Reality, or perception of such, is now being discovered to be just as vast and insignificant as even the most fearful would assume. Let me clarify. It is vast, as there are a multitude of "realities" and dimensions both present within "our world" and in our external and internal realms. However, our reality is insignificant as it is a microscopic fleck in the multiverse. A common misconception is that our universe has borders. This has been disproven, and is supported by modern science that its bounds are truly endless. How can we know this? What does this mean for us? How does our consciousness play a role in proving this theory?
1. We only witness a small amount of "reality."
Although there is an abundance of life we know operating around us that we may not be necessarily be watching, there are also vast worlds within "our world." It's reasonable to believe not only due to our lack of sight, as we can only see certain ranges of light, that there are other bodies of movement or existence around or near us. Our concept of space has been drastically off until recently, and we even know the exact "measurement" is merely a comforting linguistic form. There are to be many dimensions within our world as a collective whole, and more interestingly, they're affecting various scenarios in our current dimensions, or only the ones we can see.
2. Science (physics) is funding research to prove there are a multitude of dimensions.
The more research that goes into the study of the universe, the more is discovered of its endless-ness. There are no borders, only our own delusion. The more we find that it expands beyond our realm of knowledge, it looks as though we're simply a bubble in a vast universe of many, many bubbles. As the complexity grows, the fundamental research for physics does as well.
Inflation is the notion that the universe expanded rapidly after the Big Bang, in effect inflating like a balloon. Eternal inflation, first proposed by Tufts University cosmologist Alexander Vilenkin, suggests that some pockets of space stop inflating, while other regions continue to inflate, thus giving rise to many isolated "bubble universes."
3. Quantum mechanics suggests infinite possibilities.
Rather than giving a definite amount of universes, research has rather suggested infinite possibilities are among us. They break mathematics and our common knowledge. As Greene stated, "Our universe is one of potentially numerous 'slabs' floating in a higher-dimensional space, much like a slice of bread within a grander cosmic loaf." We would have to be naive to assume our superiority in our limited knowledge and claimed world.
4. What space does your consciousness "take up"?
This question has yet to be answered, but I want to ask it, as it does have weight in the argument towards our multiverse. I believe we can all agree our thoughts and mind, although responsibilities of the brain, have external residence to our physical form. There's little research to show where our thoughts and soul lie on a mapped existence. However, this is due to our lack of knowledge, as human intellect is severely limited.
5. Double-slit theory.
Some physicists offer the multiverse as an alternative to wave function collapse. According to this theory, our observation doesn't retroactively determine the proton's path, which seems counterintuitive, but the particles have branched off into many different possible universes, and our observation of a single path is a function of our existence in a specific universe.
To explain better, imagine two pesky children trying to get to the cookie jar. However, one of the kids is simply a friend and shouldn't be at the home past dinner time. However, little Sally needs assistance in reaching the cookie jar. So the two kids, when alone, run freely through the house and obtain the cookie jar. This is achieved through both of their motions: going through two doorways to reach the kitchen that holds the cookie jar. However, when little Sally's mom watches from the staircase, it only appears as little Sally is entering the first doorway and ends up in the kitchen, again alone, as her friend wasn't seen, because little Sally "knew" they were being watched.