The packing of hard particles: From granular media, to metallic glasses, to protein cores.

The packing of hard particles has fascinated scientists for centuries: from Kepler's conjecture about dense sphere packings, to Hales' experiments on the respiration ability of peas, to Bernal's studies of ball bearings that describe liquid structure.  In this talk, I will describe theoretical and computational studies that employ hard-particle models (with purely repulsive contact interactions) to describe: 1) the variation of the number of interparticle contacts in packings of frictional spheres, 2) the glass-forming ability of bulk metallic glasses (BMGs), and 3) the side chain conformations of hydrophobic residues in protein cores. While it may be obvious that hard-particle models are able to quantitatively describe static packings of macroscopic grains, it may be a surprise that hard-particle models can be used to design new BMGs and can be employed to predict side chain conformations in protein cores.  I will show that in these three disparate systems the hard-particle model provides key physical insights that are obscured with more complex models.