Thank you for your feedback Mitchell,
I'm afraid you have not understood the paper correctly. First, if a system is in a superposition depends on the basis you use to expand it, it's not a physical property but one of description. The mechanism of branching is actually derived, and it doesn't come from superpositions but from eigenstates of the tensor factor space description that an observer is unable to reconstruct. The branching is also perfectly deterministic. I think your best option to understand how the dominance of one branch and the non-reality of the others emerges from the internal observation of unitary evolution is to work through my blog posts. I try to explain precisely where everything comes from and why it has to follow. The blog is also more comprehensible than the paper, which I will have to revise at some point. So please see if you can more make sense of it from my blog, and let me know if you still understand what I'm trying to say there. Unfortunately the precise argument is too long to present here in all detail.
I think it will be helpful if I briefly describe what my approach to understanding quantum theory is, so that you can put my statements in the correct context. I assume a minimal set of postulates, namely that the universe has a quantum state and that this state evolves unitarity, generated by the strictly local interactions. The usual state space is assumed. Specifically, there is no measurement postulate or any other postulates about probability measures or anything like that. Then I go on to define an observer as a mechanism within the quantum universe...
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