"Back to the Future" is a 1985 American science-fiction adventure comedy film. Doc Brown is a scientist that helps the main character travel back and forth in time.

Einstein was Doc Brown's pet sheepdog in 1985, and later pet to the Brown family. His age in 1985 was unknown, although he was fully grown and most likely "middle aged" for a dog. He was the latest of many Doc's pet dogs named after famous scientists, in this case Albert Einstein. It was, therefore, quite fitting that he became the world's first time traveler.

Doc ended being sent back to 1885 when the DeLorean was struck by lightning in 1955. In a letter to Marty, who was trapped in 1955, Doc told Marty he was perfectly happy living and working as a blacksmith in the Old West, and asked his friend to give Einstein a good home once he returned to 1985. However, having seen Doc's tombstone in the Boot Hill Cemetery, Marty headed back to 1885 to save Doc from certain death at the hands of Buford Tannen instead of going back to 1985.

After Marty left Doc behind in 1885, Doc (who had spent ten years of his life in the late 19th century) returned to 1985 with his wife Clara and sons Jules and Verne. They picked up Einstein from Doc's lab, and the dog became the family pet. Although it had been ten years since Doc saw Einstein, it had only been about 10 hours since Einstein last saw Doc. Einstein was with the family right at the end when they departed in the time machine for times unknown.

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