I've got quite a busy week on this week, and the movie I wanted to blog about isn't actually out yet. So this week I'm posting something that has nothing to do with apocalypses of any kind. This was a talk I gave at a conference at the University of East Anglia a couple of years ago. So, here's my guide to writing time travel so that you don't end up with any of those annoying paradoxes.
Working the Time Machine: Writing Time Travel So It Makes Sense
When H.G Wells first conceived of the Time Machine, it must have seemed like a fairly simple conceit. If you have a character in the present day, and you want him to have an adventure with dinosaurs, or medieval knights, or futuristic robots with laser guns for hands, have him hop into the time machine and it will take him where, or when, you want him to go. These stories are usually very straightforward, the past is almost literally another country.
But it wasn't long before writers worked out that you could influence events in this other country, and by extension, alter the nature of the present. Puzzlingly, a lot of the time, the first thing people wanted to change was that their own grandfathers had never been shot. I don't know why this is, personally I like my grandfather, but once you open up that option, time travel has some mind-boggling implications. If your grandfather dies before your mother or father is conceived, they won't be born, so you won't be born, so just who's going to shoot your grandad?
 |
| Because fuck that guy |
For the writer, there's clearly the potential for some good storytelling here. But from the get go you've also got some major problems. One thing causing another is pretty much the simplest definition of a story you can get. If you start mucking about with that, you better know what you're doing, because events can get tangled up in themselves, very quickly.
That's what this talk is going to be about. If you're writing a story about time travel there are various models you can use to explain how cause and effect work, and we're going to go through them. We will look at the restrictions these models place on the writer, the options they give, and the loopholes they create.
What Happens, Stays Happened
Let's start with what might be the simplest model of cause and effect. What happens, stays happened. You can't change history.
 |
| No matter how good an idea that might be |
You take your DeLorean back in time, try to shoot your granddad, but you miss. You try again, but the gun jams. You get a new gun, shoot him in the head at point blank range, and it turns out he wasn't your real granddad, and if you'd asked your grandma before you set out, she would have told you that that was the way he'd always died.
This is a popular model, a lot of scientists are big fans of this model, less for any scientific reason than because of a vague feeling that anything else would just get silly. They may be right, but I intend to show they've vastly underestimated people's potential for silliness.
Often this rule will be taken even further, and someone trying to change the future will inadvertently cause the thing they wanted to prevent. You try to kill your granddad, but some hilarious slapstick sequence of events mean you actually save his life.
This is an old plot, you can date it back to before Oedipus's dad had his son left on a mountainside because he'd heard that when the kid grew up bad things would happen. This is far from the last reference to Oedipus in this paper.
 |
| Why do all my blogs end this way? |
For the writer, this model of time travel can work nicely. As I said earlier, what happens, stays happened, you don't have to worry about things your character does in Chapter Twelve wiping out what they did in Chapter Three. Actions have consequences, and those consequences are permanent. There's no hope of a quick fix when your character goes back to alter history to suit themselves.
At the same time, although your story can't go back and negate itself, there is still a lot of room for plots to loop back on themselves, and often the story you end up with will be far from linear. If you're going to attempt this sort of story, it's a good idea to be good at plotting. Often, these stories will end up following the structure of a detective story, starting at the end, and spending the narrative working out how the protagonist gets there, but this is just the simplest structure this sort of story can take.
An excellent example of the use of this sort of time travel can be found in The Time Traveller's Wife.
 |
| You know, I didn't know how creepy this paper's underlying themes were until I started illustrating it |
For those of you who haven't read the book or seen the movie, the Time Traveller in question is Henry DeTamble, a man who frequently finds himself hopping backwards and forwards through time, with no control over where or when he will end up, or for that matter, any clothes when he gets there. A lot of time travel seems to involve nudity. I don't know why.
 |
| Also, everyone seems to come out of time travel looking ripped |
The story switches between being narrated by Henry, and his wife Clare. Henry meets Clare when he is twenty-eight and she is twenty. Clare meets Henry when she is six and Henry is thirty-six. They both experience exactly the same events, but in a different order. They also have to deal with the knowledge that their future is set and immutable. Henry regularly travels back to events in his own past he would want to change – his mother's death in a car crash, an accident he sees at the ice-rink, and the time his father walks in on him as a teenager making out with his future self. He is powerless to prevent these things from happening.
But this doesn't render Henry and Clare completely powerless. It doesn't stop them from being able to win the lottery, should they ever want to. It doesn't stop them from using information about a doctor's unborn child to manipulate him into taking on Henry's case. And it doesn't stop Henry from giving six year old Clare a list of dates, telling her exactly when and where his trips through time will bring him to her.
