One of my favourite sci-fi concepts is time travel. I've been fascinated by the idea since I was a kid watching the 1960 movie The Time Machine, based on the book of the same name, which was book number 4 on My List. In that story, the Time Traveller is able to travel to the past and to the future with the use of his machine.
I'm not 100% sure which theory of time H. G. Wells goes by in the book because he doesn't go that deep into an explanation, but it seems to me that he goes with a singular set timeline. Since the story is told mainly from his point of view, we aren't sure how much he affects the Eloi and Morlocks once he gets that far into the future, and if his travels there cause the timeline to branch or not. But anyways, it's a great book that popularized the concept of time travel.
In this post I want to discuss a few different theories of time and time travel that I find absolutely fascinating.
Singular Set Timeline
The first and easiest theory of time, I think, is the singular set timeline. In this theory there is only one timeline that cannot be changed. Everything is set in stone. So if you were to travel back in time, it's because that's what was supposed to happen anyway. And by doing so, you wouldn't be changing anything or causing the timeline to branch. Everything that happened happened, and everything that is going to happen is going to happen. In this theory, there's no real free will, since both the past and the future are set.
This theory of time is used in Harry Potter and the Prisoner of Azkaban (one of my favourites), where it is illustrated by the use of a time loop. An example of a time loop is when Hermione and Harry are in Hagrid's hut, and a stone comes flying through the window. When they go back in time, they hide outside of Hagrid's hut and see themselves inside the hut, and then Hermione throws the stone. So the first time around, when Hermione was in the hut and saw the stone come through the window, it was already herself throwing the stone, meaning she was in fact in two places at once.
I love it!
Multiple Branching Timelines
The next most obvious theory of time is one of which we do have free will and can change the past. In this one, we are currently in one timeline, but if we were to go back in time, that act itself would have repercussions and anything we did in the past would alter the future. These changes would cause the timeline to branch out, sending us on a new branch from the one we were originally on, which itself was never set.
This is the scarier theory because you could change something that you had no intention of changing, or cause something terrible to happen! Even scarier, you might not know what exactly you did to cause this effect, meaning you wouldn't know how to rectify it. In terms of writing a story like this, this theory offers more freedom than the singular timeline, because you are free to change things around. But still, just thinking about this version of time stresses me out, because I happen to like the way things are right now!
This version of time is seen in the movie Back to the Future.
Multiple Branching Timelines Independent of You
The above two timelines all center on the person doing the time travelling. By this I mean, the past memories of the person travelling through time do not change because they are the focal point. If they go back in time and change something in their past, their memory of that past event doesn't change because them going back in time to change it was in the future for them. (Hope this makes sense.)
Another way to go about the multiple branching timelines is to make it more complex by having alterations to the past actually alter your memory of that event. I believe this is the theory of time used in the movie Looper. (Great movie btw.) So if you were to go back in time to change something in your own past, then your memory of that event would change as well. Now, this is where things become really complicated. Because if all of a sudden your memory of a past event changes, would you even remember why you went back in time in the first place? Would you be standing there in the past looking around wondering what you were doing there?
This has been a short and shallow dive into three possibilities of time and time travel. I'll go even deeper in another post, but I just wanted to get these thoughts out there in some kind of orderly fashion for us. Time travel is so fascinating and as I said, it's got to be one of my favourite, if not my absolute favourite, sci-fi concepts. It's such a rich framework for a story, offering built-in problems and drama.
Next time, we'll go 10 feet deeper.
Ciao for now!