Last night, I went to see the new Tom Cruise and Emily Blunt science-fiction film Edge of Tomorrow, which is based on the Japanese manga All You Need Is Kill.

The racial cross-casting of Cage’s character — he is inspired by Japanese protagonist Keichi in the manga — aside, this film is phenomenal. Nerds and feminists — and especially nerd feminists — will adore this movie. It’s sharp, funny, entertaining, compelling, and visually stunning. Haters of Tom Cruise get to see Tom Cruise get killed about a hundred times in stunt scenes that Cruise himself described as “channeling Wile E. Coyote” on Daily Show last night. Emily Blunt’s Rita is stellar: she is the aspirational super-soldier, and not the simpering girlfriend; she’s also got a bad-ass giant sword. Those who loved Pacific Rim‘s portrayal of a male-female peer relationship that was largely non-sexual will adore the relationship between Rita and Cruise’s Cage in this film.

Basically, it’s just really good. Go see it. I’ll wait.

Okay, now that you’ve seen it — did you have all kinds of thoughts and questions about those aliens and the “time travel” in this movie? Snoopy and I did, too, and we geeked out over a late-night dinner about the science of how what happened could have happened. Here’s what we came up with, and I’m posting about it because — goshdarn it — I think we really figured this thing out.

Spoilers! This post will spoil the entire movie.

Okay, so the conceit of the film is that these aliens, called Mimics, have a looping “time travel”-like power that allows them to reset a day, memories intact, whenever they are in danger. That power gets transferred to Cruise’s Cage, setting the whole film off. All You Need Is Kill has a similar conceit, but from the manga’s Wikipedia page, other aspects of the Mimics seem different than those of Edge of Tomorrow. So this post is going to treat the Edge of Tomorrow Mimics as if they are stand-alone.

The “time travel” of the Edge of Tomorrow Mimics isn’t really time travel, it’s consciousness-travelling (similar to the conceit of the travesty that was X-Men: Days of Future Past): the Mimics — and by extension Cage — are not physically travelling from one timepoint to another; instead, their minds are jumping backwards to an earlier timepoint, allowing them to alter the course of time by making decisions informed by a possible future.

But, how does this really work? What is the relative role of the Alphas (the glowing sentinel Mimics) and the Omega (the central core that Snoopy thought was heavily inspired by Starship Troopers‘ Brain Bug)? And, isn’t this just one giant incubator for alternative universes? (To that last point, the answer is yes.)

There are two clues: 1) the Mimics are actually a single organism with each individual Mimic type acting in tandem with the whole, and 2) the “resetting” power always bringing Cage back to the same point in time. The key is to think about the Mimics not as some evil, super-intelligent being; instead, think of it as a creature acting purely on instinct. Think of it like biology.

The Mimic is an organism whose sole purpose is to conquer planets, and has evolved a complex self-defense mechanism to ensure its own propagation. The Mimic drones are the “claws” — the Mimics’ primary defense system. The Alphas are “sentinels” that exist to gauge the degree to which any threat makes it past the drones; if something kills an Alpha, this indicates sufficient danger to instinctively trigger the Mimics’ final self-defense mechanism: the looping.

And how does that work? In addition to its primary function to coordinate the actions of all drones and Alphas, the Omega has an additional characteristic. The Omega Mimic exists simultaneously at three points in time. If you think of time as a linear dimension, each of us occupies a single point on that line. The Omega Mimic exists instead as a line connecting three points spanning an approximate 48 hour period: the “distant past”, the “present-past”, and the “future-present”. The “present-past” point serves as the main anchor point: a fixed position in time from which to (routinely) reset the day. From that point in time, the Omega extends a version of itself towards the “future-present” like a cell that moves by extending a tendril ahead to test a space out to see if it’s safe.

And, like cells, if the Omega encounters danger in that future (as evidenced by the death of an alpha) it instinctively retracts back to its first anchor point and tries going in a different direction.

And what about the “distant past”? That’s a reserve anchor point that allows the Omega to reset from even farther back in time, allowing it to never be fully committed to a single temporal direction. If things get really dicey, it will retract far enough away to move in a completely different direction, entirely. If we think of it spatially, the “present-past” and “future-present” are like taking steps after deciding to go left; the “distant-past” exists as a mechanism to abandon going left entirely.

