The multiverse also known as meta-universe or parallel universe is the hypothetical set of infinite universes. This states that the universe we live in may in fact not be the only one. There are five possible theories that explain multiverse. These theories are: infinite universes, bubble universes, parallel universes, daughter universes and finally the mathematical universes. Physicist used math to get to these conclusions. 

The infinite universe states that space-time is flat, stretching continuously, provoking the universe to repeat itself at certain points because there are only finite ways particles can be arranged in space. The repeated universes hypothetically has an exact version of yourself but with different life choices.

The bubble universes arise from the inflation that occurred during the Big Bang. When the Big Bang exploded the universe expanded like a balloon, some areas stopped expanding allowing stars and planets to form while other parts continued to inflate creating bubbled shaped universes. The difference between this theory and the first is that each bubble universe may have different laws of physics making each universe differently. 

Parallel universes says that our universe is formed by other dimensions in higher space time other than the three dimensions that we all ready know off. These other dimensions creates infinite universes. This theory adds the possibilities that the universes in each dimension can crash into each other initiating big bangs,  resetting the universe. 

Daughter universes is based on quantum mechanics. The difference between this theory versus the others is that instead of basing on actual outcomes it focuses probabilities. For example in this universe who have the choice to choose a burger or burrito, in that instant two daughter universes arises where you witness each universe by thinking. 

The mathematical universes states that if the universe is based on math then all the mathematical probabilities are true, for example Murphy Law.


Portals to another world are a staple of fantasy world. Chronicles of Narnia; Stargate; Monsters, Inc.; and many others have portals to another world, all presented differently. I’ll go over some different types of portals and ways to deal with them.

Types of Portals

Portal to a parallel universe

Portals to parallel universes, like the quantum mirror in Stargate SG-1, transfer the character(s) from this world to a parallel one, one where there has been some divergence but where it is still fundamentally the same as where they came from.

There are basically two types of portals you can have for this. You can have a physical portal, like with the quantum mirror, or you can have a purely magic portal. I’ve seen one story where the portal is and worn can be activated and transfers the consciousness to the same body in another world when other!them dies (more or less).

There are three main things to think about for this:

Is it two-way? You need to figure out whether or not it’s a one-way trip, and your character doesn’t need to know the answer to this when they go through the first one. If it is a two-way trip, there should probably be some symmetrical means to get back. It always reads weirdly when they come through by one means and come back by another. There has to be a really good reason for the characters to come back a different way than they came; the physical object only existing in one world is one of the only good reasons I can think of. That doesn’t mean that there can’t be a whole adventure to be able to go back home.

Where do they come out? You have a few options for this. They can come out in an arbitrary place, they can come out at some set magic nexus, they can come out wherever the physical object is on the other side, or they can come out in the same place (longitude/latitude). For each of these options, you need to think about why they come out where they do.

Do they replace alternate!them? Because they’re coming out in a world that they would theoretically exist in, think about whether they replace them or exist in addition to them. In Stargate SG-1, for example, there are times when they show up and there’s another of them there and there are times when other!them is dead and they never interact with them. Both of these have their issues—what happens when you meet yourself, how are you different from other!you, how do people keep from conflating you, etc.—and you need to figure out how to incorporate them into your story.

Portal to another planet

What I’m talking about here is where the characters and the reader know that they are on another planet in the same universe (and often the same galaxy) as where they came from. The classic example of this (and yes, I have a theme) is Stargate, where they use portals to travel to other planets. For this, one of the biggest things to think about is making the new planet(s) livable without making it/them Earth. Do the aliens look human? Are they even humanoid? How do they communicate with each other? How do they communicate with the protagonist?

Also, how did the portals get there? In Stargate, they were seeded through the galaxy, as were the humans, which is why there are humans on many of the planets with Stargates. If there are ones to multiple planets, you also need to think about dialing and identification systems, as well as whether or not characters have other means to get to these planets (i.e. space ships).

Portal to a magic/other world

This is the classic idea à la Narnia, where there is some way to get to another totally unrelated world that is neither on another planet not in a parallel universe. The common story with this is a character or characters on Earth being teleported to a world with magic and either being the “chosen one” or otherwise getting embroiled in political unrest or war while having to figure out their way around.

These worlds tend to look Narnia and/or Tolkein-esque, with foresty pseudo-European landscapes and cultures. As with all fantasy stories, that isn’t at all necessary. You can have them show up in desserts or tundras or marshes or floating cities or underground or literally wherever you want. It’s fantasy.

Another common thing is to have the world be magic with pseudo-European-medieval-except-without-the-gross-stuff levels of technology. You don’t need to go in that direction. You can have whatever type of magic you want with whatever level of technology you want, because these worlds don’t need to have the same historic path as the Earth.

Portal hub

Another option is that there is a hub of portals where a character can enter from any and go through to any other—or whatever other level of security or access you want—and it can end up as some sort of trade or culture hub.

Things to Think About

What is the portal? Whether or not the portal is a physical thing, there needs to be some idea of what the portal actually is. Traditionally it’s something that’s walked through, like a literal gate, but it can also be an object or a teleportation spell.

How does the portal work? Is it activated by touch? Is it activated by magic? Is there a ritual? Is there a specific time it needs to be turned on? Is there a specific place it needs to be? Is there a set of criteria to create it or make it work? Is there a specific length of time for which it can be turned on? Is passing through active or passive?

Who has access to it? This is true both in terms of physical access—who can physically get to it, who knows about it—and in terms of who can pass through magic-wise. There could be a class distinction or a location requirement, or maybe only a select number of people know about it (e.g. Narnia, Stargate).

Can inanimate objects be sent through? Can communication (e.g. radio or sound waves) be sent through?

What is the cost? This is tied into how it works, but also think about what physical objects may be needed, what physical toll opening it or passing through may cost, or what magic may be required.

Can it be opened from both sides? Is it possible to pull someone through to your side or even open up a portal and let people come through from another side without them opening it on their side?

Raise me up

(Raise me up inside)

Cant raise up

(Raise me up inside)