Saturday, February 08, 2014

determinism and many worlds

There is a school of thought—how legitimately scientific this school is, I don't know—that contends that, at every moment at which I have a choice, this universe splits into many universes, each incarnating one of the possible choices. In the kitchen, I pick up a knife. Now what do I do with it? The cosmos splits, and I do everything it's possible to do: in one universe, I cut up a potato. In another, I stare blankly at the knife for a while. In a third, I direct the knife's point at my face and carve out an eyeball. So to answer the question, "What did Kevin do at that moment—A, B, or C?", I would have to reply, "Yes": all the possibilities are instantiated. To be honest, this way of thinking confuses me because it seems the total raw number of universes created depends on human freedom.*

So it's time for a thought experiment: what if we aren't free? What if Sam Harris is right and we exist in a hard-deterministic universe in which only one state of affairs is possible from moment to moment? That would seem to imply that, no matter how much the cosmos might want to shatter into different world-lines, it can't: only one world-line can ever be actualized. The narrative of the entire universe could be rendered as frames in a linear film. It seems, then, at first blush, that the many-worlds hypothesis and hard determinism are incompatible.

I've written about the many-worlds problem before. In fact, I also feel that human freedom is impossible in a many-worlds scenario. See here.

*Random quantum fluctuations might also cause universe-splitting: in Universe A, a particle zigs; in Universe B, the same particle zags; in Universe C, the same particle zogs; in Universe D, the particle zegs, and so on ad infinitum.


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