Physics: A Fine-Grained Look at Forces in Sand
James Glanz
KANSAS CITY, MISSOURI--Next time you stand on a sandy beach, you may be intrigued to know that some surprising physics is taking place right under your feet. At an American Physical Society meeting here last month, researchers described a set of experiments that have begun to piece together just how weight gets divvied up and passed downward in granular materials like sand and beads. It turns out that the forces are not distributed evenly among the grains; instead, the weight gets transmitted downward from grain to grain in jagged "force chains."