Ray Goldstein Shares 2012 Ig Nobel Prize for Physics
A team of researchers including Professor Ray Goldstein of DAMTP has been awarded the 2012 Ig Nobel Prize in Physics for their work on the physics of hair. These prizes, now in their 22nd year, are awarded for "achievements that first make people laugh, and then make them think. The prizes are intended to celebrate the unusual, honor the imaginative — and spur people's interest in science, medicine, and technology". Sharing the prize with Goldstein were Dr Patrick Warren of Unilever Research UK, Professor Robin Ball, Head of Physics at the University of Warwick, and Professor Joseph Keller, emeritus professor of mathematics at Stanford University.
The four were honoured for ``calculating the balance of forces the shape and move the hair in a human ponytail". The paper by Goldstein, Warren and Ball, ``Shape of a Ponytail and the Statistical Physics of Hair Fiber Bundles", published in Physical Review Letters in February 2012, developed a density functional theory of hair bundles in which the effects of the random curvatures of hair fibres are seen through an internal pressure that swells a bundle from the shape determined otherwise by the balance of elastic and gravitational forces. Measurements of the spectrum of curvatures of many individual hairs in standardized commercial hair `switches` allowed an interpretation of the equation of state of hair determined from digitized images of the shapes of ponytails. The result was an extremely simple Hookean equation of state in which the effective spring constant is related to the filament stiffness and mean squared intrinsic curvature. That result, in turn, has interesting parallels with the statistical physics of polymeric systems.
Keller's independent work was aimed at understanding the swing of the ponytail of a jogger whose head bobs up and down. Through a progression of mathematical models, he calculated the parametric resonance by which the vertical forcing leads to horizontal swinging.
The four scientists received their prize at a festive and humorous ceremony at Harvard University on September 20th.