Primer is a 2004 American independent psychological science fiction film about the accidental discovery of time travel. The film was written, directed, produced, edited and scored by Shane Carruth, who also stars with David Sullivan. Primer is of note for its extremely low budget, experimental plot structure, philosophical implications, and complex technical dialogue, which Carruth, a college graduate with a degree in mathematics and a former engineer, chose not to simplify for the sake of the audience. The film collected the Grand Jury Prize at the 2004 Sundance Film Festival, before securing a limited release in the United States, and has since gained a cult following. Plot Two engineers, Aaron and Abe, supplement their day jobs with entrepreneurial tech projects, working out of Aaron's garage. During one such research effort, involving electromagnetic reduction of objects' weight, the two men accidentally discover an 'A-to-B' causal loop side-effect: objects left in the weight-reducing field exhibit temporal anomalies, proceeding normally (from time 'A,' when the field was activated, to time 'B,' when the field is powered off), then backwards (from 'B' back to 'A') in a continuously repeating sequence, such that objects can leave the field in the present, or at some previous point. Abe refines this proof-of-concept and builds a stable time-apparatus ("the box"), sized to accommodate a human subject. Abe uses this box to travel six hours into his own past—as part of this process, Abe sits incommunicado in a hotel room, so as not to interact or interfere with the outside world, after which he enters the box then waits inside the box for six hours (thus going back in time six hours). Once he exits the box, Abe travels across town, explains the proceedings to Aaron, and brings Aaron back to the self-storage facility housing the box. At the facility, they watch the earlier version of Abe enter the box. Abe and Aaron repeat Abe's six-hour experiment multiple times over multiple days, making profitable same-day stock trades armed with foreknowledge of the market's performance. The duo's divergent personalitiesAbe cautious and controlling, Aaron impulsive and meddlesomeput subtle strain on their collaboration and friendship. Additionally, the time travel is taxing on Abe and Aaron's bodies; effectively their days become 36 hours long when including the extra time afforded by the box. As the film progresses, the two men begin to notice alarming side effects of time travel which take the form