WARNING: The following contains major spoilers for The Tomorrow War, now available on Amazon Prime.

Amazon Prime Video's The Tomorrow War is the latest in a long line of sci-fi films that heavily rely on time travel as a plot device. In the Chris Pratt-starring film, people from the year 2023 are drafted to travel to 2051 and fight a war against an army of alien invaders called the White Spikes. The film's time travel relies on a piece of technology called the Jump-Link, which transports large numbers of recruits to the future for seven days at a time before bringing them back. Here's an explanation of how time travel works in The Tomorrow War, paradoxes and all.

Tomorrow War Chris Pratt Helicopter

Early in The Tomorrow War, Dan Forester (Pratt) is drafted to join the war and is fitted with an armband. At a military briefing, Forester and the rest of the recruits are informed of the Jump-Link, which is an experimental time travel device connected to each of the recruits' armbands. Using the metaphor of time flowing in one direction like a river, the soldiers explain that the Jump-Link essentially places two rafts on the river, almost 30 years apart from each other. The characters cannot travel to any time other than the present day and 2051, preventing them from traveling to the early stages of the war and overwhelming the White Spikes then.

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It is later revealed that the recruits are all people who are dead by 2051, while the soldiers training them in 2022 all haven't been born yet. The reason for this is to avoid a time paradox - none of the recruits will run into their future selves and none of the soldiers will run into their past selves.

Something that differentiates the Jump-Link from other time travel devices is that it can transport large numbers of people at a time. When Forester and the rest of the recruits are sent forward to the future, they must all stand in rows within a large room. The soldiers then turn on the Jump-Link device and open a portal, informing the recruits that the Jump-Link is designed to drop them five to ten feet above the ground on the other side. The recruits then get sucked into the portal row by row.

Exactly seven days later, the Jump-Link returns Forester and the rest of the recruits to 2023. No matter where they are or what they are doing, they are sucked upwards into a portal and disappear, popping back to their proper time period five to ten feet off the ground. It is possible to go through the portals more than once, as Forester's fellow soldier Dorian (Edwin Hodge) is on his third time going through the Jump-Link. The White Spikes end up destroying the Jump-Link in 2051, preventing the characters from returning to the future.

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How The Tomorrow War's Time Travel Creates Paradoxes & Other Pitfalls

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As to be expected when it comes to time travel logic, there are some inconsistencies and drawbacks with The Tomorrow War's Jump-Link. One of the main issues with the Jump-Link is the fact that it drops the soldiers several feet off the ground. While there is a potential for injuries from the fall (as demonstrated when Forester and the recruits return to 2023 and make some hard landings), the bigger problem is that people can end up dropping from much higher if there is a problem with the output coordinates. This happens to Forester and his fellow recruits, and they end up dropping from rooftop-level in the middle of the city. While Forester manages to land in a swimming pool, several of his comrades are not so lucky and fall to their deaths.

Another major inconsistency with the Jump-Link comes from the fact that the soldiers return to 2023 at all. Them being allowed to come back from the future with all their memories and knowledge from the war in place creates a huge opportunity for a time paradox. Even the soldiers initially traveling back to 2023 to establish contact at all seems pretty risky, considering they completely changed the timeline by informing the world about the future war. The Tomorrow War's soldiers are very lucky that their meddling with time didn't end up bringing about the world's destruction before the aliens did.

Starring Chris Pratt, Yvonne Strahovski, Sam Richardson, Betty Gilpin, J.K. Simmons and Edwin Hodge, The Tomorrow War is now available on Amazon Prime.

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