Movie Review Coherence: False beacons in a fractured multiverse

The colored glow sticks in James Ward Byrkit’s 2013 film represent a futile attempt to impose order on quantum chaos. Shot for $50,000 over five nights with improvised dialogue, the glow sticks become the film’s visual language. Through them, eight dinner party guests attempt to track their identities across infinite parallel realities. Their failure is the point.

CONTAINS SPOILERS

James Ward Byrkit's Coherence begins with eight friends at a dinner party. A rare comet passes overhead, rumored to have strange effects on the world.
That danger becomes immediate when phones stop working and the power goes out, while a neighboring house remains strangely lit. What follows is not an explosion of special effects, but a rough collapse of certainty.
The group slowly realizes that multiple versions of themselves may exist simultaneously, and that the lit house is not a neighbor at all, but another timeline in which the same dinner party is taking place.
Their response is perfectly human. They try to organize the chaos. Colored glow sticks become the solution. Blue for this house. Red and green for the others. A system meant to track who belongs where.

Ever since watching the film, I have been intrigued by the glow stick element. That is why this review focuses on that single detail, and on what it reveals about the film as a whole.

The tracking system starts simple

When Miller's Comet passes overhead and plunges the dinner party into darkness, host Mike retrieves glow sticks from his earthquake kit. He offers three boxes—blue, red, green.
The group chooses blue and each person takes one.
Initially the choice for the colour is random and not yet used as an identification system, that becomes important later.

Because, across infinite parallel realities, other versions of the same group have chosen their own glow-stick.
Director Byrkit called them "The Barrels," hoping they'd function like the yellow barrels in Jaws. When you see the barrels, you know the shark's underneath.

When Emily, Mike, Kevin and Laurie venture outside to investigate a lit house down the street, they bring their blue glowsticks.
They encounter another group of four who look exactly like them, carrying red glow sticks instead of blue. Both groups flee in terror.

The friends speculate, and are soon forced to believe, that other realities exist alongside their own. It is at this point that the glow sticks become an identification system.
The initial logic seems straightforward. Blue equals our house. Red equals theirs. The characters believe they have discovered a reliable form of authentication.
But with a limited number of colors and an infinite number of universes, the math already signals the futility of imposing order on chaos.
The group quickly expands the system into something more elaborate. Marker boxes are created, containing photographs, dice-rolled numbers written on the back, ink colors matched to glow sticks, and a random object assigned to each person.
A ping-pong paddle. An oven mitt. A stapler. A coaster. A napkin. Anything seemingly random turns out to be somewhat not random.

The problem is that the others are doing the same. Again, it becomes a matter of numbers and probability. The mathematical complexity is staggering. Hugh calculates 5,038,848 possible combinations.
The characters believe this accumulation of data will protect them from imposters and allow them to verify who they are.

They are wrong. Very wrong.

The system collapses

The breakdown comes when Hugh and Amir, who left earlier to find a working phone, return to the house. Mike confidently states that everyone present has blue glow sticks. Hugh and Amir are forced produce theirs.
It turns out to be red, not blue.
These two men carry the wrong color. They're not from this reality. They crossed through the dark zone and entered a different house without realizing it.
The original Hugh and Amir who left the blue glow stick house are gone forever, wandering somewhere in the multiverse.
The horror deepens when another Hugh and Amir arrive later, these carrying blue glow sticks. The tracking system hasn't just failed once.
It's collapsed entirely. Multiple realities share the same glow stick color.

The dark zone gambles your reality

The "dark zone," a particularly dark area outside the house, serves as the portal between realities. Anyone crossing through emerges into a different parallel universe, like a ball on a roulette wheel.
Characters can't choose which reality they enter. Each trip outside gambles that you might be stranded forever in an unfamiliar timeline.
Byrkit explained the significance of the film's black cuts. "Once we tried that editing thing, we realized that thematically it's all about the lights going out, these dark spaces.
The dark zone embodies quantum physics' measurement problem. The comet temporarily breaks quantum decoherence, allowing normally separate realities to overlap.
Crossing the dark zone is the observation that determines which reality you inhabit.

The title is deeply ironic

In quantum physics, coherence refers to a system maintaining superposition, existing in multiple states simultaneously.
Decoherence is when interaction with the environment causes superposition to collapse into classical reality (a perceived singular reality).
Under normal circumstances, quantum decoherence keeps parallel universes separate.
The comet breaks this rule, creating temporary coherence between realities that should remain separated.

This is when the film explicitly invokes Schrödinger's cat.
The characters realizes their situation. "We're in the box. We're the cat. We're both alive and dead."

By the ending, Emily literally becomes Schrödinger's cat, hidden in a trunk, existing in an indeterminate state until someone opens it.

Emily goes shopping for better timelines

Emily begins the film as a sympathetic figure, a dancer whose career stalled when another woman replaced her in a major production. She refused the role of understudy, allowing pride to cost her everything.
This establishes a quiet regret over missed opportunities, which, when confronted with infinite what-if scenarios in the multiverse, mutates into something far more dangerous.

As the chaos escalates, Emily realizes she can actively search for a better version of her life. She ventures outside again and again, moving between houses, looking for a reality in which things unfolded differently.
When she finally finds one, a calm dinner party where her relationships remain intact and her counterpart’s life appears better, she makes a devastating choice.

Emily knocks out her alternate self and attempts to take her place, hiding the unconscious double in a car trunk.
Earlier,
Emily complained about the dancer who stole her life. Now she does the same to another version of herself.
The glow sticks, once meant to identify friend from foe, become irrelevant.
The greatest threat Emily faces is herself.
Or at least, that is the assumption this reading makes. Whether another version of you can truly be called the self is a question Emily clearly does not ask.

Emily wakes in the better reality believing she has succeeded.
Morning light suggests the comet has passed. Reality should be fixed, right?
But then someone finds her ring in the bathroom, but she is wearing one too.
Two rings exist and suddenly other Emily is calling from outside.

The cat was clearly not dead.

The screen cuts to black. Emily faces an impossible reckoning.
The Emily she knocked unconscious has awakened and is reclaiming her timeline.

How would you face yourself I wonder?