The concept of time travel has long been a popular theme in fiction and film. Traveling back in time to alter the course of history is an alluring idea that has enthralled not just fiction writers but scientists as well. Yet, if you've ever seen or read a time travel story, you're aware that time travel is a tricky concept to grasp. It might be challenging to stay faithful to your worldbuilding concepts while simultaneously incorporating suitable temporal paradoxes.
For this reason, we will explore different paradoxes and go through various tips to help you write a time travel story without the risk of paradoxes.
Where does the idea of time travel come from?
Traveling across time is a shared universal dream. But where did the fascination with time travel begin, and why does the concept appeal to so many people? The lure of time travel has deeper origins. Appearing in some of our oldest stories, it is woven into the very fabric of our language and imagines a world without constraints of time and space. Its roots may be traced back to ancient tales of time travel found in numerous civilizations throughout the world, giving the notion its distinct characteristics derived from different cultures.
We come across time travel stories in ancient cultures throughout the world, although we cannot claim to know where the concept originally came from and who pioneered it. However, we can observe that the genre rose to prominence in the nineteenth century. From this time period comes Charles Dickens' classic novella A Christmas Carol, in which Ebenezer Scrooge travels both ahead and backwards in time. Around the same period, H.G. Wells popularized time travel in literature with his timeless novel The Time Machine, which featured the concept of a "time machine," which featured a vehicle that could travel purposefully and selectively in time. Inspired by this emblematic icon, many beloved time-travel stories published after this have incorporated some form of the time machine. Such is the famous TARDIS in the long-running BBC classic series Doctor Who, a blue box that can transcend time and space. Doctor who interestingly explores time travel paradoxes, with time paradoxes taking a center stage for many of its episodes.
Time travel paradoxes
There are many logical contradictions when it comes to time travel. Here are some of the major paradoxes:
Bootstrap paradox
The Bootstrap Paradox is a theoretical paradox of time travel that arises when an object transported back in time becomes locked within an unending cause-effect loop. This occurs as the travel in time takes place as a response to a specific event.
Consistency paradox
Consistency Paradoxes, such as the Grandfather Paradox, or the Hitler paradox, a type of timeline mismatch that arises from the prospect of changing the past. These paradoxes change history in such a way that time travel into the past, which caused such action in the first place, is no longer possible. To simply illustrate the paradox, in the film The Time Machine, a protagonist builds a time machine to travel back in time in order to save his fiancé from death. Her rescue, on the other hand, would lead to a future in which the machine never existed since her death was the direct motivation for its creation. But then, how is it you can go back and save your fiancé if her death hasn't given you the push to create the time machine? It results in a paradox. The timeline is no longer self-consistent.
Butterfly effect
The Butterfly Effect is based on Chaos Theory, which states that seemingly minor changes may have massive cascade responses over extended periods of time and that even minor changes can fundamentally reshape history. The name "Butterfly Effect" originates from Ray Bradbury's short tale "A Sound of Thunder," in which a character in prehistoric times walks on a butterfly, causing massive changes in the future.
How to avoid these paradoxes
The self-healing hypothesis
Writers seeking to escape the paradoxes of time travel have devised a variety of inventive methods for presenting a more consistent picture of reality. The self-healing hypothesis is one of the most basic solutions to any time travel paradox, implying that no matter what is changed in the timeline, the principles of quantum physics will self-correct to prevent a contradiction from arising and sustain the existing flow.
Because events would adapt themselves, a paradox would not occur. So, changing the past will trigger another alternative chain reaction that will keep the present unaltered. This effectively states that the likelihood of a paradox arising in any given circumstance is zero. The self-healing hypothesis simply indicates that no matter what a traveler has done in the past, the end outcome is the same in terms of global conditions. This does not rule out the possibility of changing the past, but it does eliminate the prospect of minor changes having the power to generate massive ones. Most crucially, as an author, you are not obligated to describe the particular events that repair time. It is enough to affirm that they take place and ensure that your event sequences and their conclusion are consistent.
Time traveling monitor
Another way to avoid temporal paradox would be creating the time traveling monitor that would follow the timeline protection hypothesis, which posits that any attempt to create a paradox would fail to owe to a probability distortion. The monitor would adjust the probability in order to avert any damaging events occurring, which would also give you free rein to come up with creative scenarios. Nonetheless, to prevent an impossible event from taking place, the universe must favor an improbable event occurring.
Balancing the timeline
The paradoxes themselves are intertwined and they can as well occur simultaneously. No one knows if a real-life paradox would result in a large-scale timeline alteration, or if the closed-loop is kind of automatically self-correcting since everything works out equally in the end. Going back to the Consistency Paradox, yet another approach to avoid it is to acknowledge, regretfully, that you can't and shouldn't attempt to change the past. That is unless you can rule out any chance of a bad domino effect as a result of your activities. In this manner, you can attempt to alter the past while keeping the chronology intact. This means following up the time-change event with another change that balances out the activities and ensures that the outcome remains the same despite the intervention.
Time loop
The notion of a time loop is one of the most prevalent strategies to get away with time travel in science fiction. You may travel through time here, but any changes you make are predetermined. For example, suppose you were pushed out of the way of a car one day. You return to your timeline from the future and realize that that person was in reality you.
Paradoxes are avoided with this method of time travel, but everything is predetermined. If you wish to prevent a tragic incident from occurring in your past, there's nothing you can do since even if you could, it would still happen in the time loop. Whatever you did, the key events would just re-calibrate around you. This could be the solution for the Grandfather Paradox — that would mean that the event propelling you back in time would happen regardless of your actions, providing your younger self with the incentive to go back and stop it. To put it another way, a time traveler could make adjustments, but the original conclusion would still occur — perhaps not exactly as it did in the initial timeline, but near enough.
Parallel universe
There is also another possibility: creating a parallel universe. The future or past you visit might become a parallel reality. Consider it as a huge fortress where you may construct or demolish as many castles as you like, but it has no bearing on your primal stronghold. When you travel back in time, the future is gone, it never happened, and the universe will evolve anew, even if you do nothing to influence it. It does not affect the future you experienced, but it does affect the future of the reset world. That can entail creating a scenario in which the protagonists travel to the past and discover themselves in a parallel world or multiverse, with no change to their original chronology.
Countless science fiction stories have examined the conundrum of what would happen if you could travel back in time and do something that would jeopardize the future. Please note that you are free to make your own rules for it. This is your work of fiction. The universe will be as you will design it in your story. If the paradoxes do not exist in your story, then you may make up your own rules around it. You can as well bypass the rules your worldbuilding has established if you have a valid cause for doing so and if this is what your writing demands.