There may be times when you're be tempted to think that science has a lock on who we are and how we work. But just consider that some of the most basic things that make us human, that play important roles in our lives, remain rather mysterious. We don't really know why we laugh, cry, dream, sleep — or how we smell the scents around us.
Smell is a loaded matter. Gets right to the heart of things, often things that we don't generally talk about in "polite society" — which might, for that reason, be called "smell-blind" society. (Curious, too, that we don't have a word for "unable to smell." Deaf, blind, dumb — and most of us most of the time.) Of course, in some areas we go on about smells a great deal. Wine's "bouquet" (not "smell," notice) and the scent (not "odour" and certainly not "stink") of perfume, come to mind.
But how does smell, scent, odour, stink come literally to my mind? What's the science of smell?
Turns out it's not a settled matter. The received notion, as I understand it, is that molecules of a particular oderant have a unique shape that will latch on to some of the five or six million receptors in our olfactory area and thus trigger signals that cause the brain to register a particular smell. In the last few years, however, a different and quite controversial theory has arisen to challenge this view. The new theory claims that it is the vibrations of the molecules at the atomic level that "creates" smell. But how we could detect something so subtle, shall we say, is not entirely clear.
The leading proponent of this vibrational theory is biologist-turned-parfumier Luca Turin. He's a truly engaging lecturer, so I'll let him explain the theory to you and give you the rather compelling reasons why the molecular shape model fails to explain the evidence.