I consider myself a reasonably bright guy. I’m no scientist, but I’ve read a few pop-sci books (A Brief History of Time, The Elegant Universe) and I feel like I understand the concepts well enough. Not only that, I’m a pretty big sci-fi nerd, and have loved the concept of time-travel since I was a little kid. That being said, the first time I watched the movie Primer it made my brain go “ow.” The plot follows the exploits of two Dallas-area engineers named Abe and Aaron, who stumble upon the ability to travel backward into time by accident while attempting to construct a gravity-degrading superconductor in their garage. They become aware of the enormous space/time implications as they become more brazen in their use of the machine, which causes some serious time-fuckery. I really thought I was following everything just fine for the first 2/3rds, but by the last half hour I was wallowing in a puddle of my own mind-goo. Abe and Aaron travel backward in time again and again, creating duplicates of duplicates as the plot’s comprehensibility (and the quality of their penmanship) disintegrates. As the movie wore on, it became increasingly unclear which timeline I was watching, and which copy of the characters were acting out the increasingly byzantine script.
And I loved every second of it. I watched it again shortly thereafter, and understood a bit more. A few months ago, I watched it for a third time, and just recently for a fourth — enough to think that I have a pretty decent grasp of the film’s machinations. It really is a sneaky little fucker, but there is a lot of pleasure to be had in unraveling its structure. Which makes this temporal map of the movie’s time-lines such a great resource. Taken by itself it’s nearly as confusing as the movie, but used in conjunction it can be an invaluable, ah, Primer primer.
Also worth checking out is this A.V. Club article about Primer and the “New Cult Canon.” It has a few clips from the movie and provides a more thorough explanation of the film’s creation and plot.