What with life being a nonstop assault of baffling choices and thundering confusion, I usually find it barrel-throwingly annoying when a movie does the same thing. If I want things I can't possibly understand, I'll just comb my hair into my eyes and sneak into a high school classroom.
But time travel is messier than that bathtub where I throw my used dishes. Most movies address the paradoxes in some form, but none does it with more drooling-down-your-shirt havoc than 2004's Primer.
While working on an unrelated device, engineers David Sullivan and Shane Carruth inadvertently discover a process that lets them travel a short distance back in time. Initially, they use it to get rich in the stock market, but soon the temptation to improve their personal lives drags them into a web of paradoxes from which there might be no escape.
Primer is the cinematic equivalent of slugging a pint of Black Velvet, then having your door kicked down by a robo-tripping mathematician who makes you solve calculus problems at gunpoint. Right off the bat, Carruth (who wrote, directed and handled just about everything else short of churning the butter for the crew's toast) leavens the dialogue with tech-heavy shorthand that's total gibberish to any of us who don't run that power plant down the road.
The plot's no clearer. Carruth and Sullivan soon discover they have literally no way to know what changes their future selves might make. Untethered from causality, things happen that can't be understood by the characters themselves, let alone the viewer.
It's frustrating at times, but that's the point: in a realistic depiction of time travel, existence goes insane. Carruth captures the madness by slashing Primer's exposition down to the roots. It's just short of impenetrable.
Unlike Donnie Darko, Primer doesn't have an expansive world to get distracted by as the rest of your brain huffs and puffs to figure out what's happening. It's just a mudslide of confusion, paranoia, and mounting distrust I'm pretty sure the reason we've never seen any time travelers is because the first thing they do (once they stop shaking) is rush back to feed their mothers pennyroyal tea.
This is a challenging movie, which is often critic-code for "stiff intellectual exercise that's better to hear about than actually watch," but this one's different. It's worth remembering that feeling all whacked out in the think-box is how you're supposed to feel. If you ever plan on going back to warn yourself to avoid that crab dip, Primer's a priceless field guide.