You'd expect a diversity of plotlines given the number of time-travel stories we've seen, but most really fall into two simple categories:
1. One where the course of time is immutable: Actions in the past are exactly what has already happened, and the future is inevitable. (An archetypal example is Robert Heinlein's short story "By His Bootstraps.")
2. One where the course of time is malleable: The present can be changed by making changes in the past, aka the butterfly effect. (An archetypal and namesake example is Ray Bradbury's "A Sound of Thunder.")
There are a few genre-defying exceptions to these, films like Groundhog Day, where the main character is caught in a recurring time loop, and Inception, where the perception of time is all in the mind. And now with Looper, we're presented with another exception -- a time-travel scenario that keeps us guessing with aspects of both archetypal plotlines. Some even argue it's not a time-travel movie.
Regardless of how we classify it, the key question Looper presents is: Can modifying the past significantly affect the future, or are some outcomes inevitable? While some aspects of the film clearly indicate that we can change our futures by changing our pasts, the open question we're left with is whether Joe really is able to successfully alter a probable future?
*Noah Iliinsky is the author of Designing Data Visualizations and the technical editor of *Beautiful Visualization, both published by O'Reilly Media. Iliinsky has a master's degree in technical communication from the University of Washington and a bachelor's degree in physics from Reed College in Oregon. He has spent the last several years specializing in approaches for complex diagrams and data visualizations.
