I suppose the basic intuition here is, “Superposition is real for small things, we have no evidence that it breaks down for large things, and superposition means multiple instances of the thing superposed; therefore, many worlds, not just many electrons.”
But is it clear that superposition means multiple instances of the thing superposed? Consider the temporal zigzag interpretations. There it is supposed that there is only one history between first and final observed event, and that the amplitudes are just the appropriate form of probabilities, not signs of multiple coexisting actualities. The temporal zigzag theorists cannot yet rigorously show that this is so; but the many worlds people cannot show that they get the right probabilities either. Therefore, even at the level of the individual quantum process, there is no evidence to favor the interpretation of superposition as denoting multiple actuality rather than multiple possibility.
I suppose the basic intuition here is, “Superposition is real for small things, we have no evidence that it breaks down for large things, and superposition means multiple instances of the thing superposed; therefore, many worlds, not just many electrons.”
But is it clear that superposition means multiple instances of the thing superposed? Consider the temporal zigzag interpretations. There it is supposed that there is only one history between first and final observed event, and that the amplitudes are just the appropriate form of probabilities, not signs of multiple coexisting actualities. The temporal zigzag theorists cannot yet rigorously show that this is so; but the many worlds people cannot show that they get the right probabilities either. Therefore, even at the level of the individual quantum process, there is no evidence to favor the interpretation of superposition as denoting multiple actuality rather than multiple possibility.
.> But is it clear that superposition means multiple instances of the thing superposed? Consider the temporal zigzag interpretations.
Consider also that supersposition is observer-relative.