Prof. Raymond Goldstein of Cambridge University has ‘unlocked’ the complex curvature of ponytails. Goldstein, a professor of complex systems has published his results in this week’s Physical Review Letter. Entitled
Shape of a Ponytail and the Statistical Physics of Hair Fiber Bundles, the abstract of the paper reads;
A general continuum theory for the distribution of hairs in a bundle is developed, treating individual fibers as elastic filaments with random intrinsic curvatures. Applying this formalism to the iconic problem of the ponytail, the combined effects of bending elasticity, gravity, and orientational disorder are recast as a differential equation for the envelope of the bundle, in which the compressibility enters through an “equation of state.” From this, we identify the balance of forces in various regions of the ponytail, extract a remarkably simple equation of state from laboratory measurements of human ponytails, and relate the pressure to the measured random curvatures of individual hairs.
CBC had an interview with Prof. Goldstein that you can listen here;
The study is not a mere academic curiosity. One of the co-authors is from Unilever and for them this will go a great length in developing hair care products that will help keep that much desired shape in ponytails.