The Ars guide to time travel in the movies

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Since antiquity, humans have envisioned various means of time travel into the future or the past. The concept has since become a staple of modern science fiction. In particular, the number of films that make use of time travel has increased significantly over the decades, while the real-world science has evolved right alongside them, moving from simple Newtonian mechanics and general relativity to quantum mechanics and the notion of a multiverse or more exotic alternatives like string theory.

But not all time-travel movies are created equal. Some make for fantastic entertainment but the time travel makes no scientific or logical sense, while others might err in the opposite direction, sacrificing good storytelling in the interests of technical accuracy. What we really need is a handy guide to help us navigate this increasingly crowded field to ensure we get the best of both worlds, so to speak. The Ars Guide to Time Travel in the Movies is here to help us all make better, more informed decisions when it comes to choosing our time travel movie fare.

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This is not meant to be an exhaustive list; rather, we selected films that represented many diverse approaches to time travel across multiple subgenres and decades. We then evaluated each one—grading on a curve—with regard to its overall entertainment value and scientific logic, with the final combined score determining a film's spot on the overall ranking. For the “science” part of our scoring system, we specifically took three factors into account. First and foremost, does the time travel make logical sense? Second, is the physical mechanism of time travel somewhat realistic? And third, does the film use time travel in narratively interesting ways? So a movie like Looper, which makes absolutely no sense if you think about it too hard, gets points for weaving time paradoxes thoroughly into the fabric of the story.

(Many spoilers below in the interest of meaningful analysis.)

What modern science has to say about time travel can be summed up thusly: You can travel to the future, but you probably can’t travel to the past, although to be honest, we’re not really sure. Einstein’s theory of general relativity—which says that space and time are unified into “spacetime” and the curvature of spacetime gives rise to gravity—at least lets us contemplate the possibility of time travel in a scientifically plausible context. A “closed timelike curve” is a path through spacetime on which someone can move forward in time as far as their local perspective is concerned and nevertheless end up visiting their own past. Such a context, however, would involve astrophysically massive gravitational fields, possibly wormholes, and negative energies or something equally exotic. Essentially none of the films we will discuss even attempt to portray physically realistic time travel (with one exception, Interstellar, which is only a partial exception).

Even without scientific accuracy, we can still ask for logical consistency. Alas, that is also pretty thin on the ground, although in this case, there are true exceptions. The most straightforward way for travel to the past to make sense is if you can visit but you can’t actually change anything—“Whatever happened happened,” in the memorable formulation of fictional physicist Daniel Faraday in the TV show Lost. Physicists have dubbed this the “Novikov self-consistency principle,” but it can really just be summed up as “making sense.” Somewhat more ambitiously, we can imagine one or more alternative parallel timelines that are created by a sojourn into history. For the most part, however, our cinematic heroes make a cheerful hash of logic and narrative sense as they traipse through their pasts.

Here are our 20 representative picks, discussed in chronological order of their release to highlight how the understanding and treatment of time travel in Hollywood has evolved over the decades. There are some truly delightful entries here (plus a few stinkers for balance), but our deep dive into the topic has convinced us that the perfect time travel movie has yet to be made. That's a worthy goal for future filmmakers to strive for.