The depiction of time travel in the movie "Back to the Future" is primarily a work of fiction and should not be taken as a realistic representation of time travel as currently understood in scientific terms. While the movie presents an entertaining and imaginative portrayal of traveling through time, it involves several concepts and ideas that are not supported by our current scientific knowledge.
Here are a few reasons why the movie's portrayal of time travel differs from scientific understanding:
Time machine design: In the movie, the time machine is depicted as a DeLorean car modified with a flux capacitor. The idea of using a vehicle as a time machine is purely fictional and not rooted in any scientific theory.
Causal loops and altering the past: "Back to the Future" introduces the concept of altering the past and creating causal loops. This means that changes made in the past have immediate and direct effects on the present and future. However, in scientific discussions of time travel, there is a general consensus that the possibility of altering the past in a way that creates paradoxes is highly unlikely.
Multiple timelines and parallel universes: The movie suggests that changes in the past create alternate timelines and parallel universes, which coexist with the original timeline. While the idea of multiple timelines or parallel universes is explored in theoretical physics, the specific mechanisms and implications portrayed in the movie are not in line with current scientific theories.
Time travel without the Grandfather Paradox: The Grandfather Paradox refers to the hypothetical situation where a time traveler goes back in time and does something that prevents their own existence, like killing their own grandfather. In "Back to the Future," actions in the past do not have immediate and catastrophic consequences on the time traveler's existence. However, resolving the Grandfather Paradox remains a significant challenge in any scientific discussion of time travel.
In summary, while "Back to the Future" provides an entertaining fictional take on time travel, its portrayal deviates from current scientific understanding. Time travel as depicted in the movie involves many speculative concepts and fictional devices that are not supported by scientific evidence or theories.