Coherence is a 2013 American surreal science fiction psychological thriller film directed by James Ward Byrkit in his directorial debut. The film had its world debut on September 19, 2013, at Fantastic Fest and stars Emily Foxler as a woman who must deal with strange occurrences following the close passing of a comet.

Plot

On the night of Miller's Comet's passing, eight friends gather for a dinner party at the home of couple Mike and Lee. Emily is hesitant to accompany her boyfriend Kevin on an extended business trip abroad. Amir has brought Kevin's ex-girlfriend Laurie, who flirts inappropriately with Kevin.

A power outage occurs. Mike and Lee bring candles and different colored glow sticks. The friends each take a blue glow stick and venture outside where the neighborhood is dark but for one house that has lights. Back inside, they notice a broken glass no-one remembers damaging. Amir and Hugh decide to ask to use the phone at the lit-up house, as Hugh's physicist brother insisted Hugh call him if "anything strange" were to happen during the comet's passing, and no one's mobile phone has signal.

Hugh and Amir return. Hugh has a cut forehead and Amir has brought back a box containing a ping-pong paddle and photographs of everyone with numbers written on the backs. Hugh says he saw through the window of the other house a table set with eight places. They realize the other house is an alternate version of theirs.

Hugh writes a note to leave at the other house, only to find an exact copy of the note pinned to their own door. Emily, Kevin, Mike, and Laurie decide to go to the other house. On the way, they encounter another group of four, carrying red glow sticks rather than blue. Each group flees back to their houses.

Hugh retrieves his brother's book from his car, which deals with quantum decoherence. They speculate that the comet has created two split realities, one of which will collapse once the comet has passed. They surmise that anyone passing through the area of particularly dense darkness outside will emerge into a different reality. Mike drinks heavily and considers killing their doubles before the doubles can kill them. He decides to write a blackmail note to the other Mike to keep him from the book.

The group realizes Hugh and Amir, in their midst, came from the other house. The two take the box and leave, then return carrying blue glow sticks. They had found two notes at the other house, showing that the split created more than just two alternate realities. Beth sees Laurie kissing Kevin in the hallway. Someone outside smashes Hugh's car window. Emily retrieves the ring Kevin gave her from her car. Talking to Kevin, Emily realizes he is from a different reality.

The group creates their own box to validate they are all from the same reality. As well numbering the photographs by rolling dice, they include a randomly chosen object. Emily deduces that only Lee and Beth, who never left the house, originate from that house; that herself, Kevin and Laurie are from a different house; Hugh and Amir are from a third house; and Mike is from a fourth. The blackmail note arrives under the door, revealing an adulterous liaison between him and Beth. Another Mike breaks in and attacks his double then leaves.

Emily goes out and looks into several alternate houses, finding different situations including one in which no one seems aware of the split. She lures everyone out of the house by smashing Hugh's car window, then ambushes the alternate Emily and injects her with ketamine when she gets her ring out of her car. She takes her other self's place while Miller's Comet breaks apart overhead, but must subdue the other Emily again when she crawls into the bathroom. She takes the ring from her defeated self after losing her own in the altercation, then when returns to the living room and faints.

Emily wakes in daylight on the sofa with the rest of the party apparently none the wiser. Kevin returns her ring which he found in the bathroom. His cell phone rings and he notes that, weirdly, it is Emily calling. Emily looks at the two rings as Kevin answers the phone, then he turns to look at her with the phone to his ear.

Cast
 Emily Foxler as Em
 Maury Sterling as Kevin
 Nicholas Brendon as Mike
 Lorene Scafaria as Lee
 Hugo Armstrong as Hugh
 Elizabeth Gracen as Beth
 Alex Manugian as Amir
 Lauren Maher as Laurie
 Aqueela Zoll played one copy of Emily when there were two of them in one scene
 Kelly Donovan, the real-life identical twin brother of Nicholas Brendon, played one copy of Mike when there were two of them in one scene

Production

Development
Byrkit came up with the idea for Coherence after deciding that he wanted to test the idea of shooting a film "without a crew and without a script". He chose to shoot in his own home and developed the film's science fiction aspect out of necessity, as he wanted to "make a living room feel bigger than just a living room". While Byrkit did have a specific idea for how the film would unfold, he selected improvisational actors and gave them the basic outline of their characters, motivations, and major plot points.

Byrkit told an interviewer, "For about a year, all I did was make charts and maps and drew diagrams of houses, arrows pointing where everyone was going, trying to keep track of different iterations. Months and months of tracking fractured realities, looking up what actual scientists believe about the nature of reality—Schrödinger's cat and all that. It was research, but despite all the graphs and charts, I think our whole idea was that it has to be character-based. We want the logic of our internal rules to be sound, and we wanted it to be something people could watch 12 times and still discover a new layer."

The movie cuts to black at 0:02, 0:03, 0:05, 0:05, 0:07, 0:09, 0:19, 0:27, 0:32, 0:34, 1:06, 1:18, 1:22, and 1:23. The movie's director has said those cuts signify something but hasn't said what they signify. There was no cut to black around 0:16, which was the point of divergence between realities, although the house was plunged into darkness due to an electricity cut. There was no cut to black at 0:17 when the characters all switched from a house without a broken glass to a house with broken glass, and there was no cut to black at 0:46, when only Mike switched to a different reality.

