Quantum theory of smell causes a new stink

Jacob Aron, reporter

The first evidence from tests on people that our ability to distinguish between different scents involves quantum mechanics has reopened a long-standing debate.

Most researchers think a molecule's odour is determined by its shape, with smells triggered when the molecule enters a suitably shaped receptor in the nose, like a key entering a lock. Luca Turin of the Fleming Biomedical Research Sciences Centre in Vari, Greece disagrees, because some molecules with different shapes have similar smells.

In 1996 he proposed that a smell receptor would only fire when a molecule vibrated at the right frequency. These vibrations provide enough energy to trigger a quantum tunnelling effect, causing an electron to pass across the receptor and trigger a smell.

One way to test the theory is replacing the hydrogen atoms in a molecule with deuterium, a hydrogen isotope with a nucleus of a neutron and a proton, rather than just a proton. The shape of the molecule barely changes, but the added neutrons alter the frequency of its vibrations. Turin's previous experiments have shown fruit flies can distinguish between the original and altered versions of acetophenone, a common perfume ingredient, but similar tests on humans had failed.

Now Turin and colleagues have attempted the same experiment with larger molecules and discovered that?humans can detect a significant difference in odour. They put this down to an increased number of carbon-hydrogen bonds in the larger molecules, as these bonds maybe responsible for the vibrational effect.?

Researchers supporting the shape model of smell remain unconvinced though, with?Tim Jacob?of Cardiff University, UK telling the?BBC?that the new results were "supportive but not conclusive".

Meanwhile,?Ilia Solov'yov?of the University of Illinois at Urbana-Champaign,?told Chemistry World?he was "not convinced" the results prove humans could smell the difference between the two types of molecules.

More broadly, there is increased interest in the?quantum biology, including recent evidence that?birds may use quantum mechanics to navigate.

Source: http://feeds.newscientist.com/c/749/f/10897/s/27fc2bb4/l/0L0Snewscientist0N0Cblogs0Cshortsharpscience0C20A130C0A10Cquantum0Esmell0Etheory0Ecauses0Ene0Bhtml0Dcmpid0FRSS0QNSNS0Q20A120EGLOBAL0Qonline0Enews/story01.htm

wargames blake griffin dunk florida primary full force odd fellows eli whitney blake griffin dunk on kendrick perkins