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Sense of Smell Tied To Quantum Physics?

SpaceAdmiral writes "A controversial theory that proposes that our sense of smell is based not on the shape of the molecules that enter our nose but on their vibrations was given a boost recently when University College London researchers determined that the quantum physics involved makes sense. The theory, proposed in the mid-1990s by biophysicist Luca Turin, suggests that electron tunneling initiates the smell signal being sent to the brain. It could explain why similarly shaped molecules can have very different smells, and molecules with very different structures can smell similar." Turin has now formed a company to design odorants using his theory, and claims an advantage over the competition of two orders of magnitude in rate of discovery. The article concludes, "At the very least, he is putting his money where his nose is."

9 of 169 comments (clear)

  1. Raised eyebrows... by BWJones · · Score: 4, Informative

    I am going to be very skeptical of this and would not be tossing any money into a private company to study this just yet. The olfactory system is well capable of distinguishing many small molecules, even those that are very similar using a variety of well known and well understood processes just as in the immune system. Look, a Nobel prize was awarded back in the 30's for the discovery that IGGs can recognize even racemic molecules such as L and D forms of glycine even and the olfactory literature is just as rich. The biggest problem however, with the UCL approach is that it completely ignores years of cortical, subcortical and psychophysics data. Furthermore, there is no effort or model in their work that might explain how the signals would be transduced into cortical/subcortical signals or how they account for potential noise in the system. Their claim that signals can be translated through tunneling in a biological system which likely swamps those potential signals with noise is what really troubles me.

    I am not saying that they should not do it, or that they are absolutely wrong, as it is possibly interesting. Rather all I am saying is my eyebrows are raised at their claims.

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    1. Re:Raised eyebrows... by ywl · · Score: 5, Insightful

      I am a neuroscientist who used to work on olfaction.

      His theory is unconventional but it didn't break any known biological principles. Odors are detected by olfactory receptor *neurons* located on the olfactory epithelium inside the nose (for vetebrates). There are some olfactory receptor *molecules* on the membrane of these neurons - to the confusion of most people, both the neurons and molecules are sometimes called "olfactory receptors". The consenses for the last decade is that these molecules recognize the shape of odor molecules through chemcial interactions. The binding of the odor molecules to the receptors changes the membrane potential of the olfactory receptor neurons which then transmit the information to the brain.

      What he is proposing is instead of, or in additional to, the chemical interactions, the olfactory receptor molecules can recognize the odorant molecules through quantal properties. It's unconventional but it is not totally implausible. The interactions between receptor molecules and agonist (the molecules that bind and activate the receptors) are molecular level events. I'm not a quantal physicist but weird things could perceivably happen at those levels. And after the olfactory receptor molecules being activated, the signal goes to the brain in the same way as the conventional theory.

      The weakness of the theory is more since it's an unconventional claim, it needs more than usual proof. The experiment is not hard to do and after ten years, I haven't heard of a single high profile experimental paper to support it (I could have missed it). So, it probably should be classified as a neat but unproven theory.

    2. Re:Raised eyebrows... by alkaloids · · Score: 5, Informative

      IGGs can recognize even racemic molecules such as L and D forms of glycine Ah, glycine is um, not chiral. Therefore you can't have an L or a D form, nor can you have a racemate... Close though! You were really unlucky, as glycine is the only AA that's not chiral.

      As to the rest of the comment, I'll raise my eyebrows at it. I'm thoroughly skeptical that tunneling would be involved in smell though, but it would be amazing if it were. We'll find out soon enough I'm sure.
    3. Re:Raised eyebrows... by BWJones · · Score: 4, Interesting

      Dammit! Mad props to you as I was thinking alanine. That of course is exactly why Slashdot gets you in trouble. You type stuff in off the top of your head to get your entry in and sometimes you get it wrong. The cool thing is that there are folks on Slashdot that will catch you.

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  2. Been rooting for this guy! by RobertB-DC · · Score: 4, Insightful

    I remember reading about this guy (probably on the Slashdots) years ago, and I hoped that this would be one of those rare cases of someone who is rejected by the "scientific community" and then goes on to success. There are so many scientists out there that end up on dead-end roads (I'm looking at you, Cold Fusion), that it's nice to have a reminder that there's still reason to explore.

    For proof that success is the best revenge, just check out the company's product list. They're making a killing by creating replacements for aromatic allergens.

    I guess one thing that made me think he was on to something was his reaction to the scientific community's snub -- one response I recall likened a quantum-mechanical sense of smell to "food being processed in the stomach by nuclear reactions". He did NOT go around telling the world that the scientist cabal was out to get him, or that the perfume cartel was conspiring to suppress his work. He simply went about building a successful business by *using* his hypothesis to create and license useful, concrete products.

    You know, I think this is why we have patents in the first place. Not so megacorporations can trademark "business practices" -- if I hear another insurance company or bank describe their latest gimmick with a "patent pending" disclaimer I'm gonna puke. It's so some little guy on the right track can take a risk and come out on top.

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  3. Hmmm by Anonymous Coward · · Score: 5, Funny

    Does that mean that Schroedinger's cat may or may not smell like a corpse if it's dead?

  4. Re:tied to quantum physics by Oriumpor · · Score: 4, Interesting

    A poet once said, "The whole universe is in a glass of wine." We will
    probably never know in what sense he meant that, for poets do not write to
    be understood. But it is true that if we look at a glass of wine closely
    enough we see the entire universe. There are the things of physics: the
    twisting liquid which evaporates depending on the wind and weather, the
    reflections in the glass, and our imagination adds the atoms. The glass is
    a distillation of the earth's rocks, and in its composition we see the
    secrets of the universe's age, and the evolution of stars. What strange
    array of chemicals are in the wine? How did they come to be? There are the
    ferments, the enzymes, the substrates, and the products. There in wine is
    found the great generalization: all life is fermentation. Nobody can
    discover the chemistry of wine without discovering, as did Louis Pasteur, the
    cause of much disease. How vivid is the claret, pressing its existence into
    the consciousness that watches it! If our small minds, for some
    convenience, divide this glass of wine, this universe, into parts --
    physics, biology, geology, astronomy, psychology, and so on -- remember that
    nature does not know it! So let us put it all back together, not forgetting
    ultimately what it is for. Let it give us one more final pleasure: drink it
    and forget it all!

            - Richard P. Feynman, The Feynman Lectures on Physics, v. 1, p. 3-10
                (This lecture is also one of the six lectures featured in a book &
                audio edition entitled "Six Easy Pieces")

  5. Re:sometimes I feel like I was born too late by Tyger · · Score: 4, Funny

    Besides if you are 30, by the time you are 70 it will be 2076 and if you consider all the progress made from 1906 to 1946 it will be at least interesting.

    Wow, a post from the future! What's it like in 2036?

  6. Whole chemistry is based on quantum mechanics by poszi · · Score: 4, Insightful
    I'm not a neuroscientist but I work on molecular interactions and the idea is not that far fetched. In general all interactions involve quantum mechanics. Protein folding, DNA helix, it all requires dispersion which is a purely quantum-mechanical effect. I'd say the whole chemistry is immersed in quantum mechanics. Well, color can only be explained by quantum excitations, so why not smell?

    This theory is "revolutionary" because biochemists use classical simulations. Quantum mechanics is very difficult to apply to such large systems in practice but these molecules definitely are governed by quantum mechanics like all molecules.

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