Casting
Byrkit intentionally chose actors who did not know each other. He told an interviewer that, after working on blockbuster films (such as Pirates of the Caribbean: The Curse of the Black Pearl), "I come from the theater where I was trained to really just concentrate on story and character on a stage with actors and so I was craving getting rid of everything, getting rid of the crew; getting rid of the script, no special effects, no support, no money, no nothing, and just getting back to the purity of that, of a camera in your hand and some actress (actors?) that you trust and an idea."

Byrkit added, 

When asked whether the actors were people whom Byrkit knew pretty well, he answered, "Yeah exactly. They were just friends that I knew I could just call up and say, 'Show up at my house in a couple days. I can't really tell you what we're doing, trust me I'm not going to kill you. It should be fun!' And they didn't know each other before they got to my house and so I had to pick people that seemed to be like they could be couples, seemed like they could be best friends and that I just knew were up to the task of jumping into it."

Interviewer Nell Minow confessed her reaction to the actors' relationships: "I just assumed that they all knew each other very well because they fell into the kinds of rhythms that old friends have." Byrkit replied, "That's just casting great people that could do that. Just five minutes after they arrived at my house they had to pretend to be married and lovers and best friends."

Reviewer Matt Prigge praised the choice of casting and their actions: "Byrkit ... focuses not on brainiacs, as in Primer, but on smart but mostly under-informed NPR types, who know enough to slowly piece all this together but not enough that they don't usually descend into blabbering, shouting and drinking. Indeed, Coherence is largely improvised, with a game cast first believably under-reacting to some weird business with laughter and disbelief, then always maintaining a degree of levity (read: jokes and occasional put-downs) even when stuff has gotten real."

Writing
Ryan Lattanzio wrote, "Byrkit brought eight unwitting actors to his Santa Monica home, threw them a few red herrings and set them loose for five days knowing that the film could evolve organically, like great jazz, if he kept his players in the dark. But he and co-storywriter Alex Manugian weren't just making it up as they went along." Byrkit told him that his desire was "to strip down a film set to the bare minimum: getting rid of the script, getting rid of the crew."

Byrkit added, "... instead of a script I had my own 12-page treatment that I spent about a year working on. It outlined all of the twists and reveals, and character arcs and pieces of the puzzle that needed to happen scene-by-scene. But each day, instead of getting a script, the actors would get a page of notes for their individual character, whether it was a backstory or information about their motivations. They would come prepared for their character only. They had no idea what the other characters received, so each night there were completely real reactions, and surprises and responses. This was all in the pursuit of naturalistic performances. The goal was to get them listening to each other, and engaged in the mystery of it all."

Nicholas Brendon, an actor in the film, discussed the improvisational style of the dialogue with Mandatory journalist Fred Topel, who asked: "I understand the way Coherence was done was that everyone got notecards about their characters and the scenes. What was on your notecards?" Brendon replied, "I can't remember now, but every day we had five different things that we had to convey... but I do know that Jim [Byrkit], and then Alex [Manugian], the other writer, had to make sure that we were all on point. So it was just a matter of getting that information out. ... Since there was no script, I had no idea how it ended. ... When I saw the movie, I'm like, 'Oh shit, this is awesome!' ...  To be quite honest with you, I never really knew what was going on fully until I saw the movie done."

Filming
Principal photography took place over the course of five nights in Byrkit's house.

An interviewer asked Byrkit, "Did you run into any unexpected problems in filming?" Byrkit admitted, "... you're constantly dealing with unexpected things. One night we tried to shoot outside and we had to make the whole thing look completely desolate and the power being off; that was the one night that we had another movie shooting on our street. So the whole street is completely ablaze with lights and hundreds of extras." Another team was shooting a Snickers commercial. "We would be right in the middle of the dramatic scenes and there would be another knock on the door that would just scare the hell out of everybody ..."

Music 
The original score was composed by Kristin Øhrn Dyrud. The song in the closing credits is "Galaxies", from the album Year of Meteors by Laura Veirs.

Inspirations and themes
Byrkit told an interviewer for Spinning Platters, "Well, we came up with the premise in my living room, where the movie is shot. A couple of years ago we were trying to think about what a good low budget, or no budget, movie would be. And, since we didn't have any resources, I had to think of what we actually had.  We had a camera.  We had some actors who were pretty good, and we had a living room. So we had to find out how to make a living room feel like more than just a living room. And, that led to a whole Twilight Zone type story ... I was craving a more naturalistic type of dialogue, where people overlap and it's very messy, where people talk more like real humans talk.  And so, we planned the story for a year, including the twists and turns and reversals and betrayals so that we had a really tight puzzle – almost like a funhouse that we knew we could lead the actors through."

Some reviewers have suggested that Byrkit was influenced by the eeriness of The Twilight Zone and/or the mind-challenging complexities of the science fiction film Primer.