We'll come back to these tricks in a second, and see just what we can do to push them to breaking point, but before we start getting pleased with how clever we are, I'd just like to point out what the time travel manages to do for the part of the story we're actually supposed to care about, the relationship between Henry and Clare.
For a start, we get to see Henry and Clare's relationship from several different angles. Every time Henry and Clare meet they are different ages, knowledge of the past and future is divided up differently between them, and this affects the way the relationship works. For Clare, Henry goes from being a cross between a parental figure and an imaginary friend, to a teenage fantasy, until eventually he becomes Clare's life partner. On the other hand, when Henry meets Clare for the first time, she's a complete stranger who already knows a large part of Henry's future before he does.
The other notable use time travel has in this story, is something sci-fi has always been very good at, taking a metaphor and taking it absolutely literally. A relationship is full of metaphorical time travel, you spend a lot of it in your imagined future, with the fantasies, hopes and fears that accompany that. Equally, nostalgia, grief and regret can draw you to the past. For Henry and Clare, this isn't just flowery language, it's a physical truth.
Which is all very touching, but we're not here to talk about love stories, we're here to screw up the laws of causality, so let's focus on one of the tricks this book pulls off- going back and doing favours for yourself in the past. If you remember your future self helping you out before, you're not changing history, you're just completing a loop. Once you allow for that, we can really start to enjoy ourselves.
My personal favourite example of this trick is in Bill & Ted's Bogus Journey, probably the third greatest film about evil robots from the future ever made. The Bill & Ted movies follow the adventures of the Wyld Stallyns [sic], who will eventually become the greatest rock band who ever lived, saving the environment, bringing about world peace, and making the air guitar the standard form of greeting.
 |
| These films were so good, Keanu Reeves decided to never act again |
At the climax to the second film, Bill and Ted face off against the villain who has come back in time to destroy them. It seems that Bill and Ted are doomed, until Bill comes up with a fool proof plan:
“After we get away from this guy, we use the [time machine]. We time travel back to before the concert and set up the things we need to get him now.”
At that point, it turns out a sandbag and cage have been set up to drop from the ceiling, disarming the bad guy and trapping him. The bad guy's response to this is to point out that when he has defeated Bill and Ted, he's going to go back in time and equip himself with the key to the cage and a spare gun, promptly, it turns out he has both those items. Only for it to turn out that the gun is a dud because "Only the winners are going to be able to go back and set things up!" Bill and Ted set up the key and fake gun for kicks.
Despite appearances, at no point is time changed. Bill and Ted had always gone back in time after defeating the bad guy, and the cage had always been hanging in position, waiting for the right time to drop down.
Okay, so let's see if we can push this even further to breaking point with another, entirely hypothetical example.
Supposing, just supposing, that instead of spending the last few weeks studiously researching and preparing this paper, I instead spend the last few weeks playing Halo 3 and watching reruns of The Gilmore Girls. When today comes round, somehow I sleep in until three in the afternoon, and only just have time to get to campus. We've all been there.
 |
| It's like a hug for your eyes! |
Luckily, as I'm on my way out of the house, I find an envelope on the doormat. I look outside, but there's no-one there, just a couple of flaming tire tracks and a number plate spinning in the road. The envelope, rather handily, contains this very paper. I deliver the paper, and it's a huge success, then slip I out of the building, climb into my DeLorean (did I mention I have a DeLorean?) and travel back in time to this morning. I put the paper in an envelope, push it through my own letterbox, then hop back in the car and disappear.
 |
| Then I use my DeLorean to pick up chicks, because Relativity says the DeLorean is the sexiest of cars |
Again, this series of events is entirely consistent with itself, past present and future form a neat little mobius strip. But I'm sure some of you are wondering, if that's the case, who actually wrote my paper?
Well, until anyone else steps forward, I'm still going to take the credit.
Robert Heinlein was a big fan of this sort of loop, and pushed it about as far as you possibly can with his story All You Zombies. In that story, a girl grows up in an orphanage, is impregnated by a mysterious stranger, who later turns out to be her transexual future self. The transexual future self then steals the baby, takes it back in time, and drops it off at the orphanage. The girl is her own mother and father, begging all sorts of questions. I told you that wasn't the last Oedipus reference, didn't I?
There are all kinds of tricks and paradoxes you can pull without altering so much as a second of history. However, handled poorly, the unchangeable history has its own pitfalls.
For a start, it can lead to your characters having to behave unnaturally just to keep the plot consistent with itself.
