It was a misty November morning in 1955 as Dr. Emmitt Brown sat contemplating the image of Sir Isaac Newton that he had just had framed. He wasn't sure exactly where to hang it in his home. He already had ones of Copernicus, Galileo, Occam, and Pascal hanging in his den. A large engraving of Newton already hung over his California Craftsman fireplace. He decided that he would move one of his 75 clocks and hang the picture in that place instead. Too fond of reading in the bathroom and losing hours of productivity, he decided to hang it in the bathroom. Aesthetically, it looked better higher up than he could stand, but since he didn't have a stool anywhere nearby, he elected to stand on the toilet seat. The porcelain was wet and he slipped and hit his head--knocking himself unconscious. When he came to, he had a revelation, a picture, picture in his head, a picture of this:
THE FLUX CAPACITOR, which is what makes time travel possible.
XENOPHOBIC GRINGO REMINDS YOU: Never forget that time travel first happened because of Muslim Terrorists! Who do ya think? The Libyans!