Dec 17

Reported by Brandon Keim in Wired Science, December 15, 2010.

As-yet-unexplained laws of physics keep popping up in the darnedest places, like, for example, this bed of nails.

Perfectly arrayed in horizontal rows, one would expect their pattern to break down when shaken. But as this stop-motion video shows, they lose pattern in a very orderly way.

The video was taken by T. Lynn MacDonald, a student in the lab of University of Toronto physicist Stephen Morris. His specialty is experimental nonlinear physics, investigating how and why patterns emerge in interacting particles. Whether the particles are water molecules, grains of sand, inch-long nails or stars is just a matter of scale.

Morris’ lab received plenty of attention this year, first for research on theories of icicle formation and then for a “Supernova in a Jar.” Flying under the radar was MacDonald’s as-yet-unpublished work on nails, which shows them collectively transformed in a way typically seen when heat transforms crystal to liquid.

By shaking the bed of nails, “we ‘melt’ it,” wrote Morris in an email.

The observations represent an early research stage, with fuller investigations to come. “The emergence of collective behavior is exactly the point of the experiment,” wrote Morris. The experiment also hints at a non-scientific truth, articulated by mathematician Henri Poincaré and epigraphed on Morris’ website:

“The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful,” wrote Poincaré.

Video: Melting a liquid of nails: A perfectly ordered array of  nails “metls” like a crystal turns into a liquid. Credit: by T. Lynn MacDonald & Stephen Morris, University of Toronto.

Read more in “Pattern Formation in Vertically Vibrated Nails,” by T. Lynn MacDonald. Unpublished, available online (pdf).

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