Primer is a 2004 American science fiction film about the accidental discovery of time travel. The film was written, directed and produced by Shane Carruth, a mathematician and a former engineer, and was completed on a budget of $7,000.
Primer is of note for its extremely low budget, experimental plot structure and complex technical dialogue, which Carruth chose not to ‘dumb down’ for the sake of his audience. One reviewer said that “anybody who claims [to] fully understand what’s going on in Primer after seeing it just once is either a savant or a liar.” The film collected the Grand Jury Prize at Sundance in 2004 before securing a limited release in US cinemas, and has since gained a cult following.
The operation of time travel in Primer.The principal characters are Aaron (Shane Carruth) and Abe (David Sullivan), two engineers who create a device which will allow an object or person to travel backward in time. The pair initially use the device to cheat on the stock market, but are ultimately unable to resist the temptation to meddle with every aspect of their lives. Through recklessness they create increasingly complex paradoxes, and ultimately their newfound power begins to destroy their friendship.
The film is set in the early 21st century and takes place in the industrial park and suburban tract-home fringes of an unnamed U.S. city. Four engineers—Aaron, Abe, Robert, and Phillip—work for a large corporation during the day, and run a side business out of Aaron’s garage at night, building and selling error-checking devices for computer motherboards. With the proceeds of this work, they fund pet science projects.
After an argument over which project the group should tackle next, Aaron and Abe independently begin work on a device which reduces the weight of any object. Although the device works as intended, it has an unexpected side effect: Abe discovers that they have accidentally created a time machine. He tells Aaron, and after some experimentation, they cut Robert and Phillip out of the group on the pretense that the garage has to be fumigated.
Abe and Aaron build two more machines—all of which are referred to as “the box” throughout the film—each large enough to hold a person. Their utility is limited compared to traditional depictions of time travel: the boxes can only transport the user to a point in time during which they are switched on, and only at “normal” temporal speed. For standard use as a time travel device, the box is activated at the point in time the user wants to travel back to. Once the user wishes to travel back to this point, they turn off the machine and, before it “winds down”, enter it. They remain in the box for the amount of time since it was activated, and may then exit at the point of activation. For example, if the machine is turned on at noon, and the user waits six hours until 6 p.m., then turns off and enters the machine and waits a further six hours, they will exit at the original activation point of noon. Staying in the machine would cause the user to continuously cycle back and forth between 6 p.m. and noon, with the ability to exit the machine at either endpoint. Getting out of the machine before reaching an endpoint causes a severe physical reaction—so Abe and Aaron never leave the machine early.
Abe and Aaron initially use the time machine to cheat on the stock market, but as their views on how the time travel works evolve, they gradually become more adventurous with their trips. Their experimentation is cut short by the unexpected appearance of Thomas Granger (Chip Carruth), the group’s original sponsor, who has apparently used one of the boxes to travel back in time for unknown reasons (the film’s voiceover remarks that the reason is “unknowable”). Granger collapses and becomes comatose, Aaron remarking it only seems to happen when he is near or in contact with Abe. Abe is disturbed by this turn of events, ultimately concluding that time travel is too dangerous. He subsequently attempts to prevent his past self from using the machine for time travel—thereby nullifying all of its consequences—by using another machine, that he built secretly, to travel back to a point prior to his broaching the subject of time travel with Aaron.
However, Aaron has already found this “failsafe” machine and has been using it to repeatedly redo the events of a party in which an attendee enters with a shotgun, intending to use it on Rachel Granger; Aaron attempts to intervene and get the gunman arrested so that he can become a hero, also concerned that his later actions are unpredictable if he were not stopped. Aaron has also replaced the failsafe with a duplicate—which he took back in time using the “real” failsafe—preventing Abe from undoing Aaron’s actions.
Having travelled back in time using the duplicate failsafe machine, Abe goes to meet Aaron and collapses. It is revealed that Aaron has been using a recording to recite their conversation from earlier in the film. After realizing that Abe has used the duplicate failsafe, Aaron explains himself. He has actually used the failsafe twice by this point. His first attempt ended in failure so he went back again, this time with a recording of his conversations from the first attempt to prevent changing events excessively. After encountering and fighting with the previous version of himself (who went back the first time), they agreed to let the Aaron who went back twice to continue his attempts.
The pair begins to experience side effects from time travel, including bleeding from the ears and difficulty with writing. They agree to try to change the events of the party together and eventually succeed. With their mutual deception of one another destroying their friendship, and their very different views on the use of the machines for time travel, they part ways. Aaron leaves the country, while Abe stays behind to continue his plan of attempting to prevent the doubles of Aaron and himself—who have no idea of what the others have done—from ever using the machines for time travel, suggesting that he would tamper with the machines in the hope that their doubles would think the experiment a failure and move on to other projects.
It is revealed that the narrator of the movie is the Aaron who came back in the failsafe the first time, and that his “narration” is actually a message being left on Aaron’s (the “original”, who does not yet know about the time travel) answering machine. The last scene in the film shows “narrator” Aaron instructing a team of French-speaking workers to line the walls of a warehouse with metal plates, as he begins construction on a building-sized machine (an idea he had shared with Abe earlier in the film).