Byrkit answered one interviewer: "Twilight Zone, for sure. Primer wasn't really an influence so much as it was a sign to us that maybe there was an audience for this kind of movie. The actual movie itself is so different than ours that it wasn't as much of an influence as, say, Carnage by Roman Polanski, or other non-sci-fi movies."

Reception
On Rotten Tomatoes, the film has a rating of 88% based on 91 reviews. The site consensus says "A case study in less-is-more filmmaking, Coherence serves as a compelling low-budget calling card for debuting writer-director James Ward Byrkit." On Metacritic it has a score of 65% based on reviews from 23 critics, indicating "generally favorable reviews".

Much of the film's praise centered upon its cast, which Bloody Disgusting and Fangoria cited as a highlight. Film School Rejects gave Coherence a positive review, stating that the film's cast was "remarkably grounded for how complicated and bizarre the story is."

Dread Central commented on the film's themes and wrote, "What's frightening about the story is how willing the characters are to abandon the reality they know in favor of one that may be a little more appealing. Whether that's a byproduct of the comet and the rift it creates or caused by the characters undermining everyone else around them to get the life they really want is the fundamental idea of Coherence and what makes it so unsettling."

Clark Collis of Entertainment Weekly praised the film, granting it a B+ rating: "In an impressive big-screen debut from James Ward Byrkit, eight friends discover metaphysics on their menu when a passing comet creates a set of doppelgängers down the road, enjoying their own identical soiree. Byrkit makes the most of the claustrophobic one-house setting, ratcheting up the dread and paranoia as his characters make a string of seemingly reasonable but ultimately wrongheaded decisions. The star-free cast is great too, with Buffy the Vampire Slayer vet Nicholas Brendon poking fun at himself by playing an actor who used to be on a TV show ... Coherence is a satisfying and chilling addition to the ever-growing pal-ocalypse subgenre. And really, you have to love a film that not only explains the concept of Schrödinger's cat but also includes a joke about it ("I'm allergic!").

Stephen Dalton of The Hollywood Reporter also enjoyed the film: "An ingenious micro-budget science-fiction nerve-jangler which takes place entirely at a suburban dinner party, Coherence is a testament to the power of smart ideas and strong ensemble acting over expensive visual pyrotechnics ... A group of eight friends gather for dinner ... Marital tensions and sexual secrets sizzle just below the surface, but relationship drama is soon overshadowed by metaphysical weirdness when a comet passes close to Earth, shutting down power supplies and phone connections ... It slowly becomes clear that the fabric of reality has been radically remixed by the comet's arrival. We are definitely not in Kansas any more ... Byrkit only gave his cast limited information about the narrative loops and swerves ahead, encouraging a semi-improvised naturalism that feels authentically tense."

Matt Zoller Seitz, editor-in-chief of Roger Ebert's website, gives the movie three stars and writes that the film "is proof that inventive filmmakers can do a lot with a little ... [but] none of the movie's technical or artistic shortcomings prove to be deal-breakers. Once Coherence delves into its premise, the viewer is bound to come down with a bad case of the creeps. This is a less-is-more science fiction-horror tale ... And it's genuinely more of a horror film than a suspense or "terror" film because, while there's some violence, the source of unease is philosophical."

Ryan Lattanzio of Indiewire praised the film's originality: "Coherence is not just smart science fiction: it's a triumph of crafty independent filmmaking, made with few resources and big ambition. Gotham-nominated debut director James Ward Byrkit stripped his vision down to the barest of bones to achieve a mind-shifting, metaphysical freakout about a dinner party gone cosmically awry. This film explodes with ideas, and it has that thing we always hope for at the movies: the element of surprise."

The reviewer for Salon was ambivalent: "After the fundamental problem of Coherence has become clear, or clear-ish – there's another dinner party, at that other house, that looks an awful lot like this one – the movie becomes slightly too much like an unfolding mathematical puzzle, although an ingenious one that reaches a chilling conclusion. Notes appear before they are written, the significance of those numbered photographs comes into focus through a series of neat twists, and while the characters are half-aware that their actions are being shaped by a space-time continuum whose cause-and-effect relationship has gone awry, that's not enough to stop them."

Accolades
 Next Wave Best Screenplay at the Austin Fantastic Fest (2013, won)
 Maria Award for Best Screenplay at the Sitges Film Festival (2013, won)
 Carnet Jove Jury Award for best In Competition at the Sitges Film Festival (2013, won)
 Black Tulip Award for Best Feature Debut at the Imagine Film Festival (2014, won)
 Imagine Movie Zone Award, Special Mention at the Imagine Film Festival (2014, won)

See also
 Many-minds interpretation
 Many-worlds interpretation
 Multiverse
 Everything Everywhere All at Once
 "The Garden of Forking Paths", a 1941 short story by Argentine writer and poet Jorge Luis Borges

References

External links
 
 
 

2013 films
2013 independent films
2010s science fiction thriller films
American independent films
American science fiction thriller films
Comets in film
Films about parallel universes
Films set in California
Improvised films
Time loop films
2013 directorial debut films
2010s English-language films
2010s American films