Stephen Wolfram
An arrangement of mirrors set up to exhibit randomness arising from sensitive dependence on initial conditions. The initial condition for the system is specified by the position of the incoming light ray in the gray region at the top of each picture. Whether the light ray goes to the left or to the right at each step is then determined by successive digits in the base 2 representation for the number that gives the initial condition. The heart of the system is the "amplifier" shown on the left which uses a pair of parabolic mirrors to double the displacement of each incoming ray. The initial condition used here is pi/4, which has digit sequence 0.1100100100001111111.

[From A New Kind of Science, page 311.]

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