| All depends on the context. Does it make sense to talk about propagating splitting in this context? Surely no - for three reasons: 1. You're describing a time evolution _of the subsystems_, which isn't really a thing in the MWI. A many-worlder would say, instead, that the Universe has split a bunch more in the interim. He would point to the time evolution of the state of the Universe, and perhaps there have a discussion about how the inseparability of particular subsystems has propagated over time. Put differently, the many-worlder might say the correlations of these particular relative states with one another propagated over time. What you've done, Everett would call characterizing branches of the universal state in a space-like locality. 2. Split != superposition. Frequently, splitting in MWI is identified with decoherence, so in that sense there is a self-consistent way to describe local splitting - but then you'd really mean, when you referred to the splitting of "an object" or "a system", that Universal splitting had occurred in such a way as to cause the object to exist in some particular multiple new branches. 3. None of this line of discussion helps the parent gain an understanding of how MWI is importantly different from (and the same as) other interpretations of QM. It's far too shallow to amount to any real expert insight and yet too technical to amount to any real layperson insight. What can a discussion on propagating splitting illuminate here? It seems to me that it is a less than useful idea for the parent and readers like him/her, and many-worlds is more clearly understood without it. |
In my head I'm thinking about the time evolution of the global state, but examining the reduced state over certain subsystems at specific points in time.
> Split != superposition. Frequently, splitting in MWI is identified with decoherence
Decoherence is a superposition effect, is it not? Entanglement with the environment, i.e. a superposition of system-environment states.
> then you'd really mean, when you referred to the splitting of "an object" or "a system", that Universal splitting had occurred in such a way as to cause the object to exist in some particular multiple new branches
Yes, this is what I mean.
> What can a discussion on propagating splitting illuminate here?
Tbh I think it's unlikely that the parent is still following but I'm continuing for the selfish purpose of trying to better understand your point. That said, I believe that considering my toy example of a global quantum state in one dimension would illuminate their question about superpositions propagating from here and alpha centauri and meeting in the middle.