Let's assume local laws of the universe, and the many worlds interpretation. How does the physics know which branch of the multiverse here corresponds to which branch of the multiverse there?
What exactly happens when I go from place A to place B, and then return to the place A? The whole universe is a superposition of many configurations. The place A (roughly speaking) is a superposition of many possible variants of the place A. What helps me to return to (a future of) the same variant of place A as I left? When I was in place B, in a sufficiently small time interval (distance between A and B, divided by c) both places were disconnected. And yet the universe somehow remembers to which branches of the place A do I belong.
Its probably a confused question, so please help me fix my intuition. (To avoid unnecessary branches of discussion, let's suppose that I agree with what is explained in the Sequences, although I probably misunderstood a few things. I just want to avoid unnecessary disclaimers like "assuming the WMI interpretation" in the responses.)
Perhaps the single most important thing to realize when adopting the (non-relativistic) MWI is that physical three-dimensional space is not the fundamental space of the theory. The arena in which the theory takes place is configuration space.
The sort of information you're looking for, about which physical space you return to, is encoded in configuration space and the Schrodinger equation. Even though the two different versions of point A you're talking about inhabit the same location in physical space, they inhabit distinct locations in configuration space...
Today's post, Spooky Action at a Distance: The No-Communication Theorem was originally published on 05 May 2008. A summary (taken from the LW wiki):
Discuss the post here (rather than in the comments to the original post).
This post is part of the Rerunning the Sequences series, where we'll be going through Eliezer Yudkowsky's old posts in order so that people who are interested can (re-)read and discuss them. The previous post was Bell's Theorem: No EPR "Reality", and you can use the sequence_reruns tag or rss feed to follow the rest of the series.
Sequence reruns are a community-driven effort. You can participate by re-reading the sequence post, discussing it here, posting the next day's sequence reruns post, or summarizing forthcoming articles on the wiki. Go here for more details, or to have meta discussions about the Rerunning the Sequences series.