one thing that gave me quite a delightful thought: replication couldn't be a quantum mechanical thing because of the no-cloning theorem.

    To me this is quite a bizarre statement, because I think this has echoes of ideas contained in book like "What is life?" by Schrödinger and other very wierd or provocative stuff that bright people might write from time to time - and that, by the way, might be quite awfully wrong about the subjects they are dealing with. While I haven't read this book - even if I plan on doing it soon - I've read passages that amused me.

    But analysing the no cloning statement from the point of view of someone completely ignorant about the (for instance) DNA replication process (if you are more of an expert on this field, you might comment on the whole replication thing as well), I started thinking 'Well.. there could be some sense in this'. Maybe such a statement would imply necessarily that there is something quite classical going on replication as when a DNA molecule replicates itself there are tiny errors (which I'm going to assume are random or of unknown origin - but if we know this nowadays, I'd love to read about it), so it is most of the times basically equal to its originating a molecule that is chemically equal. This last consideration always raises the question: BUT isn't chemistry "just" applied quantum mechanics?

    (I'm not trying to imply a chemist is a lesser being - maybe from the point of view of the "ultimate practical layman" they might be considered much more important and essential to society than physicists are, even though I honestly think is being fascinated by other things that drive people to one field or the other - but I don't know anything in chemistry that could in principle be OUT of quantum mechanics - and THAT would surprise me very much if existent)

    So the question would become something like (the not well defined following question): what of quantum exists in a replication process? Is there a echo of quantum mechanics or could it be simply dismissed as almost entirely classical? Are errors quantum or classical? Is there any link between those conceptual ideas?
    I hope those questions are actually important, by the way, and, if one may, one could point out why those questions would be bad questions, as I do not ignore the possibility of them being a little too soon or too stupid to be asked.

    (Now let me digress a little...)
    I wonder those things because one of the 'great doubts' human beings have is connected to replication: What is life? What was the origin of life? (This one question is probably not going to be solved while I'm alive, but I feel I'd be "amused enough to see da Vinci painting part of the Gioconda", even of I'd prefer to be da Vinci myself...)

    After reading a book by Freeman Dyson about the origin of life (being myself a big fan of the whole concept of biological evolution and its scientific importance), I was left with the impression that there are problems in replication that were left to be read by the book's reader (yep, that is me) - shamefully, I have to express my ignorance about this aspect, having not EVEN searched for articles about it, just so I could satisfy my curiosity - as there were problems with a lot of those very speculative ideas (which, last time I checked, inspired other people working on those problems, which left me with the quite pleasing sensation that we are NOT ignoring this 'great doubt' for lack of ideas on how to deal with it - I even found articles about exploring computationally those ideas).

    Other problem I could also see, from the highness of my ignorance, were how to test experimentally those ideas, how to develop methods to test and date samples as old as 3,8 billion years, how could the primitive life exist without a cell to provide an internal environment to the 'metabolism' or 'the lots of chemical reactions which would allow DNA to ever be a thing' (in case the DNA-RNA world were confirmed), or how did the cell environment ever formed (in the case of a garbage-bag world - which, by the way, seems to be more reasonable to me - and as far as I can tell the questions we could answer more closely are about the plasmatic membrane, as we have a wider expertise in making oil bubbles than 'very hardcore DNAs' in the lab).
    (Digression finished.)

    So after this long motivation I hope to have given enough reason to make people say: well those questions are not THAT crazy and nonsensical...

    And, just so that I finish this even crazier, I'll ask this: how much quantum are human senses?

    Because we acuse ourselves of always perceiving the world classically because we are classical beings: we are local, we do not seem to interfere, it doesn't seem reasonable that a wavefunction specifying the state of something could go through a process similar to 'the collapse'... But that seems to contradict the whole "quantum mechanics is always simulating classical mechanics because of decoherence" thing.

    I know biology can be viewed as 'emergent from chemistry' in much the same way as chemistry can be viewed as 'emergent from physics' (and you might go beyond that if you want, but I do not hold this "beyond" view, at least not all week long...), so, loosely speaking physics implies biology even if "More is different.".

    This last part is motivated for the fact that I think (sometimes) we could maybe in the future make extreme body alterations to perceive the 'quantum part of the world more', if that even makes any sense. Or would that be entirely not necessary as we should be "as quantum as it could get", because 'physics implies biology'?

    Hopefully this was not long enough to be boring or too crazy so that people could not understand me... If people insist, I might break this into a more digestable content.

    1) Classical vs Quantum can mean lots of things. For me quantum and non-classical can be assumed to be similar in this context, while the concepts of wave function, decoherence, entanglement, superposition, etc., could be assumed as the quantum things; classical would be locality, Newton's laws, classical electromagnetism, 'classical' thermodynamics (amoung other stuff).
    2) I can clarify what I mean before being crucified... This is just the whole feeling I have. It is not meant as an absolutely polished world view (it has PRETTY BIG INCONSISTENCES, and might even have paradoxes within it, so it would not seem to be, scientifically speaking, or bigger worth because of imprecision).
    3) I leave the reader free to comment on only parts of my questions.
    4) If you consider this whole thread "quackery all the way", please, I'd like an explanation for such position.
    (Feel free to correct grammar. English is not a language I was taught since I was a kid...)

    Thank you, and hopefully there will be anyone reading and replying.
  2. jcsd
  3. Jun 24, 2015 #2


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  4. Jun 24, 2015 #3
    Thank you for your reply. Honestly I did not expect anyone to reply so quickly. I'm glad with it.

    - I'd like to point out that I'm marginally aware of the fact that the sense of smell is "quite quantum in its mechanism", because of those news you told me to read - honestly I think it would be better to read the original paper at this point (I have an OK understanding of quantum open systems), but I'll be able to find it easily with your link. Thanks. (I still keep having the problem with the "quite quantum", though... How to make that more objective...)

    - I can't access http://physicsworld.com because I'm not subscribed... I hate having to subscribe to everything... But I might as well do it.

    - "Quantum wierdness": I've read (diagonally) some of the following articles:
    PRL 111, 230503 (2013)
    The Journal of Chemical Physics, 129(17):174106, 2008
    (So, yes, I'm aware there is someone researching the field, and what that means from the application's point of view... I might as well read all those papers, then, even if my initial post was more about discussing things and topics)

    - I liked the last link's passage: "If quantum tunnelling is an important mechanism in mutations, is quantum mechanics going to somehow answer some of the questions about how a cell becomes cancerous?". I also don't know what to think about it.

    I'm curious, though: what technique did you use to read all I wrote SO FAST. I NEED to know that! I mean, I know people that read fast, but damn...

    Your reply made me realize that I should have narrowed my question (but what precisely I wanted to discuss is not THAT clear in my original summarized question, even if you hit some points I wanted to discuss, because my chemistry and biology are somewhat rusty...). Sorry about that.

    I'm impressed how fast and precise you were, though.

    OBS.: I almost deleted the thread because of another thread you (yes, yourself) answered in this subject - and, as this research area is not that old it could be qualified as speculative... (I might point out that the guy that initially posted the thread was speculating in a little empty fashion...)
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