The concept of using a watch or any device from the movie "Back to the Future" to travel back in time is purely fictional and not based on any real scientific principles or technologies. The watch featured in the movie, called the DeLorean time machine, is a work of science fiction.
In the "Back to the Future" trilogy, the DeLorean time machine equipped with a flux capacitor and a plutonium-powered nuclear reactor allows for time travel when certain conditions are met. However, it is important to note that this is a fictional creation for the purpose of storytelling and entertainment.
As of now, time travel to the past remains a speculative and hypothetical concept in the realm of science fiction. There are no known devices or methods that have been scientifically validated for traveling back in time. The scientific community continues to explore and study the laws of physics, but time travel is not currently considered a realistic possibility within our current understanding of the universe.