There are several scientific theories now dealing with the concept of multiple universes, or multiverses. These ideas force a rethinking of our place in the context of it all. (I just realized that I don’t know the new scientific term for “it all”.) As if the vast reaches of observable space weren’t hard enough to imagine, we have several new versions of reality to digest.
For example, many scientists now think, based on recent observations, that our universe is infinite, with unlimited space and matter. They say the universe is flat and expanding at an accelerating pace. If this is true, then all possible happenings must have occurred somewhere, and there are infinite copies of each of us, some with big differences, some with small differences. In a flat, ever expanding, infinite universe, all possible arrangements of a given number of subatomic particles must eventually occur. This means that there are “universes” where you don’t exist, where the United States doesn’t exist, and where Earth doesn’t exist. This is just one permutation of the concept of the multiverse – the stuff beyond what we can see with telescopes.
It turns out that all of that infiniteness is just within our own spatial bubble. Another theory suggests that even though our spatial multiverse appears infinite from the inside, it is finite from the outside. And outside the multiverse is something called the Bulk. And the Bulk is like Swiss cheese and each hole contains some other spatial multiverses, about which we can know very little at this point. But we imagine that perhaps the laws of physics are different in other multiverses. Perhaps atoms can’t form in them. Or maybe gravity is so weak there are no planets.
Then there’s also the concept of string theory or membrane theory or M theory. This holds that our universe is spread out along a thin membrane in another dimension. And other universes are very close to ours (I want to say within a millimeter, but I’m not positive) but in this higher dimension that we can’t move in. I haven’t heard how M theory intersects with the concept of the Bulk or the spatial multiverse. Is the Bulk on the membrane? Or is the multiverse on it? Or both? Dunno.
It’s hard to know how to relate to all of this, or what it means. We like to think of ourselves as unique, but that doesn’t seem to be likely in an infinite universe. Some people say that these predictions negate free will. They argue that if all possible versions of myself exist carrying out every single possible action in a given situation, that it doesn’t really matter what I choose to do, since some other version of me will choose the opposite. So in this universe, I’m not an axe murderer. In a different universe, I am. So what’s the difference? What’s stopping me from being an axe murderer in this universe? I think the difference is that I’m subjectively me in this universe – the not-axe-murderer-me-universe. Perhaps that’s circular, but it feels like I have free will, and that’s all I have to go on, even if other versions of me have done everything that’s possible. Those other me’s aren’t “me” – the singular entity located in this place and time.
So now that I feel free will is still in effect (at least as much free will as our society affords), it’s nice to think of all the interesting things that the other Earths are doing out there. Here’s a few examples I’ve come up with: there’s the no-wars Earth, the no-poverty Earth, and the no-global-warming Earth. These are good things to imagine the existence of. But if those scientists are right, then those Earths aren’t just imaginary – they’re real. How could those Earths exist? They seem so improbable from what we know, right? But in an infinite, flat multiverse, they must exist.
If they are right, then there is an Earth just like ours is now, that somehow came through all of this, that stopped fighting over resources and territory, that reversed global warming, that helped everyone have the same opportunities. How can we make our world, in our little corner of everything, be more like those Earths?