Background Music: *"Espaces urbains" ("Prelude to Metropolis") is a digital remix of an electronic organ piece improvised by Joseph Dillon Ford in the late 1970s.

The background in the above animation, attributed to Arun Kulshreshtha, is a "color-enhanced version of an aerial photograph of stratocumulus perlucidus clouds taken from the rear seat of a Northwest Airlines Airbus A320 flying over the midwestern United States, en route from Los Angeles, CA to Minneapolis/St. Paul, MN." The original image may be viewed at http://en.wikipedia.org/wiki/File:Above_the_Clouds.jpg. It is licensed under the Creative Commons Attribution 3.0 United States license.