Current research on thermodynamics of jamming: Simulations and experiments are being performed to investigate the statistical mechanics of jammed particulate matter.
(a) Simulations of grains (100 microns) interacting via Hertz-Mindlin contact forces . A slow shear flow, indicated by the arrows, is applied to the jammed system. We follow the tracer particle trajectories to obtain the diffusivity. An external force $F$ is then applied to the tracers in response to which we measure the particle mobility. These dynamical measurements yield an “effective temperature” obtained from an Einstein relation which is indeed very close to that obtained by a flat average over the ensemble of jammed configurations as proposed by Edwards and coworkers .
(b) A novel fluorescence mechanism using confocal microscopy is providing new insight into the microstructure and the mechanics of jammed matter . The suitable model system is an emulsion comprised of oil droplets of approximately 3 microns dispersed in a refractive index matching solution. The system forms a random close packed structure by creaming or centrifugation giving rise to a force network. Based on the bright contact areas, the interdroplet forces can be extracted. The resulting micromechanics is being used to develop statistical theories of jammed materials.
 H. A. Makse and J. Kurchan, “Testing the Thermodynamic Approach to Granular Matter with a Numerical Model of a Decisive Experiment”, Nature 415, 614-617 (2002).
 Edwards, S. F. The role of entropy in the specification of a powder, in Granular matter: an interdisciplinary approach, (ed Mehta, A.) 121-140 (Springer-Verlag, New York, 1994)
 J. Brujic, S. F. Edwards, I. Hopkinson, and H. A. Makse, “Measuring the distribution of interdroplet forces in a compressed emulsion system”, Physica A 327, 201-212 (2003).