When you think of a good idea for a science fiction story, time travel quickly comes to mind. Paradoxically, time travel stories are both incredibly hard to write and have been done to death. And then some.
Why do writers like them so much? What are some of the ideas and common pitfalls? I’ll talk about the first this week, and cover pitfalls in a second post.
Time travel is a deceptively simple term for a complex set of phenomena. We all travel through time, of course, forward, at a speed of 1-second-per-second. Actually, that is not quite true, but more about that later. Time travel is usually seen as the travelling at a non-regular speed from one point in time to another, often instantaneously, and placed in the realm of science fiction. That leaves a lot of leeway. A time traveller could travel to the future, or could travel to the past. They often stay in the same place, although that is strange because the Earth itself moves around the sun, which orbits the centre of the milky way, which moves with the expansion of the universe.
Let’s start simple. Travelling to the future has been proven to be possible by physics, and has actually been tested experimentally. One of the consequences of Einstein’s theories of relativity is that time passes differently for particles (people) at different speeds and under different gravity. Explaining the physics concerned is a bit beyond this post, but suffice it to say that if you were to travel away from the earth at nearly the speed of light, then travel back at the same speed, time would pass much faster on Earth than for you. You’d effectively travel to the future. This is why I say that not everybody travels at the same speed of 1 second-per-second. If you are in a moving car, you actually move at a slower pace, if only a very very small fraction slower than 1 second-per-second. Relative to the rest of us anyway.
Travelling to the past is a more difficult proposition. Physics currently seems to allow it. There are several theoretical ways to do so, using wormholes or fast-than-light travel, but it has not been proven that it can actually be done. It could be that we’re still misunderstanding the universe on this front.
In science fiction
A lot of science fiction has been written about both kinds of time travel. In the Forever War by Joe Haldeman the protagonist travels forward in time by the exact effect described above. In the Time Machine by HG Wells the time traveller goes both to the future and back. Back to the Future is about a young man getting stuck in the past. The list goes on. It goes on a long way.
I don’t recall any stories where the travellers also change their relative position, but they’re probably around. Usually they end up at the same spot on Earth, which is a bit strange, given the Earth’s movement through the space.
This does highlight one of the problems of time travel. Travelling through time is a pandora’s box. If you open it, all manner of problems come out. An experienced science fiction reader can quickly spot those problems and it can ruin the experience.
Time travel paradoxes
Let’s talk paradoxes related to time travel. There are two important ones.
One, you travel back in time and shoot your own grandfather. You are never born and can never go back to kill your grandfather. Paradox!
There are two ways out of this. One is the so-called many-worlds interpretation of the universe. In this case, any change a time traveller makes in the past leads to a different timeline that exists in parallel to the original. The original traveller comes from timeline A, kills their grandfather, creating timeline B where they are never born. Problem solved.
Interestingly, in Back to the Future, they seem to use the many-worlds interpretation of time travel, as evidenced by the second movie, but when the protagonist prevents his mother and father from meeting each other, he is still being wiped from existence – if slowly. In other words, the writers were halfway to sorting the paradox, then re-introduced it – doh.
The other way to get out of the paradox is by viewing the universe as governed by the consistency principle. The one and only timeline is consistent by nature. The time traveller cannot shoot their grandfather, because if they did, they would not have been born and could not have travelled back. Whatever happens to a traveller in the past has always been part of the timeline. A famous example is the movie Twelve Monkeys. Bill and Ted’s Excellent adventure uses the same interpretation, if less articulated. The television show Continuum plays with this idea, and because the main character is stuck in the past, she can not tell if her actions in the past actually change the future, or were always part of the future she comes from.
One interesting take on the consistency principle and many-worlds interpertation is the movie Source Code, I can really recommend it.
The second famous paradox is the causality loop. A prime example of this one, I think, is John Connor in the Terminator, who is the son of somebody who he himself sent to the past. A causality loop is where a certain event (John Connor being born) is caused by a result of that same event (John Connor is born -> John Connor sends a man to the past -> the man sent to the past sires John). The consistency principle would seem a fit for this one, but the Terminator II actually goes for a many-world interpretation where the timeline can be changed. Maybe not look too closely at that one.
Why writers love it
Time travel is awesome! There are a multitude of really cool things that can happen that spice up a story. To science fiction writers, time travel is like a toy that we really want to play with.
One big advantage of time travel is that – as of yet – science is not sure how it can and cannot work. That gives the writer freedom to do as they please. Freedom, yeah!
Because of this flexibility, time travel can be used to do exciting things with the entire MICE quotient: Milieu (setting), Idea (theme), Characters, and Events (plot).
In the Outlander series by Diana Gabaldon, the time travelling is only used – among other things – as a setting. The use of time travel allowed Gabaldon to put a more modern character (relatively anyway) into a historical setting. This allows the historical setting to be filtered through a modern viewpoint, which makes it much easier to highlight things that we would notice, even the historical characters would not.
In the Time Machine, the time traveller goes to a far future, where humanity has regressed to childlike creatures called Eloi, and the ape-like Morlocks. The time travelling is used to push some of ideas Wells had about humanity and its future.
Throwing together characters from different time periods can highlight their differences and commonalities. This makes it easier to create foil characters. As a kid I enjoyed the television show Catweazle, where the titular character was a wizard from the 11th century transported by magic to 1969. If you look at Bill and Ted’s Excellent Adventure, one of the key things that makes the main characters interesting, is the fact that their empty-headedness is contrasted with the knowledge that they are worshiped as near gods in the future.
Time travel also allows all manner of interesting plots. In back to the future, the protagonist accidentally prevents his own birth. The time travelling provides a conflict for him to solve; a ticking clock that ends with his own death. Twelve Monkeys and Source Code do something similar, by putting the protagonist in the position where they travel to the past and might be in a position to prevent a great catastrophe. The question is, can they?
Another possibility is to create plot twists. I’ve already named some movies that have pretty big ones, caused directly by the time travelling. One I already spoiled is in Terminator, where John Connor turns out to have sent his own father to the past. I’ll not spoil the others.
One notable example I want to name is in the television series Red Dwarf. This is a comedy show where in the episode Tikka to Ride, the main characters end up accidentally preventing the Kennedy assassination and try to fix this. Eventually they get everything so tangled up that….well, you should really watch it.
The possibilities with time travel are endless. I’ve named some examples, but there are many more. Writers love time travel because there are limitless possibilities for doing interesting things with it.
Unfortunately, a lot of things have been done, and done often, leading to them being done too much. Worse than this are the stories that just get it wrong. I’ll talk about that in a second post.