Hello, travellers, and welcome to Recorded Tomorrow, the show where we break down the rules & pitfalls of using time travel in fiction & games. Jonathan is caught in a temporal rift, so I’ll be navigating the timestream solo today.
Rather than try to tackle a deep dive by myself, I thought I’d take this opportunity to recap the lessons we’ve covered so far, & consolidate them all in one place. I’ll go over the rules we’ve established & define all the terms we’ve used. I’ll jump around a bit, but hopefully I’ll do it in a way that makes sense. Right, let’s get straight to it:
A traveler isn’t necessarily a person, but refers to anything that’s being sent through time. That could mean a person, or their consciousness, a device, even just information. We might sometimes refer to this as the subject.
The origin is the time and place from which the traveler departs, and the destination is the time & place when they arrive.
Now let’s talk theories: Variable Thread is typically a single, mutable timeline of continuity that can be altered using time travel. In fiction that uses variable thread, as soon as someone or something travels to the past, the timeline resets from the point of arrival, and the original timeline ceases to exist. This is the most common style of explicit time travel. Think Back to the Future or The Sound of Thunder. These types of stories are usually a regret metaphor.
Fixed Thread is an immutable timeline, where the continuity can’t be changed, even by traveling back in time. Any actions taken by a traveler happened before they traveled, the only thing that changes is the perspective. This is your Bill & Ted, your 12 Monkeys, your Prisoner of Azkaban. These stories are generally about trying to be in multiple places at once, taking on too much, and learning to prioritize.
Lastly, we have Multiverse time travel. This theory involves multiple, timelines, and can come in a couple of forms: in Michael Creighton’s Timeline, the characters don’t actually travel forward or backward in time, but rather laterally into older or younger universes; In Avengers: Endgame, characters do travel through time, but each time they do, it creates a new branch on an existing timeline.
These are the basics. There are variations, like river theory or using flashbacks, but they pretty much all build on these three.
Regardless of which theory you employ, there are a few guidelines you should always keep in mind.
The single most important rule is to Be Consistent. It doesn’t matter what the time travel rules are in your universe, as long as you know them, and you make sure you always, always follow them. Be consistent. Be consistent. Be consistent.
In order to stay consistent, you’re going to need to take notes. Copious, copious notes. If you're traveling to real historical times & places, do your research and get it right. Even if you're in a fictional universe, remember that everything your characters do could be important. Everything they say, anyone they interact with, could cause rippling changes, and the further back the travel, the larger those changes can be. If you're dealing with interactive fiction - like a role-playing game - it's probably a good idea to record your sessions.
Forgive the pun, but you’ll also want to be sure you take your time with your story. Any time a character or characters travel through time (either forward or backward), stop and check your notes. Make sure you've got everything lined up, extrapolate answers to questions, figure out as many ramifications to changes made as possible.
- If you're writing a novel, end the chapter or section here.
- If you're writing a screenplay for a film, use this as a scene- or act-break.
- If it's a TV show, go to commercial.
- If it's interactive fiction, end the session there.
Now, I said you have know the rules of time travel, but that doesn’t mean your characters have to. 12 Monkeys executes this brilliantly, with Cole traveling back in time to try and change his future, only to find out that he’d seen his older self there as a child. The characters all believed they were in a variable thread universe, when in fact their universe was fixed thread.
Everything I’ve mentioned so far apply equally regardless of how time travel works in your story. Let’s dive into some theory-specific guidelines. We’ll start with VariableThread:
The one thing most Variable Thread stories forget is something we’re calling The Outsider Problem. When a traveler arrives at their destination, every part of their original timeline is erased (usually immediately, but that can vary from story to story), except the traveler themselves. They become an Outsider, and no longer belong in any timeline, because even when they return to their origin point, it will be in an alternate timeline with another version of the traveler. Basically, with Variable Thread, once you travel back in time, there will always be two of you, and you’re the one who doesn’t belong anymore.
This manifests a little differently when traveling to the future: rather than traveling to a destination where there will be another version of you, you’re traveling to a future where you’ve been absent since the moment you left. If you travel to ten years in the future, you’ll arrive to a world where you’ve been missing for ten years.
Bottom line, if you’re using Variable Thread time travel, you’ll need to either embrace the Outsider Problem, or mitigate it somehow. One of the most common methods of mitigation is to only send a consciousness backward or forward in time, rather than a physical human. The arriving consciousness either supplants, suppresses, or merges with the existing one, so there is no Outsider.
