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