So, what are parallel universes anyway?
Tackling a prevalent science fiction topic that confuses us all
By Aaron Zhao
Every action you make is one out of an infinite amount of possibilities. For instance, instead of reading this sentence, you could be eating a piece of fruit or exercising in your backyard. You could be consuming a slice of apple or peach, or doing pushups or jumping jacks. Parallel universes, which collectively form a multiverse, takes into account all of these different possibilities and essentially creates different worlds for every single one of these outcomes. Welcome to the fascinating world of parallel universes, the alternate realities.
While parallel universes remain a relatively ambiguous topic, it can be explained through three interrelated theories.
1. There are only so many combinations of particles.
Under the assumption that space is flat, it expands forever in all directions. This allows for the distribution and arrangement of particles in many universes into 10^10^122 possibilities, according to space.com. Thus, theoretically, there is an infinite amount of other universes that are identical to the universe you reside in, except that one single action of the future is different.
Take this example: you have a set of numbers [1,2,3,4]. Mathematically, there are 24 permutations, because 4! equals 24. Essentially, here are 24 different parallel universes. 1234 and 1243 are only different in two numbers, with the first two remaining the same; these two worlds are identical in the first two “events”, but the latter two are reversed, similar to how you could stand up right now and drink a glass of water, or drink a glass of water then stand up. These types of universes are called “daughter universes”.
2. Our universe is a bubble amongst many more bubbles.
Our universe stopped inflating 13.7 billion years ago, but other regions of spacetime have not. The idea of inflationary universes, universes that inflated eternally, is known as the eternal inflation (hence, the name). If our universe is merely one of the bubbles in this bubble multiverse, then perhaps there are universes out there on, inflating on flat spacetime.
Naturally one would ask, what if these bubbles collided? Keep in mind that each bubble is drastically different; it could host an entirely different dimensionality, different particles, constants, or physics. Collisions like these may leave cosmic evidence, proving that a multiverse does exist.
3. Our universe is on a very, very large membrane.
The string theory proposes that the primary constituent of everything are actually strings, not particles. These one-dimensional strings supposedly vibrate in 10-11 dimensions, meaning that we can’t see all of it. Brian Greene, an American string theorist proposes that two-dimensional surfaces or “membranes” are allowed by the string theory, meaning our universe could be one of them.
It’s understandable how parallel universes can be confusing. Well, because they are. To properly understand parallel universes, one would have to look further into quantum mechanics, string theory, theory of general relativity, and even metaphysics. Anyways, science fiction never fails to amaze.