This is a model of signal propagation in the form of a two-dimensional cellular automaton. A cell can be inactive or in a number of activated states. Inactive cells will stay inactive unless enough of the neighbouring cells are in an activated state. Once activated a cell will progress through all of the active states one by one. When the last active state has been reached the cell will become inactive again in the next time step.
Try different combinations of the number of states and activation threshold. When the threshold is too low the system will flicker randomly, while when it is too high all activity will die out. For intermediate thresholds signals (e.g. spiral waves) will propagate over the lattice.
The applet is currently using a 250x250 lattice. Reload the applet with a :
Above is a map of typical configurations for different combinations of threshold levels and number of states. The number of states varies along the y-axis, while the threshold level varies along the x-axis.