The flux capacitor is a device that can be fitted into something to allow it to travel in time. To function properly it needs 1.21 gigawatts of electricity, which is roughly the same as is given off when being struck by lightening but the energy can also be produced by weapons grade plutonium.
It was invented by Dr. Emmett Brown on November 5 1955. He was standing on a toilet hanging a clock and slipped and hit his head on the sink. When he came to, the idea for the flux capacitor just came to him.