This composite image contrasts numerical solutions for an electric field in two dielectric cavities. The elliptical shape (top half) supports regular, non-chaotic motion of light rays, whereas motion in a stadium shape (bottom half) is necessarily chaotic. The colors represent field intensity. The dramatically different patterns illustrate that quantizing chaotic systems is fundamentally different from quantizing non-chaotic systems, as was first appreciated by Albert Einstein in 1917. © Physics Today, August 2005.

Submitted by A. Douglas Stone