Worlds of possibility

I just finished reading Brian Greene's book, Hidden Reality. In it, he discusses nine current theories regarding multiple universes. Greene is a physicist who writes for a nonphysicist audience, making some pretty complex topics more comprehensible to the untrained reader. However, I'm only beginning to become familiar with some of the concepts through the reading I've done, and there's still some math that goes over my head (or at least, doesn't go into it; my eyes skim the words without taking them in), so I'd be lying if I claimed to actually understand the theories. But I grasp the ideas enough to get excited about them and to start playing around with them.

These theories are borne out of the math done in various areas of physics research: string theory, quantum mechanics, etc. It's not like they went out looking to see if multiple universes existed; this is where the math led. I started reading about multiverses to try to understand more about Sandy's current experience and to imagine a way to her. The multiverse theories I find most compelling for my purposes are the Brane Multiverse and the Quantum Multiverse.

Here are Greene's quick summaries of each:

Brane Multiverse: In string/M-theory’s braneworld scenario, our universe exists on one three-dimensional brane, which floats in a higher-dimensional expanse potentially populated by other branes – other parallel universes.

Quantum Multiverse: Quantum mechanics suggests that every possibility embodied in its probability waves is realized in one of a vast ensemble of parallel universes. (He also refers to this as the Many Worlds Multiverse)

After reading other books about string theory and the work being done with the Large Hadron Collider, I was fascinated by the idea of branes, universes in other dimensions that could be just millimeters away from us. I still am. With my unsophisticated knowledge of how all this works, I can't help wondering if Sandy's just on another brane, given her simultaneous proximity and distance. When people talk about "crossing over," could it literally be that we cross over to a nearby universe on a different dimension? Greene's discussion of the Brane Multiverse did nothing to dissuade me of the possibility.

But what delights me is the Quantum Multiverse theory. It comes from quantum mechanics and the existence of probability waves. I won't take you down the long road Greene followed in explaining just how probability waves lead to multiple universes, but it is persuasive. Instead, I'll jump right to the part that is most compelling to me (and to plenty of science fiction writers in print and on TV and in movies). When people talk about parallel universes or alternate universes, this is the theory they're relying on. In short, the theory says that there are universes out there that encompass every possibility.

Say, for example, two people meet, fall in love, have children. The theory posits that there are universes where they never met, or where they met but didn't get together, or where they got together but didn't have children, or where they had more children or fewer children. Essentially, at every decision point, there is a universe for each possible outcome. "Decision point" is my phrase; Greene didn't say that, and I don't think there would have to be a conscious decision - just something that did or did not happen, that might have been different.

Say, for example, a person develops cancer. Well, it could be that there are universes where those cells never mutated, or where the body repaired the mutation.

In some universes, I bet she sings professionally. Hard to
imagine that there'd be any universe where she didn't have
an amazing voice, and to love sharing it.

I've been playing with this for the past couple of days. It pleases me immensely to think that there are universes out there where Sandy is not only alive but healthy, happy, fully herself, never even having suffered from depression, let alone cancer. There would be universes where we're both dead, where we never met, where one or both of us were never born. There are almost certainly universes where we broke up in 1996, after a horrible fight during our return from Glacier National Park. In some of those universes, we got back together, and in some we didn't.

The word never is a heavy, malevolent burden that I've been carrying around. But with the Quantum Multiverse, never loses some of its power, because the theory is all about what is possible.

As I was walking to the library today, it occurred to me that there may well be a universe where I died and Sandy lived and she's walking to the library thinking about me living in an alternate universe. And then I thought about all the shows where a rift opens between universes and sometimes people or other beings slip through. I imagined glimpsing her through such a rift, and then having to convince her that she should come to my world while she was telling me to join her in hers. If I went to her, people in this world would still be in pain, so it'd be much better for her to join us. But if she left her world to come here, people in that world would experience pain. So maybe we need to find a rift between our world and a universe where Sandy is exactly herself, but missing me, and surrounded by mean, horrible people who wouldn't know to feel pain at her absence, so she could come here without guilt.

I think it's a good thing the library is a mile away; I'm able to work out a lot of complex issues as I walk!