Imagine a bubble. Nothing else, just a bubble in an empty room, floating maybe halfway up. Now, fill that bubble with tiny bubbles. So, you have a bubble full of bubbles floating in empty space. Now, at that level where the bubble is floating, fill it up with a single layer of bubbles, each full of their own smaller bubbles. Above and below this layer of bubbles then appear nearly identical bubbles, stretching in columns from the floor to the ceiling.
Each of these bubbles, however, is not a sphere, it is a hypersphere; the four dimensional shape that is to a sphere what a sphere is to a circle. Just like a sphere would seem infinite to a two dimensional being, a hypersphere appears infinite to a three dimensional consciousness; you can go forever in any direction, however you will circle back around to your origin eventually.
One of those bubbles is our universe, with our laws of physics. From there we added bubbles inside our bubble. These are one of the stranger features of our proposed reality. The universe is full of black holes, rips in the fabric of the universe. Certain mathematical equations exist to describe and explain these holes, and as it turns out the universe itself exactly solves these equations. This leads physicists to believe there might just be universes inside these black holes (Than). Hence the smaller bubbles filling up the larger bubble, which you could think of as pocket universes in our universe.
On our level, there are many many other bubbles alongside ours. These are other universes, though not the classical mirror universe or dark or parallel universe that science fiction loves to explore. These are entirely different realities, with their own distinct laws of physics (Barrau). Some are incredibly similar to ours, others are vastly different. Many would have their own pocket universes, while others very well might be lacking them entirely.
Stacked above and below our bubble, and every other on our level, are nearly identical bubbles. These are the parallel universes. Some events in nature, on a very basic level, could happen in two ways (Tegmark). Let’s not worry about understanding the events themselves, for that is not important. What is important is that they do happen both ways. The universe copies itself, and it happens in one way in one universe, and the other in the other. In each of these universes, we make the decisions we have to, and may very well end up with vastly different worlds within even the most similar of parallel universes. There is the added possibility of our very choices spawning their own universes, but let us ignore that for now as there is yet another level to all of this to deal with. Earlier we stated that the bubble was a four dimensional shape, called a hypersphere.
Scientists now believe there to be eleven dimensions (M-theory). What lies in those extra dimensions we do not know, and cannot even begin to hypothesize with any degree of certainty. There could be life, there could be deities, there could be nothing. We cannot begin to guess, nor directly observe them. After all, how could a two dimensional drawing look up to see the artist?
These eleven dimensions would presumably hold true for all of our parallel universes, but there it ends. The pocket universes and the other separate universes all have their own rules. It would make a certain amount of sense to believe that the pocket universes inside our own would be at least similar to ours, as they were spawned from and are fed by our universe, – and are essentially an extended part of our own – but we cannot be sure of that. As for the other universes, it is entirely possible there are one dimensional universes, and others with a thousand coiled up dimensions. Imagine a universe without any physical dimensions at all? You can’t, it’s too foreign to our reality. Is it possible? Does it exist? We cannot know. For the parallel dimensions we can surmise certain things, but for the other universes we cannot.
There is one last possibility to consider. We know one thing with a fair amount of certainty; our universe is expanding. What we cannot know is what the other universes are doing, those non-parallel to our own. What will happen if our universe expands and makes contact with another universe? Is that even possible, as they do not exist in our own space? We cannot know. What we do know, in our own universe at least, is that nature loves symmetry. Let’s work this up from the smallest levels, using the broadest of strokes.
Atoms are made of clusters of smaller particles. These atoms then group together to form molecules, which come together to form objects. These objects then cluster together to form more complex systems, which form planets and stars, which create solar systems, and from there on to galaxies. Even galaxies cluster together, and these clusters form super-clusters of galaxies. These super-clusters then strand together to stretch across the universe creating a sponge-like texture to the very broad scale universe (TA). We cannot know if that is how any other non-parallel universe is organized, but it seems likely for at least some of them. If this clustering trend continues, as seems likely, the non-parallel universes may well cluster together in some nth dimensional group, implying the possibility of contact, and of further organization on an even grander scale which we cannot even begin to test. One possibility among many is that the universes can and do make contact, with the result being a catastrophic explosion, birthing a brand new universe. Of course, if you really want to throw your mind for a loop, imagine this; if the universes form some larger structure, couldn’t it be another reality itself, with the universe acting like the particles that make up the atoms in our universe? And if they do, what does that mean for our atoms?
Barrau, Aurélien. “Physics in the Multiverse.” CERN Courier. December 2007.
“M-theory, the theory formerly Known as Strings.” Cambridge Relativity: Quantum Gravity. http://www.damtp.cam.ac.uk/research/gr/public/qg_ss.html
“TA: Large-Scale Structure Formation.” Harvard-Smithsonian Center for Astrophysics. http://www.cfa.harvard.edu/ta/lssf.html
Tegmark, Max. “Parallel Universes.” Scientific American. May 2003. http://space.mit.edu/home/tegmark/PDF/multiverse_sciam.pdf
Than, Ker. “Every Black Hole Contains Another Universe?” National Geographic Daily News. April 9, 2010. http://news.nationalgeographic.com/news/2010/04/100409-black-holes-alternate-universe-multiverse-einstein-wormholes/