Colloquium on October 11, 2010

Mehran Kardar
Massachusetts Institute of Technology

Manipulating Fluctuation-Induced Forces

 In 1948 Casimir predicted an attractive force between (ideal) metal plates due to quantum fluctuations of the electromagnetic field. Critical fluctuations in binary mixtures, and thermal fluctuations in superfluids, were also predicted to give rise to qualitatively similar forces. In the past decade, a remarkable set of high precision experiments have confirmed many of these theoretical predictions, and embarked on manipulating fluctuation-induced forces for practical applications. The theoretical challenge is now to determine how forces and torques depend on material properties and geometry of the objects. A scattering formalism provides a new perspective that has enabled computation of forces for a variety of new shapes, including sharp edges and tips. A generalization of Earnshaw's theorem, based on this approach, constrains repulsion from Casimir forces.