Very well; I ask you to exhibit one, just one, example of a wavefunction in which you can (1) specify which parts are the "worlds" / "branches" / whatever-you-call-them (2) explain how it is that those parts are relativistically covariant (3) explain why it is that one branch can have an unequal probability compared to another branch, when they are both equally real.
Let's call |1> and |0> the two energy states of a two-state system. We can then imagine the system being in the state (3/5) |1> + (4/5) |0>. If the state of the universe except for this system is called |U>, the two "worlds" (or as I like to call them, "dimensions in Hilbert space") are then |U> x |1> = |U1> and |U> x |0> = |U0>.
Using this example, could you more specifically state your problems?
These are extracts from some Facebook comments I made recently. I don't think they're actually understandable as is—they're definitely not formal and there isn't an actual underlying formalism I'm referring to, just commonly held intuitions. Or at least intuitions commonly held by me. Ahem. But anyway I figure it's worth a shot.
A proposal to
rationalizederive magick and miracles from updateless-like decision theoretic assumptions:(On Google+ I list my occupation as "Theoretical Thaumaturgist". ;P )