BBC2 Horizon: How long is a piece of string?
Publication date: Nov 13, 2009 9:46:20 AM
Prof. Marshall Stoneham is interviewed in this BBC2 Horizon documentary:
Molecules you can smell are small - they must be volatile. Yet somehow, the receptors in your nose must send different signals to the brain so it can tell them apart
Most biologists think receptors work like a lock and key - molecular shape is all that matters. But molecules with the same shape smell different. And molecules with very different shapes smell the same.
In the 1990s, Luca Turin (then UCL) took the old idea that molecular vibration frequencies were critical, and he proposed the QUANTUM idea that the nose used inelastic tunnelling.
Derek Roberts, then UCL Provost, used to get small groups in his office for half an hour to discuss interesting ideas he had heard. I was there when Luca described his theory. I didn't believe it either, but it was interesting so thought I should prove him wrong. I gradually decided it might be right.
In 2004, Jenny Brookes and Filio Hartoutsiou came to UCL as MSc students.
You can tackle way out projects for an MSc, and they, Andrew Horsfield (still LCN, but now Imperial) and I asked "Are there any physics based reasons why this mechanism can't work?" The simple answer is that the method seemed to be very robust - no problems, and basic processes in line with what was known. We published this (Jennifer C Brookes, Filio Hartoutsiou, A P Horsfield and A M Stoneham 2007 Phys Rev Letters 98 038101 Can humans recognize odor by phonon assisted tunneling?) and it was identified as of special interest by the PRL editors, and was commented on in New Scientist, by Philip Ball in Nature (online), Scientific American, New Scientist, and in various newspapers.
Obviously, we took this further - Jenny in her PhD (and she subsequently won a Wellcome personal Fellowship, and is now in MIT) discovered a new rule about chiral molecules and whether left- and right-handed molecules smell the same. We are also taking this forward experimentally, and Simon Gane (the one who sticks the probe up Alan davies's nose in the programme) is working on isotope experiments when he can escape his responsibilities as a fully qualified doctor.
Marshall Stoneham
The documentary was shown on BBC2, Thursday 12th Nov 9pm 2009, and can be viewed on the BBC i-player at http://www.bbc.co.uk/programmes/b00p1fpc
