The flux capacitor, the core component of a machine that allowed Brown to travel through time. Brown came up with the idea of the capacitor on November 5, 1955, and worked tirelessly for the next 30 years developing it into a working time machine. The capacitor, which requires 1.21 Gigawatts of electrical power to function, was first implemented in a customized DeLorean and later, or maybe earlier?, in a 19th century train.
Link
http://www.youtube.com/watch?v=N3F5SHvkERQ