Deadpan satire and heartening embodiment of DIY enterprise, Shane Carruth’s repeat-viewing brain twister unites physics and metaphysics in an ingenious guerrilla reinvention of cinematic science fiction: Its analog-egghead approach may be the freshest thing the genre has seen since 2001. Less H.G. Wells than J.G. Ballard, Carruth’s prodigious no-budget debut is also the nerdiest and most plausible time-warp fantasy that movies have ever dreamed up. At once clinical and lyrical, practically compactor-pressed at a mere 78 minutes, Primer exists in a haze of naturalistic confusion. Fitting for a film about the limits of knowledge, it doubles as an experiment in narrative inference. Scenes begin and end in medias res. Meaning is elided, occluded, or embedded in texture and ambience. Visual ideas keep pace with the onslaught of hard science, and the overlapping dialogue, a rush of lab-speak gobbledygook that at times resolves into a sort of techie poetry, suggests David Foster Wallace rewriting David Mamet. Carruth’s commentary track clears up some, but by no means all, of the film’s mysteries.