In the course of an exciting experiment, the wizards of Discworld have accidentally created a new universe. Within this universe is a planet that they name Roundworld. Roundworld is, of course, Earth, and the universe is our own. As the wizards watch their creation grow, Terry Pratchett and acclaimed science writers Ian Stewart and Jack Cohen use Discworld to examine science from the outside. Interwoven with the Pratchett's original story are entertaining, enlightening chapters which explain key scientific principles such as the Big Bang theory and the evolution of life on earth, as well as great moments in the history of science.