The parallel universe theory is roughly explained like this: There is another earth out there with another copy of you in it, who has done all of the exact things you have done up until this point in time. This theory sounds far-fetched without any background, so let me give a little explanation of the concepts that this theory is built upon.
There are quite a few variations of the parallel universe theory. Max Tegmark wrote a book called Our Mathematical Universe, which I believe explains them the most elegantly. It’s a wonderful book and I highly recommend it if you have any interested in Astronomy or Physics. Tegmark explains four separate parallel universe theories which he organizes into four levels. For the sake of this article I am going to stick with the easiest level to understand, the Level 1 Multiverse.
Before I explain the theory, I want to clarify one thing. When I use the term "universe", I am describing everything that we believe physically exists. So if you were to fly a rocket ship in any direction for any duration of time you would remain within, what I am describing as, the universe. I am about to describe the Level 1 Multiverse theory, which is a confusing name. In this theory, there is still only 1 universe. The duplicate earth and duplicate version of you exist within the same universe, as previously described, so you could find him/her if you flew your rocket ship far enough. Don’t let the term "parallel universe" and "multiverse" confuse you because I am still only talking about a single physical space.
If you believe that the universe is infinite in size, then you are committing to beliefs in mathematical laws that must also be true. Here are the assumptions that build the foundation for the Level 1 Multiverse theory.
- Plants, animals, people, stars, and everything else in our physical universe are simply combinations of atoms at the lowest level. If you were given a box full of the right atoms, you could piece them together to make an exact physical copy of yourself.
- If you had a box full of the right atoms and shook them up once, it is very unlikely that they would come together to create a duplicate version of you, but there is a chance that this could happen. (Shaking the box of atoms is just an anlogy for arranging them randomly in 3 dimensional space)
- If you shook the box a thousand times, the likelihood that one of the shakes would result in a copy of you is still very slim, but higher than if you only shook it once. But, if you shook it an infinite amount of times, every single combination of atoms in that physical space would occur. And it is guaranteed that you would shake up a version of yourself, not only once but, an infinite amount of times.
- If you shook two boxes at the same time an infinite amount of times, it is guaranteed that you would shake up a version of yourself and a version of me an infinite amount of times.
The theory that our universe is infinite in size, means that every combination of atoms will occur an infinite amount of times. So, as you fly your rocket ship you should expect to eventually pass a combination of atoms that is the same as earth. And then another one and another one, as you keep flying further. On the first earth that you pass, there might not be any combination of atoms that are an exact copy of you. But eventually you will pass an earth that has a copy of you on it. And as you keep flying further you will pass another earth that has a copy of you on it.
Since the universe is infinite, there are infinite copies of earth in the exact physical state that our Earth is in right now including the organisms that live on it (you and me). There are also an infinite subsets of these copies, whose state 1 year ago, is the same as our Earth’s was 1 year ago. In fact, there are an infinite subset of these copies that have had the exact same history that our Earth has.
All of this leads us to the following deduction. Since the universe is endless, there are infinite combinations of atoms. This means that there are infinite copies of the Earth with the same exact physical past. There isn’t just one copy of you out there, there are infinite. One of them will become a millionaire tomorrow, one of them will get hit by a train tomorrow. Every single thing that could happen to you, has happened to a copy of you. And every single thing that can happen to you, will happen to a copy of you.
So do you believe that there is a parallel universe out there with a copy of you in it? There are a large number of smart people who do. But, I don’t blame you if you don’t. The truth is that I don’t believe it. I believe the description of what would happen with atoms in an infinite physical space. In an infinite physical space, the Level 1 Multiverse would exist because every combination of atoms would occur an infinite number of times. So how can I believe this, but not believe in the Level 1 parallel universe?
I guess I don’t believe that we live in an infinite space. This could be a whole new article, so I’m not going to get into it too deeply. Basically, I believe that space is a loop in a higher dimension. I believe that if you fly in your rocket ship in one direction for long enough, you’ll arrive back at Earth. An ant has no idea that the surface of the earth is curved. Yet if he walks in the same direction for long enough he will arrive back at where he started. I believe that would happen to us as well.