I don’t know why, but I enjoy time travel stories. I’m not the only one.
There’ll be references (and spoilers) about the following in this post: Back to the Future, Avengers: Endgame, Kate & Leopold, Harry Potter and the Prisoner of Azkaban, The Umbrella Academy (Netflix show), and Dark.
For the first major category, I’ll refer to “one timeline” types of time travel. (I’m sure that there are technical names for a bunch of these, but I’ll just keep them straightforward and simple.) With this type, I’m referring to characters who travel to the past and change their present (see: Back to the Future, The Umbrella Academy). For example, Marty travels to the past and, by changing some things, affects his family’s life when he returns to the present.
And there are also smaller changes that can change the future big time, in what’s known as the “butterfly effect”. For an example, check out the aptly-title movie The Butterfly Effect.
In The Umbrella Academy, Five travels back from the future to prevent the end of the world (twice), and in the second season, viewers can see how the siblings’ traveling to the past led to a nuclear doomsday, as well as the fact that they changed the future even after they prevented it (by having Reginald adopt other kids instead of them).
Then there are time travel stories where going to the past and trying to change things won’t really make a difference because it’s predestined to happen. An example involves kidnapping a baby who’s known to become a killer but the mother or babysitter replaces the missing child with another baby who grows up to become that person anyway (yes, charming example and there are a few versions out there).
There’s also the idea that traveling to the past was always meant to happen. Harry saves himself (and Hermione) in The Prisoner of Azkaban. In Kate & Leopold, Kate was always meant to be in the past, as seen in the photo that Stuart took of her there (or then?).
Moving away from only one timeline, there’s the idea of going back to the past, changing something, and creating an alternative timeline. The Ancient One explains this in Avengers: Endgame with some nice visual references, and it’s why it’s so important for Captain America to return the Infinity Stones (and Mjolnir) right at the same time that they were “borrowed”.
Then there are the time travel paradoxes (a self-contradictory statement).
The bootstrap paradox refers to the lack of an answer to the question, “What came first, the chicken or the egg?” There are a few examples in Dark, but maybe the easiest to name without getting into complex family dynamics is that a characters travels to the past and gives someone a book. This book is then copied and published for the first time in the past, and it is read in the future, then taken to the past. Who actually wrote it? When did it start to exist in its first version? Well, there is no “first version”—there couldn’t be.
The Grandfather paradox is shown in The Umbrella Academy: Someone travels to the past and kills their grandfather before they helped conceive that someone’s parent, so the someone could never have been conceived to travel back in time.
There are also time loops, although these aren’t about time travel but rather about reliving the same day, over and over again (Groundhog Day, Palm Springs). Once the characters figure out they’re in a loop, they know how the day will play out, with the loop being broken after a particular discovery or significant character growth takes place.
Yes, I know that I left out a lot of other references, but these were the ones that popped into my mind. I can’t go back and change them.
