Down the Loopers Loop, Part One
October 3, 2012 § Leave a comment
Having recently seen Looper(A good movie, in my humble opinion), I thought now was as good a time as any to look at the common forms of theorised time travel, while I attempt to get my head around exactly what kind of internal consistency it used(Some of what is posted here may constitute spoilers, though none of them at this time are for Looper).
“There are fixed points in time.”
So, let’s start with the very simplest concept of time travel, that is to say that time is fixed. This theory, while long-standing in fiction, is simple enough to understand through what is known as the “Novikov self-consistency principle.” This follows the very simple idea that any event that has the option of changing the timeline has a null chance of happening, so a time paradox simply cannot exist. A well known example would be that of the time turners from Harry Potter, they go back in time, constantly worrying about causing some sort of paradox, but all their events have already happened in the past. Harry is saved by himself, and that’s always the case. This theory typically leads to questions about free will, as if the timeline is set, then nothing you do can change that. This itself comes in two main forms, either the idea that everything that could ever occur in time is already pre-set, or simply that everything “behind” some notion of the “present” is pre-set, with free will allowed only to those who do not travel backwards. Travelling forward in time via this second theory becomes rather complex though, as you move to a point where your present is the past, thus forcing a “fixed” future, and so removing any attempts at free will.
“Time can be rewritten.”
Moving on to the second main concept of time travel, we get the idea that there are no set points, and that anything in time can be changed. The important part of this theory is that everything exists in one timeline. Though, it would be more apt to call this a grouping of theories, as there are many different ideas within it. In something like Back to the Future, almost everything Marty does affects the future in some way, with the changes affecting the future in approximate relation to the size of the change. By knocking down a tree, he changed the name of a park, but by teaching his father to be brave, he causes big changes to his family in his present. He as a character is also set throughout this(excluding the paradox which almost causes him not to exist), with a vision of him in the future allowing him to change his actions in his own near future, thus preventing that future from happening. In this case, it’s avoiding a grandfather paradox in his own future, while also accepting that it could happen within his own past. Another theory here is that time is resistant to change, so while you could go back to try and stop Lincoln from being assassinated, you would ultimately fail, but what you’ve done within that time, your appearance there, and so forth, could have subtle implications on the present, like a different pain colour on someone’s shed, or change to someone’s socio-economic status. This also wouldn’t be a decent time travel piece if I didn’t mention “The Butterfly Effect(the film)” which runs off the idea that any minute change will have sweeping differences over time, also see the “Time and Punishment” section in the Simpsons.
“I can’t think of an appropriate approximate Doctor Who quote to go here.”
The third (and final) main theory of time travel that exists is the multiple universe theorem(or what is sometimes referred to as the Trousers of Time). Typically, this runs off the idea that any time a change occurs, this causes a new universe to be created from that point forward, and any new changed from there onwards cause another split. This theory is typically more internally consistent than the others, as it makes for a set “character” who travelled back in time, and cannot alter their own past, but they are able to alter a different them’s past. A good example would be Dragon Ball Z, where characters travel back in time to warn other characters of future events. Trunks travels back in time to warn other people of their deaths, and in doing so, prevents them from dying, but only in the timeline he travelled to. In his personal past, they are all still dead. This theory also deals the most easily with the Grandfather Paradox, as you’re not killing your own Grandfather, but killing that of a different you, preventing that universe’s you from existing.
There are also a whole lot of other ideas that don’t quite fit into a neat category. One of my favourites is the idea of “beads of time.” This theory, while completely impractical from a writing point of view, is a lot of fun. If you were to imagine that time is like a beaded necklace, with every point in time being a bead, the theory states that by travelling back in time(let’s say to a field), all you’re doing is removing the existing beads until you reach the point you choose, where the beads start going on again. Typically, this would fall under the second theory. Unfortunately, of course, if you imagine that the beads go back up to what had once been your present, the you of there is still there, and would still decide to time travel back to that field, at that time, and all of a sudden there’s an infinite number of you attempting to fill a finite amount of space, and there’s a whole lot of problems. This theory does allow for travel forward though, as you’re simply adding more beads. The point of this is to help reinforce a very simple idea. That is to say that going backwards in time is impossible, but that maybe, just maybe, forwards could be done. Though there’s always the donut idea of time, as presented in Futurama, where they travel forwards through time until the universe repeats, and they’ve essentially travelled backwards.
Obviously, I don’t have a degree in physics, I can’t talk about how probable any of these ideas are, but hopefully this gives you a decent idea of some very, very basic ideas of time travel. Now get yourself ready for part two, where I actually discuss Looper.