BS: Tech: How Does Your Hair Hang?

Subject: BS: Tech: How Does Your Hair Hang?
From: JohnInKansas
Date: 12 Feb 12 - 04:31 PM

'Rapunzel Number' helps scientists quantify ponytails

Equation settles a 500-year-old conundrum: How does your hair hang?

Reuters
2/11/2012

LONDON — British scientists say that a "Rapunzel Number" may have helped them to crack a problem that has perplexed humanity since Leonardo da Vinci pondered it 500 years ago.

Scientists from the University of Cambridge and the University of Warwick reported on Friday they had devised a "Ponytail Shape Equation" — which, when calculated using the Rapunzel Number and a measure of the curliness of hair, can be used to predict the shape of any ponytail.

Cambridge Professor Raymond Goldstein told Reuters that he and his colleagues took account of the stiffness of individual hairs, the effects of gravity and the average waviness of human hair to come up with their formula.

The Rapunzel Number provides a key ratio needed to calculate the effects of gravity on hair relative to its length.

"That determines whether the ponytail looks like a fan or whether it arcs over and becomes nearly vertical at the bottom," Goldstein said in a telephone interview.

The research also took into account how a bundle of hair is swelled by the outward pressure that arises from collisions between the component hairs.

Scientists said the work has implications for understanding the structure of materials made up of random fibers, such as wool and fur, and will have resonance with the computer graphics and animation industry, where the representation of hair has been a challenging problem.

"Our findings extend some central paradigms in statistical physics and show how they can be used to solve a problem that has puzzled scientists and artists ever since Leonardo da Vinci remarked on the fluidlike streamlines of hair in his notebooks 500 years ago," Goldstein said.

The research was conducted by Goldstein, Robin Ball from the University of Warwick and their colleagues. It will be presented to the American Physical Society in Boston on Feb. 28.

Copyright 2012 Thomson Reuters

There is a link, at the link given, where you can download your own PDF of the mathematics involved, should you be interested in calculating how your own ponytail might look if you let it be a little longer - or shorter.

Obviously, most people here (at least in BS) will want to watch for sequel studies related to how other things hang.

The burning and somewhat unsettling question for some of us will be whether the classic

        "Do your b**** hang low?"

will need to be rewritten to

        "How do your b**** hang, low?.

There may, in fact, be other "hanging things" of folkish and/or traditonal musical ilk that could benefit from more complete analysis, so continued research and reporting of this very important line of analyses will be eagerly awaited.

Surely the researchers who did this important work would be most interested in suggestions for further "hanging down" questions to explore, and consideration might be given to suggesting appropriate names for those "other" currently undetermined factors in need of definition and description.

John

Subject: RE: BS: Tech: How Does Your Hair Hang?
From: Rapparee
Date: 12 Feb 12 - 05:34 PM

Tom Dooley, mayhap?

Subject: RE: BS: Tech: How Does Your Hair Hang?
From: gnu
Date: 12 Feb 12 - 06:44 PM

I don't need an equation. I think mine would look silly.

Subject: RE: BS: Tech: How Does Your Hair Hang?
From: frogprince
Date: 12 Feb 12 - 08:00 PM

My dooley looks silly, but my wife doesn't seem to mind.

Our neices husband has done computer graphics for film including
Spiderman and Beowulf. His latest credit that we know of is for "hair and fabric".