I think it's fair to say that a lot of people, finding themselves in the past, would try to alter history just to see what happened, even if they didn't have a motive for doing so. We're just spiteful like that. If the writer acknowledges that, they will often find themselves creating ever more contrived sets of circumstances and coincidences to keep time on the correct path. You can only keep this up for so long before it begins to stink of deus ex machina, and maybe even end up with people talking about “Time” as an anthropomorphic entity, which I've always felt borders on cheating.
 |
| Plus, let's face it, the laws of causality would have to work pretty hard to keep this guy alive |
But what if you can change history?
“The future is not set.”
That's a quote from The Terminator, a film that, at first glance seems to follow the standard plot of “go back in time, try to prevent something, inadvertently cause it to happen.” Arnold Swarzenegger goes back in time to prevent John Connor from ever being born, and in the process, accidentally introduces Sarah Connor to John's father. There are even deleted scenes to show how the mangled remains of the Terminator end up inspiring the creation of the computer that will eventually become Skynet and kill us all. It seems like a perfect loop.
But in the first film, James Cameron keeps dropping hints that history can be changed. There's the above quote, from John Connor of the future, there's Kyle Reese insisting that he's from “one possible future”
Then, in the second film, John, Sarah and another Terminator track down the man responsible for building Skynet, blow up all the information relating to it and prevent Skynet from ever coming into being. From a storytelling point of view, this serves several purposes. It handily explains why we didn't all die in a nuclear holocaust in 1997. It allows John and Sarah Connor to have a happy ending, which they couldn't have had if the future was set . And it means we can all pretend Terminator's 3 and 4 never happened.
 |
| Wiped from history |
For those of you keeping count, Terminators 1 and 2 are the second and first best evil time travelling robot films ever made, and two more examples of time travelling nudity.
Now, in the name of full disclosure I should point out here that I prefer this sort of story. I feel like the stakes are higher if the future is changeable, and it’s easier to become invested in characters who can take full credit or blame for their actions. Of course, having said that, I should point out that if history is changeable, that doesn't automatically imply free will exists. It could just mean determinism is really badly organised.
A Matter of Perspective
Writing a time travel story with a changeable history does give you a lot of options, but it also confronts you with a brand new set of problems. Perspective, for example, now has to be a much more precise tool. If you can't change history, you can view the story from any angle you like, the actual events will always be the same. If history is changing, that isn't the case.
The easiest solution is to keep your perspective nailed to your time traveller. After all, your time traveller is likely to be the only person to actually notice history changing, so they will probably be in the best position to watch events. They will know how history has changed, what history was like before, and what caused it to change.
Another solution is to place your perspective with a character from the past that's being travelled back to – this is pretty much how the Terminator films work. Again, this is reasonably straightforward. You don't see history changing, you only see events unfold, and how the time traveller is influencing them. The time traveller might explain how history originally unfolded, and you might be able to guess at how things would have turned out if the time traveller wasn't there, but for all intents and purposes you only see the one version of events.
The other alternative is a lot more tricky, and that is to tell the story from the perspective of the future that is being altered. If you're going to do this, you've obviously set yourself quite the challenge, as character's memories will be changing from one scene to another and the reader will often be the only one who can see what's really going on. If you're going to write your time travel story this way, you're going to have be very good at getting information to the reader subtly, and often you'll have to depend on them to fill in the blanks for you.
Of course, it's possible to switch between these perspectives, but if you do you will risk confusing your reader for the sheer hell of it.
Photoshopping Through Time
Regardless of what point of view you're watching from when history gets changed, we're still back at our original question – what's going to happen when you shoot granddad?
One option is you shoot your granddad, and then mysteriously fade away as you've erased yourself from history.
Many of you will remember this version of cause and effect from that other great example of an Oedipal time travel plot, Back to the Future. For those of you who haven't seen this masterpiece of modern cinema, Marty McFly travels back to 1955, and accidentally disrupts his parents' first meeting, causing his teenage mother to develop a crush on him, and negating his own existence.
 |
| Having sex with Lea Thompson is widely considered one of the better ways to negate your own existence |
We know he's negated his own existence, because on a photograph he's brought from the future he can see his older siblings fading away, one by one, until eventually his guitar playing hand also begins to disappear.
 |
| Changing the fabric of causality is just slightly less efficient than using photoshop |
Now if we're going to start picking holes in the logic here, there are rich pickings, and that's without even touching the sequels. For starters, you have to wonder what George McFly thought when his third born child came out looking exactly like the guy his wife used to fancy in High School.
 |
| It's telling that an earlier timeline, Marty McFly looked more like Eric Stoltz |
But aside from that, the biggest problem with the fadey-photograph method of showing how history changes is that when Marty changes something in 1955, it seems to change in 1985 at the same time. You can get this problem quite often when writers think of the past as literally another country. You can trace this right back to H.G. Wells' Time Machine, when his narrator suggests that “even now” the Time Traveller is on some “on some plesiosaurus-haunted [...] coral reef.”
