Is Smell Vibrational?

Photo via flickr by Ben Scicluna

Quantum vibration theory of smell is gaining credibility. Physicist Marshall Stoneham at the University College London is putting scientist Luca Turin’s controversial theory to the test. In Turin’s model, receptors are cued by the vibrational frequency of the odor molecule. This differs strongly from the leading theory, which supposes that the shape of the odor molecule allows it to fit like a key into the appropriate lock-like receptor. But while the shape theory is the one most accepted by scientists, it has not been proven. Shape still has a role in Turin’s model, however, being part of what determines the molecule’s overall vibrational frequency. Using quantum mechanics, says Turin’s model, an electron “tunnels” through the odor molecule, distorting its electrical field. Stoneham’s study supposed that an odor molecule sits between an electron donor and an electron receptor, while the electron “tunnels” its way to the receptor, thus activating it. The detailed structure of the receptors is unknown, but the calculations made by Stoneham and his colleagues came out favoring Turin’s mechanism.

via Air Sense

In a conversation with Sputnik Observatory, biophysicist Luca Turin explains the theory and history of smell as vibration:

Q: Please explain your theory that smell is vibrational.

It’s actually not my idea, I wish I could say it was, but it was first proposed by a remarkable man named Malcolm Dyson in the ‘30s. He was a very brilliant chemist, and among other things he is responsible for a lot of the notation that we describe molecules with. He devised a way of naming molecules, but that was only a side activity of his. His main thing was just straight-up chemistry. But he was also interested in how we smell, and he was the first guy to suggest that maybe what we smell in molecules is their vibrations. In 1929 and in the ‘30s when he put it forward it was politely received, I would say, rather than enthusiastically. And nothing very much happened. The idea just died a death and was revised in the ‘60s by a very remarkable man called Robert Wright, and then died again in the ‘70s.

My version of it is new and improved and it is the third incarnation of this idea. The biggest difficulty was in imagining a way in which proteins, normal components of living things, could do the job. And that’s what I have done. So mechanism was everything, and that’s my contribution to the story – figuring out a way in which organisms could detect the vibrations of molecules.

Q: And how do organisms detect vibrations of molecules?

Well, you see, the wrong assumption that was always made was that there was only one way to do spectroscopy and that was optical – you shine light of a particular frequency, infrared light of a particular frequency, at a molecule, and if the molecule absorbs the light it means the molecule has that particular frequency of vibration. And so optical equipment and infrared is hard to imagine in biology, people just thought it was rubbish. But it turns out there is another way of doing spectroscopy which is electronic. Essentially, solid-state device. And it lends itself very nicely to being a tiny size of a protein. It’s an intrinsically nanotechnological thing, this electronic spectroscopy. And that was discovered in the ‘60s, and the people who discovered it, strangely enough, John Lamb and Bob Jacklovich at Ford Motor Company, the first thing that came to their mind, and I must say that I admire them for that, was that it had to do with smell.

They discovered this electronic way of doing spectroscopy and they thought, “Maybe this is how we smell?” And what do they do? They went down the corridor and asked a chemist, “What do you think?” And the guy said, “Nah, it’s all molecular shape.” And they gave up. When they told me that, I was stunned. Because if they had only realized that Robert Wright, at the same time, was proposing that smell was due to vibration, all it would have taken was one phone call from Detroit to Vancouver and the whole field would have been completely different.

Hearing is clearly vibration. Hearing is vibration, as it says in all the ads for speakers, from 20 to 20,000 Hz. Actually, at my age 16,000 would be pushing it. And, of course, color vision is vibrations of light. The fact that smell is vibration as well, I should say, is attractive if you have a philosophical frame of mind. “Oh, it’s all wonderful harmony of nature, everything is vibration.” I personally think that it could be attractive and still be wrong. So that’s not an argument in its favor. Ultimately, it could be that it could be something else. Nature does what it likes and doesn’t care about whether Goethe would like it. But how’s it changing the industry? The answer is, “It is going to.”

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