The Physics Of Ponytails

I kid you not! They even came up with something called the "Rapunzel Number"!

It turns out that there is an important-enough research being done on the physics of ponytails that it warrants a publication in the Physical Review Letters, no less!

He and two other physicists have been trying to determine whether the shape of a ponytail can be deduced from the properties of a single hair. After all, a head with 100,000 strands is a complex physical system, as anyone with a copious coiffure can attest. 

And it turns out that there is a simple theory. The crucial characteristics are elasticity, density and curliness, which essentially tell how springy a piece of hair is, plus the length of the ponytail. The researchers came up with a simple formula that describes the ponytail shape when the hair is bundled together.

They called it the Rapunzel number. “We couldn’t resist,” Dr. Goldstein said. 

Oh dear!

I'll try to find the exact reference to this one when it appears and post it here. I wish they explain why this is important and what other implications this involved. Maybe it's written in the actual paper. The only thing I can find in the news article is the sentence "...  Dr. Goldstein said the findings could also be applied to bundles of other long filaments, including fiberglass and wool...", which doesn't say much.

Another news report on this story mention quite a bit more, but it is still unclear what properties actually that is so important.

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 fluid-like streamlines of hair in his notebooks 500 years ago," Goldstein said.

So maybe this won't be nominated for an Ig Nobel after all! :)

Edit: the Ponytail physics is getting a Synopsis coverage! Click that link for the exact reference.

Zz.