[lit-ideas] Re: For Those Who Were Worried...
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- To: lit-ideas@xxxxxxxxxxxxx
- Date: Tue, 14 Feb 2012 09:47:50 +0100
On 14-Feb-12, at 6:00 AM, David Ritchie wrote:
...the ponytail problem has been solved:
http://www.bbc.co.uk/news/science-environment-17012795
"'It's a remarkably simple equation,' explained Prof Raymond
Goldstein ..."
I was wondering just how 'simple' so I searched - and found
The Shape of a Ponytail and the Statistical Physics of Hair Fiber
Bundles
- Raymond E. Goldstein, Patrick B. Warren, and Robin C. Ball
[Abstract] 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.
http://www.damtp.cam.ac.uk/user/gold/pdfs/ponytail.pdf
It is reported at the end of the paper that the work "was supported in
part by the Schlumberger Chair Fund."
Chris Bruce,
wondering (after perusing Goldstein, Warren and Ball's paper)
a) about the definition of the term 'remarkably simple' as used there,
b) just who it is (outside of the Steven Seagal fan club, perhaps)
who finds the problem of the ponytail 'iconic', and
c) if I'd find a Schlumberger Chair down at the local hair salon, in
Kiel, Germany ------------------------------------------------------------------
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