SIZE-DEPENDENT TRANSITION TO HIGH-DIMENSIONAL CHAOTIC DYNAMICS IN A 2-DIMENSIONAL EXCITABLE MEDIUM

The spatiotemporal dynamics of an excitable medium with multiple spira l defects is shown to vary smoothly with system size from short-lived transients for small systems to extensive chaos for large systems. A c omparison of the Lyapunov dimension density with the average spiral de fect density suggests an average dimension per spiral defect varying b etween 3 and 7. We discuss some implications of these results for expe rimental studies of excitable media.