Every day we face thousands of decisions, from big deal questions like, "Which job should I pursue?" to the minuscule, such as "Which shirt should I wear?" Each decision has a consequence, and at the end of the day, these outcomes make up our lives. The 2013 science-fiction thriller "Coherence" tackles the many-worlds theory in a mind-bending multiple-reality experience on a limited budget and shooting schedule (shot over the course of only five nights in director James Ward Byrkit's own home).
The film begins with four couples gathering for a dinner party. None of the characters seem completely satisfied with their lives, including our protagonist, an unsuccessful dancer named Em (Emily Foxler). Out of pride, she was once hesitant to take an understudy role—a role which later jump-started another dancer's career. While she doesn't outright say it, we can infer that part of what's so frustrating is the "what-if" mentality. Would the role have taken her as far as Katherine Merris, the dancer who ended up taking it? Following Em's story, another guest, Hugh (Hugo Armstrong), toasts, "Here's to the life that we do lead."
The audience begins to detect that something is afoot when the internet goes down and no one has cell-phone service. Mid-dinner, the lights also go out, prompting Hugh and Amir (Alex Manugian, who co-wrote the film with Byrkit) to go out in search of a house with a landline. More strange occurrences accumulate throughout the evening. What began as a small relationship-fueled drama becomes a somewhat philosophical exploration into human nature, fueled by a pseudo-scientific discovery of multiple realities. They discover houses set up like their own, photos of themselves where they shouldn't be, and notes appearing before they've been written.
Throughout the night, characters frequently speak over and interrupt one another, a refreshing and true-to-life aspect of the film. This makes sense, given that while Byrkit was developing the plot, he didn't write a script. Instead, he guided the actors by giving them notes about their character's backstory and motivations each day before filming, allowing them to improvise. While this gives the film natural dialogue, there are some drawbacks—the focus on improvisation means that characters sometimes make decisions that seem unrealistic, even for a group grappling with the reality-shattering realizations that unfold throughout the evening.
The group cobbles together an explanation, based on Em's cursory interest in Miller's comet (a comet flying unusually close to earth that evening) and Hugh's brother's notes on the quantum physics thought experiment "Schrödinger's cat" (which he's conveniently left at the host's house). While we don't know how much of the group's half-baked explanation is true, as the evening progresses, we come to realize that each choice the characters face has the potential to create another reality—one for each possible decision. For the time being, they're able to enter these other versions of their lives, leading first to confusion, and then to paranoia. What's fascinating is that their paranoia derives not from what they think others are capable of, but from what they know themselves to be capable of. By the end of the film, we're left wondering how far we'd all be willing to go to sacrifice the life we lead for a more attractive one.