So how did Cage get the power to loop? Well, the Alphas are “sentinels”: as deadly as a drone, but their true power lies in their blood. If the looping power is a final self-defense mechanism for the Mimics, than the death of an Alpha would be the trigger to initiate a reset. Mixture of Cage’s blood with a dying Alpha (somehow — this is never explained and defies biology) integrated Cage into the Mimic’s network of sentinel Alphas. In essence, as far as the Omega was concerned, he was another Alpha. Every time Cage died, the Omega mistook this for a signal that it was in danger and triggered a loop.

Cage was never in control of the looping power. The Omega was being fooled into looping by thinking Cage was an endlessly dying Alpha sentinel.

Update: (I solidified this particular detail after this post was written, so am adding it now). The “time travel”, specifically, is psychic-based and is channeled through the Omega. Basically, when the Omega is given a signal to loop, it pulls a clone or mirror of all the memories of all its network of itself and its Alphas (probably not the drones, that’s huge amount of processing for limited gain) and creates a copy of those memories in the Omega. Then, it sends that entire data package through itself to the “present past” anchor point, and then redistributes those memories out to the Mimic network (and to Cage, who is a pseudo-Alpha). From the perspective of an Alpha, this would appear to be like you just traveled back in time, but really you just got all the memories and life experiences of a future Cage who made different choices.

So, why did the Mimics send him to the dam and why didn’t they try to kill him when he was there? Well, an organism that evolves such a complex self-defense mechanism will also likely have a mechanism for repairing problems when they arise. In this case, this “time travel” self-defense mechanism has one serious flaw: it would trap the Omega in a perpetual loop if there were an Alpha that was weak or broken, endlessly throwing itself into harm’s way when there isn’t sufficient danger to warrant a “reboot”. There needs to be a self-repair mechanism for the Mimics to identify and correct such a problem.

The visions seen by Rita, and then later by Cage, were intermixed with their own memories (hence Cage sees the dam just as he reboots), and it is this repair system taking effect: the Omega sent a specific signal that would attract Alphas to a single location, where they could be safely disposed of far away from the location of the Omega itself (this is to keep the Omega safe in case the defective alpha is dangerous). When Cage arrived at the dam, the drone and the Alpha stopped Cage from killing himself because they don’t want to loop again, since the whole point of the mechanism is to stop unnecessary looping. It’s unclear what they would’ve done to Cage if he hadn’t killed himself, but most likely if he had been an actual Mimic, they would have removed him from the “sentinel” network by performing a process similar to the blood transfusion, and then killed him. That’s why the Alpha wounded him, but didn’t kill him.

So what about that ending?

After a blood transfusion, Cage is essentially excised from the Alpha network, no longer being mistaken by the Omega as a “sentinel”. And then stuff happens and he kills the Omega by dropping a bunch of grenades into it. But then he wakes up in the helicopter at the start of the film and all is right with the world?

Well, at the moment of his death, Cage’s blood mixes with that of an Alpha, and he temporarily becomes a pseudo-Alpha again, which allows him to retain his memories in the reboot. Meanwhile, because the Omega was itself dying, one final loop was triggered by the Omega in a final desperate attempt to escape danger. The Omega looped not to the “present-past” point but to the “distant past” anchor point since the Omega itself wanted to escape an imminent threat to its core. Because of the Alpha’s blood, Cage went along for the ride and woke up with the Omega at the “distant past” timepoint.

But, since the Omega exists at multiple points in time (rather than a single moving point) and was actually killed in the “future-present”, the explosion actually rippled back in time and killed the Omega at all the other time points, too. So, when Cage wakes up, he wakes up at the “distant-past” anchor point along with his memories at the precise position in time that the Omega kept anchored to in reserve, and when it blows up. This allows for the lovely ending where everyone we watched die horrifically in the movie get to live again in blissful ignorance.

And does Cage now have time-traveling powers? Is he immortal? No. Being an Alpha only ever meant he was a sentinel, invoking the looping powers of the Omega upon every death. He could never himself loop. With the Omega dead, Cage is back to being a normal dude with one final lease on life.

So, what do you think? Does this make sense? Or is this all the mad ramblings of one non-physicist fangirl? I would love to hear your thoughts!