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Sense of Smell Tied To Quantum Physics?
Posted by
kdawson
on Mon Dec 11, 2006 05:28 PM
from the sniffing-out-a-theory dept.
from the sniffing-out-a-theory dept.
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."
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Raised eyebrows... (Score:5, Informative)
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.
Re:Raised eyebrows... (Score:4, Interesting)
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Re:Raised eyebrows... (Score:4, Funny)
Sure! It means that the smeller has an effect on the smelled! It also explains why Schroedinger never took into account the SMELL of that both dead and alive cat...
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Re: (Score:3, Funny)
Unfortunately the Uncertainty Principle states that you can't simultaneously know what a fart smells like and where it came from. That explains why your own farts never smell as bad.
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Re:Raised eyebrows... (Score:4, Insightful)
You're basically right, though: Major oscillations between groups of neurons or anything like that is something radically different than this, and this theory doesn't make that any more likely. Even in that case, there is no reason to scream "quantum" (as in: impossible to handle with good old Newtonian physics/statistical chemistry/thermodynamics), as the main effects should be the varying electrical field, which we can easily measure with EEG electrodes. Some degree of leakage/overhearing is known, but I've no idea if anyone has found that as crucial to proper function, rather than a noise effect that's generally filtered out.
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Smelloscope (Score:3, Funny)
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Except that gases that are meaningfully different to us humans and other forms of life are different on a much greater than quantum scale. And the range of those gases that there is evolutionary pressure to detect is limited to those that appear with enough regularity in the terran biosphere to
Re:Raised eyebrows... (Score:4, Insightful)
You are right about the established body of literature that already explains much of the sense of smell. However I think it's worth keeping in mind that the two explanations are not mutually exclusive. It sounds like even the scientists in question are treating it like this is an either/or situation, but there's nothing impossible about smell involving a combination of shape-specific molecular recognition and electron-tunneling-specific molecular recognition. Perhaps some shape is the general measurement and then electronic effects provide secondary information.
In any case, it sounds like it is worth some further investigation. There are still many unanswered questions. However, like you, I won't be investing just yet!
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Re: (Score:3, Interesting)
Actually, there seems to be quite a lot of noise in our brain. [zdnet.com]
Re:Raised eyebrows... (Score:5, Insightful)
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.
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Re:Raised eyebrows... (Score:4, Interesting)
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Re: (Score:3, Informative)
The notion that things with similar structures having different smells - well, things with different structures often have different chemistries. Often a slight change in structure has significant effect on shape, size, polarity, electronegativity, etc, and these things can have enormous impacts on the ability of an odorant to fit correctly with a G-coupled protein receptor, which are the proteins responsible for olfaction.
The notion that things with different structures smelling the same is irrelevant -
Re:Raised eyebrows... (Score:5, Informative)
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.
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Re:Raised eyebrows... (Score:5, Interesting)
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Re:Raised eyebrows... (Score:4, Informative)
A PSYCHOPHYSICAL TEST OF THE VIBRATION THEORY OF OLFACTION
Keller A., Vosshall L.B. Laboratory of Neurogenetics and Behavior,
Rockefeller University, New York, NY
At present no satisfactory theory exists to explain why a given
molecule has a particular smell. A recent book about the physiologist
Luca Turin has generated new interest in the theory that the smell of a
molecule is determined by its intramolecular vibrations rather than by
its shape. We present the first psychophysical experiments in humans
that test key predictions of this theory. The results suggest that
molecular vibrations alone cannot explain the perceived smell of a
chemical. Specifically, we have found that: (i) in a component
identification task no vanilla odor character was detected in the mixture
of benzaldehyde and guaiacol (ii) odor similarity ratings did not reveal
that even and odd numbered aldehydes form two odor classes and (iii)
naive subjects who could easily discriminate the smell of two molecules
that differ in shape but not in molecular vibration failed to discriminate
two molecules with similar shape but different molecular vibrations in
three different experimental paradigms (similarity rating, duo-trio test,
triangle test). Taken together our findings are consistent with the idea
that the smell of a molecule is determined by its shape but we found no
evidence that the smell of a molecule is influenced by its vibrational
properties.
They subsequently published their findings in Nature Neuroscience.
Keller A, Vosshall LB. A psychophysical test of the vibration theory of olfaction. Nat Neurosci. 2004 Apr;7(4):337-8.
At present, no satisfactory theory exists to explain how a given molecule results in the perception of a particular smell. One theory is that olfactory sensory neurons detect intramolecular vibrations of the odorous molecule. We used psychophysical methods in humans to test this vibration theory of olfaction and found no evidence to support it.
The short version is that the data do not support Luca Turin's speculation.
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Whole chemistry is based on quantum mechanics (Score:5, Insightful)
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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Been rooting for this guy! (Score:5, Insightful)
For proof that success is the best revenge, just check out the company's product list [flexitral.com]. 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.
Re: (Score:3, Insightful)
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.
I guess I'd be impressed if he actually did science and came up with an experiment or series of experiments that showed that his theory was correct, and the old theory is incorrect.
