In so far as I understand what the “preferred basis problem” is actually supposed to be, the existence of a preferred basis seems to me to be not an assumption necessary for Everettian QM to work but an empirical fact about the world; if it were false then the world would not, as it does, appear broadly classical when one doesn’t look too closely. Without a preferred basis, you could still say “the wavefunction just evolves smoothly and there is no collapse”; it would no longer be a useful approximation to describe what happens in terms of “worlds”, but for the same reason you could not e.g. adopt a “collapse” interpretation in which everything looks kinda-classical on a human scale apart from random jumps when “observations” or “measurements” happen. The world would look different in the absence of a preferred basis.
But I am not very expert on this stuff. Do you think the above is wrong, and if so how?
In so far as I understand what the “preferred basis problem” is actually supposed to be, the existence of a preferred basis seems to me to be not an assumption necessary for Everettian QM to work but an empirical fact about the world; if it were false then the world would not, as it does, appear broadly classical when one doesn’t look too closely. Without a preferred basis, you could still say “the wavefunction just evolves smoothly and there is no collapse”; it would no longer be a useful approximation to describe what happens in terms of “worlds”, but for the same reason you could not e.g. adopt a “collapse” interpretation in which everything looks kinda-classical on a human scale apart from random jumps when “observations” or “measurements” happen. The world would look different in the absence of a preferred basis.
But I am not very expert on this stuff. Do you think the above is wrong, and if so how?