Marvel Cinematic Universe: How does time travel work?

Season 5 of Agents of SHIELD may have confirmed how time travel works in the Marvel Cinematic Universe.

The Marvel Cinematic Universe will soon receive its latest season of television, as we’re less than a week away from the two-hour premiere of Agents of S.H.I.E.L.D. season 5. That means Marvel’s putting a lot of effort into marketing the show, right down to releasing the first 17 minutes on YouTube.

It’s an astounding clip, confirming that the S.H.I.E.L.D. team are boldly going where no S.H.I.E.L.D. agent has gone before. Intriguingly, it’s also revealed that this season will see a major time travel arc. Coulson and his gang haven’t only been taken into the depths of space. They’ve also been abducted through time, transported to a future in which they are legends.

So how does time travel work in the Marvel Cinematic Universe anyway? Surprisingly, this brief clip has just told us everything we need to know.

Time travel and Agents of S.H.I.E.L.D.

Let’s start with a brief flashback to Agents of S.H.I.E.L.D. Season 3. One episode, “Spacetime,” introduced the team to an Inhuman with the power to see the future. This became an intriguing plot, with S.H.I.E.L.D. attempting to avert Daisy’s death at the hands of Hive. They even trained May to take over Daisy’s mission, but had to change plans when May’s husband Andrew began to transform into Lash once again. In the end, it turned out the vision had been misinterpreted. This wasn’t Daisy’s death after all. Instead, it was the death of the precog himself.

Significantly, the same episode saw Fitz insist that the future could not be changed. Fitz ascribed to a model of time in which time is immutable and unchanging. The past is fixed, and anything you see or experience in the future becomes fixed as well.

That’s our first hint of how time travel could work in the wider MCU. Fitz’s argument would be that time travel is possible, but you can’t actually change anything. The clip from Season 5 suggests exactly the same model of spacetime. The “True Believers” knew that Coulson and his team had to be brought from our time to their own. They knew this because they’d studied S.H.I.E.L.D.’s history. They knew that the agents would be taken to the future, and there would save the human race. Season 5 is kicking off with a story in which the group’s actions are essentially preordained by the very nature of time travel.

Is there an exception to this rule?

As fascinating as this model of time travel may be, it’s worth noting that there’s already an exception to the rule. Doctor Strange revealed that there is one object that can override the normal nature of spacetime. Wielding the Time Stone, Strange was able to defeat both Kaecilius and the Dread Dormammu. He did so by turning back the clock, and rewriting history.

The same film saw Strange warned about the Time Stone’s power in no uncertain terms. Those warnings make even more sense in light of Agents of S.H.I.E.L.D.‘s model of time travel. The Infinity Stone’s power is so vast that it can literally rewrite the nature of spacetime itself. But how many times can spacetime be rewritten before something breaks? As Mordo warned, there’s always a price to be paid. That’s true even for the immeasurable power of an Infinity Stone.

Meanwhile, establishing the normal nature of spacetime simply makes Strange’s feat all the more staggering. The final battle between Strange and Dormammu literally sees the future Sorcerer Supreme breaking the laws of time and space. His victory is all the more remarkable.

What does this mean for the future of the MCU?

So far, the MCU has wisely avoided plots focused on time travel. The danger is that it becomes a deus ex machina, with sloppy writing using time travel to reboot reality or avert a defeat. Some Marvel fans are already suggesting that the Time Stone could be used to resurrect Yondu, or to repair Mjolnir. If used poorly, time travel simply becomes a way to undo the consequences of a scene.

By committing to this model of time travel, Marvel is ensuring the idea can’t be used in that kind of way. Only the most powerful objects can be used to change time, and for all we know the Time Stone will ultimately be taken off the table. Meanwhile, the House of Ideas has left themselves open to some intriguing plots. Imagine, for instance, a Young Avengers plot in which Iron Lad is attempting to avert his future as Kang the Conqueror. Because of this model of time travel, we’d know all along that he would be destined to fail. You can get real dramatic mileage out of the idea of a hero desperately attempting to prevent a future that simply has to be.

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So now we know how time travel works in the Marvel Cinematic Universe, and we’re definitely not in the world of Doctor Who. In the MCU, the past is fixed, and any future we experienced becomes fixed as well. Our heroes can try all they want to change that, but they’ll be doomed to failure. Unless they have the Time Stone to hand, of course.