Sense of Smell Could Depend on Quantum Mechanics

Nature is reporting the results of a study (abstract) related to the involvement of quantum mechanics in the process of smelling. The theory suggests that smelling odor molecules involves sensing their molecular vibrations and was first proposed by biophysicist Luca Turin in the mid-1990s. Turin explained olfactory function in terms of a molecule's vibrations, which can encourage an electron to jump between two parts of the receptor in a quantum-mechanical process called tunnelling. Calculations by researchers at University College London have now shown the theory to make sense in terms of the physics involved. Whether or not it is biologically accurate, however, has yet to be determined.

The prevalent scientific understanding of the sense of smell involves olfactory receptors in the nose detecting the shape of incoming molecules, similar to the process underlying other biological detection systems such as how some parts of the immune system recognize invaders and how the tongue recognizes some tastes, for example.

Turin, however, recognized inconsistencies in this theory. "Molecules that look almost identical can smell very different — such as alcohols, which smell like spirits, and thiols, which smell like rotten eggs. And molecules with very different structures can smell similar. Most strikingly, some molecules can smell different ... simply because they contain different isotopes."

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