Alternate universes or alternate realities are often used in time travel stories. I have usually seen it done in two different ways. One is that a change in the timeline creates an alternate reality that has off-shot from the actual timeline. The other is that all possibilities exist simultaneously in an infinite number of alternate realities and universes. The first option is usually used as an explanation for the complication of time travel, although sometimes not explained in a satisfactory matter because the very act of traveling back in time should technically change the timeline. Unless it already happened that way to make the world what it is – you trying to change time is actually what causes the timeline – but that is an entirely separate discussion.
The other option just opens up so many possibilities of how things can be done, especially if you allow the characters the ability to jump between the various realities. This leads to interesting questions of how many realities the characters themselves actually exist in. Then would you traveling to a different time give you the memories of the alternate reality or would the time traveller / reality jumper exist outside of that reality? So many directions you could take this sort of story and so many ways for alternate realities to just break your brain! Continue reading