As someone said elsewhere, the problem there is philosophical - I like the idea, it makes a lot of intuitive sense, but if I can't visit any of the many worlds then it's not really falsifiable. Also, if there was ever a reason to break out Occam's razor it's this one - conjuring entire new universes into being for every available variation at every step of the Planck time seems awfully hairy. I appreciate that it's axiomatically simpler but this seems like an awful lot of information overhead. It would be nice if there were a clearer description of the multiverse in which the many worlds exist in superposition; I'll try Deutsch's Fabric of Reality book to give it another shot.
Some people call it the many-worlds interpretation. I just call it quantum mechanics. An important part of this view is that the scientist running an experiment is not an external observer but he is subject to the same rules of physics. Just as an electron can be simultaneously in many states, so can the human observer.
The interpretation I subscribe to is that measurement is a situation of entanglement. In the electron slit experiment, when you observe the electron traveling through lets say the right slit, subsequent behavior of the electron and the "memory" in the person will be correlated.
I don't know how memory and the brain really work here. I think that is the real question - the mechanics of the brain and an observation.
Regarding Occam's razor, to me this seems like a much simpler explanation of observation than having the wavefunction of the entire universe collapsing when a random human is in the loop.