Since we presumably don't have any idea how his scent cre
Re:Been rooting for this guy! (Score:4, Informative)
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Hmmm (Score:5, Funny)
So... Umm... (Score:3, Funny)
Or if it does smell stinky, I can be certain in another universe it smells like roses?
sometimes I feel like I was born too late (Score:2, Insightful)
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Well if you believe in Quantum Immortality [wikipedia.org] then chances are you can only exist in a universe that such events happen in which scientific progress lets you exist forever.
As were all thos
Re:sometimes I feel like I was born too late (Score:5, Funny)
Wow, a post from the future! What's it like in 2036?
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Can I be the first to say... (Score:2, Funny)
tied to quantum physics (Score:3, Insightful)
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Well, quantum physics is just a model. We'll probably find out later on down the road that we're all just figments of the highly detailed imagination of a resident of Snarfblatt IV and our "universe" will cease to an end one day as he is run over by a passing Warfleblorter.
*shakes his head* This is why people need to take Warfleblorting safety seriously.
Re:tied to quantum physics (Score:5, Interesting)
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")
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Ultimately, yes, but not immediately (Score:2)
The usual explanation for smell is the lock-and-key hypothesis: a specific receptor fits a molecule of a specific shape. It's similar to (and in fact related to) the immune response. QM is involved, but only in the way the molecules fold and interact, so the QM is all wrapped up by plain old chemistry.
This explanation invokes QM more directly, in a way that can't be explained by plain old chemistry. It co
Re: (Score:2)
You'll get a Nobel prize and a place in history for telling us exactly how.
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Doing quantum physics... (Score:2)
That's nothing to sniff at.
That's makes farting sense... (Score:2)
That would explain why I could evacuate a room about 30 seconds before the smell of one of my roommate's horrendous "floorboards" hit everyone else in the room. The bewildered expression on everyone's face when I ran out the room but before they got hit was priceless.
Shouldn't that be... (Score:2, Offtopic)
Okay, let's get this out of the way.... (Score:2)
I'm here are week folks....
Busted webpage? (Score:2)
Go to http://www.nature.com/news/2006/061204/pf/061204-
Credit to Richard Lederer (Score:2)
His scents sense makes cents.
Penrose and Quantum Consciousness (Score:2)
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Slow down there buddy (Score:3, Insightful)
Hold on just a minute. You are making quite a leap there, while acting as if you were just stating the obvious.
Unless you can do something along the lines of:
Why quantum? (Score:2)
Can't just be vibrational tunneling (Score:2)
I believe it (Score:2)
What about Axel and Buck theory? (Score:3, Informative)
Richard Axel and Linda Buck received their Nobel Prize in 2004 for Physiology or Medicine for "for their discoveries of odorant receptors and the organization of the olfactory system". Note that this is not *only* for the discovery of the receptors, but also for the *way they work*. There are hundreds of receptors in mammals (almost 1,000 in mice, about 330 in humans) that have different selectivities for different odorant molecules and act combinatorially, that is, that the signal perceived by the brain is the result of the combination of receptors activated by the odorant. Given the large number of receptors, and that any number can be activated by an odorant, the variety of smells is huge, and on the other hand the promiscuity of the receptors allows for a chance of 2 dissimilar molecules having the same smell...
Some literature I suggest for someone interested:
- Nobel Prize illustrated presentation: http://nobelprize.org/nobel_prizes/medicine/laure
(see also the Nobel Lectures therein)
- Unpredictability of smell: Sell, C. S. Angew. Chem., Int. Ed. 2006, 45, 6254-6261.
I really think that the system of smell is already quite strongly explained by this theory, that also follows the classical binding+activation of receptors that drives traditional biochemistry and drug design.
I'm still surprised that some theoretical chemist/physicist didn't do QM calculations to prove the tunneling, and publish it in a leading peer-reviewed journal, if the theory is so sound...
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And it's gotta be comprehensible to the layman or it'll never get past an editor.
Why don't you read the original paper instead of dismissing the research based on account filtered through the lay media?
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Electrons, photons, and protons are all merely models to explain in tangible terms what the **** is going on down there, so I become skeptical when these terms are utilized to explain/demonstrate quantum mechanics. We know how to use electricity, buy it, sell it, how to protect our kids from it, yet we really don't know what it is.
I think you're making the classic mistake of, "The math is hard and unlike other math I've seen before, therefore QM is strange and mysterious." It should come as no surprise
Re:Quantum Chemistry (Score:4, Insightful)
Um, okay, we don't know everything about these particles, but all of those things are real things very much like we describe them -- we can count electrons, photons, and protons, and in the latter case we know they are comprised of smaller things called "quarks" that when combined correctly behave very much like the little ball we call the "proton". That's as real as anything. Quantum mechanics describes the behavior of electrons, so I'm confused as to why you would be skeptical that electrons are used to explain quantum mechanics. The topics are rather intricately linked.
I'm quite certain that there are layers upon layers beyond what we know, but at this time we don't know of any way to go deeper than the electron. Hence you're basically asking for something to be described in terms of knowledge that doesn't exist yet, which is impossible.
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