Time travel is an old fantasy that has captured the imagination of many artists. 7e art has obviously taken hold and delivered inspired works that have left their mark on generations of spectators. Still today, many films and series play with this notion to make us travel through the ages… And sometimes we get lost in it! Three theories concerning these temporal excursions stand out and federate a large part of the science-fiction feature films of the last decades. Here is a little summary to help you see more clearly.
This is one of the most widely used theories in cinema. And in many ways, it seems more realistic and natural to us. It states that altering the events of the past will have a definitive impact on the present that one has left. Scenarically speaking, it opens the door to many ideas since it materializes a dream that everyone has already made: to go back and make the right choice. Moreover it adapts to many film genres: drama, romance, comedy… Everything is possible.
It thus offers the possibility of eliminating a threat upstream so as not to be worried when returning to the present, or to make the right choice for success or love.
It can nevertheless lead to an astonishing, even dangerous paradox for the main character. Often referred to as “the grandfather paradox”, he suggests that this use of the time curve can be problematic with a simple example. If I kill my grandfather before he had children, I couldn’t be born. But how could I have made the trip to assassinate him? Several answers can be given to this paradox, notably by using the notion of the time loop, but it still fascinates many amateurs.
This theory was Robert Zemeckis’s forte as it alone laid the foundations for the cult saga Back to the Future. Young Marty McFly will never stop travelling back in time with Dr. Emmett Brown to solve time paradoxes caused by his own interventions! And for a good example from home, we can also mention The Visitors. In Jean-Marie Poiré’s film, Godefroy de Montmirail mistakenly kills his future father-in-law, which prevents him from marrying Frénégonde. Accompanied by his faithful squire (not very well prepared, of course, but sniffing well the tracks) he will drink a potion to come back a few moments before the drama… Even if it means getting lost in the corridors of time!
Time travel on a fixed timeline is based on a simple premise: The future can’t really be changed or modified. This theory is partly based on Novikov’s principle of coherence, developed in the 1980s. The latter stipulates that there is only one timeline and that it cannot multiply.
Even though people could travel to the past, the future they have left behind cannot be changed. Their actions in the past are already part of history. Getting rid of a bloodthirsty dictator while still a child (and/or replacing him with another toddler) will not affect his existence since the child being replaced (or even another one) will become a dictator in his place. Although more pessimistic, this theory remains quite fascinating since it does not expose itself to a paradox like that of the dynamic timeline.
(Attention, spoilers on old movies are below)
Probably the most convincing cinematic example is the Terminator saga. In the first opus, a super-powered robot is sent to the past to kill Sarah Connor’s son (John) because the latter will later become the leader of the human resistance in the war against them.
We realize, however, that if he had succeeded in his mission, another man would have taken John Connor’s place at the head of the human troops. The famous sequel shows how John, Sarah and the T-800 destroy Cyberdyne and yet…The Doomsdaystill takes place in the third episode. This vision close to the Abrahamic religions suggests that man cannot escape his destiny.
The third theory is based on the “multiverse” principle and leaves even more room for imagination. It detaches the time traveler from his fixed or dynamic timeline, since the latter literally changes universe. He thus finds another version (old or futuristic) of himself… Unless he has already died in this one! Depending on the works, his alter egos will resemble him perfectly or will have taken a totally different path.
In a parallel timeline, the traveler can do literally what he wants since only the new timeline will be affected. If you decide to kill all your forefathers in the latter, it will not create any paradox. Just a new story in which you’ll never exist.
Screenwriters like to use quantum physics to bring realism to these journeys through space/time. This was the case in Christopher Nolan’s Interstellar but also in the excellent episode “A Rickle in time” of the series Rick & Morty.
The superb animated film Spider Man: New Generation also cultivates this idea. It tells the story of Miles Morales, an African-American teenager turned Spider-Man after being bitten by a spider. Using a particle accelerator, his enemy opens portals to other universes, where a flock of other Spider-Man will emerge. An old Peter Parker, Spider-Gwen, Spider-Cochon and even a manga version will then meet.
How not to mention the recent Avengers: Endgame, which continues to break records since its release? We’ve put together a special folder for the occasion to help you see more clearly.
In the latter, the remaining Avengers go back to the past in search of the gems of infinity, opening the door to a new timeline (without the stone of time). If by chance the Hulk of the present had killed the Hulk of the past, he would not have disappeared, he would have simply created a dimension where he died. However, the treatment of Captain America’s character challenges the time travel theory adopted by the Russo brothers according to some fans…
A short excerpt from the upcoming Spider-Man: Far From Home shows a dialogue between Peter Parker and Quentin Beck, alias Mysterio. He explains that he does not come from the same Earth (he would come from 833 and Peter from 616) but that their two planets “share identical physical constants”. It remains to be seen whether he’s telling the truth.
These few theories are already making our minds wander, but there are many more. Which one do you think is more realistic?