English: This example illustrates the process of gaseous diffusion. The colored blocks represent molecules that are experiencing Brownian motion. Over time the two colors will be approximately evenly distributed between the top and bottom half.

The image is an animated output of a CAGE simulation. The display is a two-dimensional black grid on a white background. A purple line is drawn horizontally spitting the grid in half, leaving the right one-quarter of the separation open. The simulation begins with about 20 light purple squares randomly placed above the delineation and the same number of green squares below. The squares are immediately set in motion and bouncing off any border it makes contact with. Squares are able to pass from top-to-bottom and bottom-to-top through the gap left on the right. Eventually the light-purple and green squares are equally distributed on the top and bottom. The simulation

simply continues indefinitely, resetting itself periodically.