#41: Parallel vs Alternate Universes

Our 41st prompt comes from Kaggzie. She asks:

Do you think there’s a difference between parallel universes and alternate universes? I’m yet to get a conclusive answer to this 🙂



Fantastic question! For those who are new to the concept of space-time, here’s a primer: #7: Are there other dimensions out there?

To begin with, I think we have to define the Many Worlds interpretation of quantum mechanics by Hugh Everett III. It holds that there are many worlds that exist in parallel to ours – within the same space and time. This interpretation takes the randomness out of quantum physics, because according to it, every time a “random” event occurs, all possible outcomes actually manifest, and the universe splits to accommodate each of them. What this creates is a perpetually branching timeline of events (and worlds) accounting for every possibility.

For example, if you’re running to the train station because you’re late, there are two possible outcomes – you miss your train, or you catch it. In the Many Worlds interpretation, both events actually occur. If in this world you missed the train, there’s actually another world in which you caught it. Another example: perhaps in this world you win one in ten SportPesa bets that you make. It follows that there is a world where you win no SportPesa bets at all, and another one in which you win all of them.

This has many consequences. First, it is the basis of multiverse theory. We previously thought we live in a universe – that is, all the existing matter and space that we observe. However, with the Many Worlds interpretation, it then becomes likely that we live in a multiverse – that there is way more matter and space out there than what we observe. That there are many universes out there, we just can’t/don’t see them. Which brings us to our question.

A parallel universe is a hypothetical, self-contained, separate reality coexisting with one’s own. It is sometimes referred to as an alternate reality, though this connotation can be confusing because the world alternate implies that it is a variant of our own reality (think of how Hepatitis A, B and C are all variants of Hepatitis). Calling it a parallel universe as opposed to an alternate reality removes this expectation of some kind of relationship between our reality and the one(s) in question, which may or may not be there. We use the word parallel because (if the theory holds true) these worlds/realities exist in the same space/at the same time as our own, or as I like to say – we occupy the same space time.

Now I’ll take off my physics nerd hat and put on my comic book nerd hat. An alternate universe is a storytelling device. It allows us to see what would happen if a character made different choices. For example, what if Kal El decided to be a villain instead of a hero? Alternate universes allow us to play “what if” with characters we love in universes we have formed canon around while leaving them untouched. What if Thor was a woman? Check. We create an alternate universe in which Thor is a woman, while leaving the other universes in which Thor continues to be a man untouched. What if Spiderman joined the Fantastic Four? (This actually exists.) Alternate universes also allow us to have crossovers such as Dr. Who meets Star Trek, for example. They also allow us to see what would happen if the Flintstones and the Jetsons swapped realities (this was fun to watch).

So, the first difference is that one is a theory of quantum mechanics, while the other is a storytelling device. The second and more important difference rests in the use of the word alternate. Alternate universes are variants of the original/referenced universes, with one or more tweaks. Even if Kal El is evil, he is still Kal El. When the Flintstones go to the Jetsons’ reality, it is still the same reality that the Jetsons experience, and vice versa. There is still a relation between the alternate universes. Parallel universes don’t have to have any relation, they just exist in the same space-time continuum. We don’t even have to be aware of them.

If I had to be reductive (thankfully I don’t), I would say that considering the context in which both theories exist, all alternate universes are parallel universes, but not all parallel universes are alternate universes.


This post is part of a daily writing experiment that I’m running for a year. I’d love it if you took part! ?

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