Experimental tests of granular kinetic theory: We conduct experiments to directly test granular kinetic theory in the laboratory. From snapshots of a 2D rotating layer of spheres trapped between two glass plates, we extract the velocity field using a temporal cross-correlation technique we developed for dense granular flows.  The result is shown to the left as a speed field.  We measure the local statistical properties of the grains from close-up high-speed digital photography shown in the lower left image.  We developed highly adaptable particle tracking software to extract the velocities of individual particles.  The blue and green dots are the centers of the particles in successive frames.  From this data, we calculate the histogram of the velocities (small blue dots) that shows excellent agreement with kinetic theory (solid black curve).  At moderate rotation rates three flow regimes are formed --- a dilute gas at the top, a dense gas in the middle, and an elasto-plastic solid at the bottom. In earlier work, we have confirmed that continuum equations of motion derived using kinetic theory of dense inelastic gases give quantitative results for the dilute phase. We are now exploring their applicability to the dense phase, where we may encounter viscoelastic behavior, which is not currently included in the theory.  Finally we are exploring ways of extending kinetic theory and connecting with elasto-plastic solid models to bring the entire flow regime under a unified theory.