Sense of Smell Due To Quantum Mechanics?

The prevailng theory is that smell is chemical -- molecules have different shapes that fit into smell-receptors, triggering them if the stimulus "key" fits the receptor "key."

But a new theory suggests smell is largely atomic. Or subatomic, really.

But Turin argued that smell doesn't seem to fit this picture very well. 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 — to animals, if not necessarily to humans — simply because they contain different isotopes (atoms that are chemically identical but have a different mass).

Turin's explanation for these smelly facts invokes the idea that the smell signal in olfactory receptor proteins is triggered not by an odour molecule's shape, but by its vibrations, which can enourage an electron to jump between two parts of the receptor in a quantum-mechanical process called tunnelling. This electron movement could initiate the smell signal being sent to the brain.

This would explain why isotopes can smell different: their vibration frequencies are changed if the atoms are heavier. Turin's mechanism, says Marshall Stoneham of the UCL team, is more like swipe-card identification than a key fitting a lock.

New euphemism for flatulance: Splitting atoms... with my ass.

posted by Ace at 01:22 PM

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