This image is a real photograph, it was not generated using a computer. This photograph is a long exposure of 2 LEDs, each attached to the end of each pendulum on a double pendulum. The double pendulum shows some very interesting behavior for such a simple physical system.
See http://en.wikipedia.org/wiki/Double_pendulum for more information on the device used to create this image.
Taken with a Canon 550D and 18-55 mm lens.