Fixed Thread is a bit trickier, in that there are a number of extra pitfalls to watch out for. But first, I have to reiterate rule #1: BE CONSISTENT. Consistency is especially important in a Fixed Thread story, because you’ll likely be describing the same scene more than once, from different perspectives. When that happens, it’s imperative that your events and dialog line up. Because the timeline is immutable, you can’t change the way a conversation plays out, or the order in which events occur. On a related note, be sure to sprinkle bits of foreshadowing into your narrative, so your audience will have a thread to connect events between perspectives (though that’s just generally good fiction advice, so I probably don’t need to mention it).
The Outsider Problem doesn’t exist with Fixed Thread or multiverse time travel, but you do have to remember and account for the fact that your traveler will continue to age when they travel through time. This means that when they return to their origin they’ll be older than they were when they left. Realistically, after a year of time-traveling back to repeat every school day, Hermione would be over two months older than Harry and Ron.
And, finally, we need to tackle Paradoxes. A paradox is an event that alters the timeline in such a way as to create a contradiction of events, and the truth is that if you’re consistent and follow the rest of the guidelines above, paradoxes aren’t actually a problem.
To illustrate that, let’s take a look at the classic example: The Grandfather Paradox. The idea is that if a person were to travel back in time and murder their grandfather before they had any children, then the traveler themselves would never have been born, which means they would never have been able to travel back in time to murder their grandfather.
Except it’s garbage.
Let’s examine the three theories in each scenario: In Variable Thread, the traveler is an Outsider. Murdering their grandfather would succeed in preventing their birth, but it’s not the same version of them as the one who traveled back in time. The traveler will continue to exist in a timeline that they’re not actually a part of, in which no version of them is ever born. No Paradox.
This applies to Multiverse time travel, as well: You could quite easily prevent yourself from being born, but it’d be in an alternate timeline, which would have no effect on the one from which you traveled. No Paradox.
In a Fixed Thread the fact that the traveler exists means they would be physically unable to prevent their birth. They could try to murder their grandfather, but they would fail. End of story. The thread is fixed and can’t be changed. No Paradox.
Fixed Thread does have something that’s pretty close to a paradox, though, and that’s a Causal Loop. We defined a Causal Loop as a self-manifesting concept in which the something (be it information, an object, or even a person) sets in motion the events that result in its own creation.
My go-to example is the directions out of a maze: If a person is stuck in a maze and finds a map leading out, then after they get out, they travel back in time and places the map back where they found it, where did the map originally come from? The answer seems to be “from nowhere.” Causal Loops don’t actually break any time travel rules, but they’ll still pull people out of your story unless they’re handled very carefully. Unless they play a major role in your story, I’d avoid them altogether. There exists a wonderful example of a story that is built entirely on Causal Loops, but I won’t say what it is because I don’t want to spoil it.
Finally, it’s vital to remember that, regardless of the mechanics, a time travel story is a story first. Every time-travel decision should be in service to the story. I’m skipping ahead a little because some of this will be covered in future episodes, but you’ll want to start with figuring out what kind of story you want to tell, then choose a complimentary time travel theory. Conversely, if you want to use a specific theory, make sure your narrative themes compliment that theory. You’ll want to choose a mode of travel - such as a time machine, device, portal, etc.. - based on the types of complications you want to introduce.
And that brings us back to the present! Pretty much everything we’ve covered on the show so far, condensed into half an hour. If you’re new to our show and want to hear Jonathan and me dig deeper into any of these subjects, they’re all in the archives. If you’ve been with us from the beginning and want to introduce the show to your friends, this might not be a bad place to start.
But there’s one more thing I want to talk to you about: We’ve got a few more episodes planned, but we’re approaching a point where we’re going to run out of basic lessons. There are a few subjects we want to dive deeper into, but after that, we’re going to have to pivot, and change the nature of the show somewhat.
And that’s where you come in. Once the basics are covered, what would you like to hear from us? We could do analyses of time travel in specific works of fiction (similar to what we did with Avengers: Endgame). We could turn it into more of a question & answer show, where listeners send us questions or issues they have and we try to answer them. We could even put our money where our mouths are, and try to craft a time travel story together with you listening in. Let us know what you’d like to hear on twitter at @TimeTravelPod, or via email at firstname.lastname@example.org. Thanks to Kevin MacLoed of Incompetech for our theme music.
Special thanks to Greg Downing, Cal O'Boyle, & Ariel & Connor Ferguson for lending their voices to my desperate need for consistency.