Tragedy
There are two kinds of time-travel stories.
There are time-travel stories that explore the many-worlds hypothesis. Going back in time and making a change forks the universe. But the universe is constantly forking anyway. So effectively the time travel is a kind of universe-hopping (there’s a big crossover here with the alternative history subgenre).
The problem with multiverse stories is that there’s always a reset available. No matter how bad things get, there’s a parallel universe where everything is hunky dory.
The other kind of time travel story explores the idea of a block universe. There is one single timeline.
This is what you’ll find in Tenet, for example, or for a beautiful reduced test case, the Ted Chiang short story What’s Expected Of Us. That gets straight to the heart of the biggest implication of a block universe—the lack of free will.
There’s no changing what has happened or what will happen. In fact, the very act of trying to change the past often turns out to be the cause of what you’re trying to prevent in the present (like in Twelve Monkeys).
I’ve often referred to these single-timeline stories as being like Greek tragedies. But only recently—as I’ve been reading quite a bit of Greek mythology—have I realised that the reverse is also true:
Greek tragedies are time-travel stories.
Hear me out…
Time-travel stories aren’t actually about physically travelling in time. That’s just a convenience for the important part—information travelling in time. That’s at the heart of most time-travel stories; informaton from the future travelling back to the past.
William Gibson’s The Peripheral—very much a many-worlds story with its alternate universe “stubs”—takes this to its extreme. Nothing phyiscal ever travels in time. But in an age of telecommuting, nothing has to. Our time travellers are remote workers.
That book also highlights the power dynamics inherent in information wealth. Knowledge of the future gives you an advantage that you can exploit in the past. This is what Mark Twain’s Connecticut yankee does in King Arthur’s court.
This power dynamic is brilliantly inverted in Octavia Butler’s brilliant Kindred. No amount of information can help you if your place in society is determined by the colour of your skin.
Anyway, the point is that information flow is what matters in time-travel stories. Therefore any story where information travels backwards in time is a time-travel story.
That includes any story with a prophecy. A prophecy is information about the future, like:
Oedipus will kill his father and marry his mother.
You can try to change your fate, but you’ll just end up triggering it instead.
Greek tragedies are time-travel stories.