We're going to give Back to the Future some slack here though, and not just because nobody has yet designed a time machine that looks cooler than the DeLorean. Back to the Future is, as the title suggests, ostensibly about Marty trying to return to a time period that hasn't happened yet. Since the plot demands he have some difficulty doing that, he can't keep nipping forward thirty years to see how his actions have affected 1985. Even if he could, it would make for a fairly unwieldy plot. The fading photographs give the audience a shorthand for how events are going to play out.
And despite the title of the film, the central pillar of Back to the Future's plot isn't Marty's attempt to get home. The main story arc is arguably George McFly's. The film is the story of a wimp's struggle to get the courage to stand up to the bully and ask out the girl. Marty is there partly as a catalyst for setting events in motion, and partly to raise the stakes, and make George McFly's teenage concerns a matter of a life and death (or at least, life and not life).
Branching Out
Still, if you want to have a time travel story where history is mutable but your plot still stays internally consistent and there's no “meanwhile, in the future” nonsense, we can do that too. The way we do this, is quite simply, to cheat.
So, let's get our gun, climb into our DeLorean and head back in time to a nice little cafe where your grandfather's just sitting down for lunch. Your gun's in perfect condition, you're going to be firing it at point blank range, and you've performed extensive DNA testing to prove he is in fact your biological grandfather, we have all our bases covered. You walk in, pull the trigger, and before you know it there are granddad brains dripping off the walls.
 |
| "And that's what happens when you only put a five pounds in my birthday card, bitch." |
At this point, the time line splits in two. There is the first time line, where your granddad finishes his lunch in peace and goes on to have grandchildren who harbour some sort of unspecified resentment towards him, and then there's the new time line, where he doesn't. You're not about to disappear, you're fine, because you're from time line number one, but in time line number two, you will never be born. When you return to the future, it won't be a future you recognise, and nobody's going to recognise you.
 |
| For an insanely complicated version of this, see the movie Primer |
This version of time travel helps us resolve a whole lot of other paradoxes. Remember the mystery of who wrote my paper? Well now we can solve that one. At some point, there was a time line where Chris wasn't conveniently saved by a postal delivery from the future, and went on to look really quite silly. Unable to live the humiliation down, he decides to actually write the paper, then take his DeLorean and post the paper to his past self. Rather than altering his own past however, that version of Chris ends up creating a new time line, which we've already described. After that, the loop becomes self sustaining, spreading out across various alternate time lines.
 |
| Of course, when I tried to redraft it, things got kinda complicated |
If you put your mind to it, you could probably even create a loop of the kind seen in All You Zombies, although after a few different time lines, that baby would be seriously inbred.
Of course, even this model of cause and effect has some problems. For example, stories that use this model rarely, if ever, explain what happens to the original time line. Does it break down and disappear as soon as our time traveller leaves? Does it keep going on without him? If it keeps going on without him, then just what is the point of Skynet sending the Terminator back to kill John Connor, and why bother sending Kyle Reese back to stop him? In time line one, Skynet's already beaten. If you think about it too long, it also makes you wonder, just who was John Connor's real dad in the original time line?
 |
| He wasn't originally John Connor's father, he was just aiming for the best "Your mum" zinger in history |
Your time traveller will also have to be careful not to do anything that will prevent their past self from going back in time. If their past self doesn't get in the time machine, it won't cause anyone to fade away, but now there are two versions of your time traveller.
If you're telling your story from the perspective of the past that's being travelled to, things can get even more complicated. Kyle Reese says he's from “one possible future”. Implying there is more than one possible future. You could feasibly get time travellers from several possible futures, or even the same time traveller coming from several possible futures. Personally I'm still waiting for Terminator/Planet of the Apes crossover, where the hyper evolved apes duke it out with robots to see who gets to overthrow humanity. Basically I want to make Arnold Swarzenegger fight a gorilla.
 |
| Come on! I know you've still got it! |
We've looked at various different ways of portraying time travel over the course of this paper, but the important thing to remember is that time travel is a story-telling device, it can't make the story on its own. The stories we've looked at have been about a complicated romance, a dweeb trying to get the girl, and killer robots (which can make a story on their own). Time travel allows us to do things with those stories we otherwise wouldn't be able to. We can see relationships you otherwise wouldn't get to portray – how a parent and child might get on when they're the same age, how an ageing conservative might get on with his hippyish, lefty younger self. We can see how characters react to seeing their own future, or how their lives might have turned out differently. But the thing to remember is, if your characters are convincing and compelling enough, your time travel logic can be as sloppy as you like.
