> if you think of something like the two slit experiment whether the worlds where the particle goes through slit one or where it goes through slit two exist or not seems to have experimental results as they produce an interference pattern
Intereference is not due to the interaction between "worlds". You don't have "one world" where the particle goes through one slit and "another world" where it goes through another. (If you think that's the case, how does "our world" where the interefence can be observed fit in that description?)
You can perfectly explain interference with a single world where the particle doesn't go through any particular slit. It doesn't have to, because we're not trying to determine which slit it goes through (and if we do, the interference disappears).
Intereference is not due to the interaction between "worlds". You don't have "one world" where the particle goes through one slit and "another world" where it goes through another. (If you think that's the case, how does "our world" where the interefence can be observed fit in that description?)
You can perfectly explain interference with a single world where the particle doesn't go through any particular slit. It doesn't have to, because we're not trying to determine which slit it goes through (and if we do, the interference disappears).