- “Go then, there are other worlds than these.” -Stephen King, The Dark Tower
One of the most exciting and enticing topics to speculate about is the idea that our reality — our Universe the way it is and the way we experience it — might not be the only version of events out there. Perhaps there are other Universes, perhaps even with different versions of ourselves, different histories and alternate outcomes, than our own: a multiverse of sorts. For our Ask Ethan column, people of all levels-of-expertise have sent in their questions and suggestions, but this week’s selection comes from a fellow astrophysics researcher, Amanda Mashburn, who asks the following:
I’m curious for your opinion on Multiverse theory. At AAS there was a plenary talk on parallel worlds, specifically if they’re science or sci-fiction. What are your thoughts on the subject?
So, I learned a lot from this article about the expansion and origin of the universe, but his understanding of many-worlds / multiverse seems a little off. The talk was by Max Tegmark, and Tegmark's multiverse model covers several layers of multiverses, ranging from highly-probable to highly-speculative. The article only talks about the level I multiverse: space outside our observable universe. Level II is a more traditional multiverse, with different universes arising from different big-bang events. The many-worlds interpretation doesn't come in play until Level III, and has nothing to do with the expansion of space. As I understand it, the many-worlds interpretation suggests that any time a quantum event might happen, the universe splits in two. The event occurs in one universe, and doesn't in the other. This is the level where you get crazy terrifying effects like quantum immortality. Level IV is basically platonic realism, where anything that is possible exists. In Tegmark's version, "anything that is possible" is replaced with "anything that can be mathematically modeled". An interesting consequence of this level concerns the morality of simulating a suffering mind. At this level of multiverse, simulating a suffering mind doesn't cause that suffering to occur; It just allows observation of that suffering, which already exists. I've been wanting to create a "quantum life insurance" business. I would buy a quantum hardware RNG, and every day generate a few hundred megabytes of random data. I would then run that data as an executable on my computer, and see if I had discovered strong ai. If I had, I'd ask it to develop the ability to scan and simulate human minds, and I'd upload the minds of my subscribers. It seems like this should actually work if the level III many-worlds interpretation is correct, but would be unnecessary under the level IV model. And if the Universes are all the same as one another as far as physical laws go, and if the number of these Universes is truly infinite, and if the many-world interpretation of quantum mechanics is completely valid, does that mean that there are parallel Universes out there, where everything in it evolved exactly the same as our own Universe did, except one tiny quantum outcome was different?