In his 1985 paper, “Quantum theory as a universal physical theory”, Deutsch writes:
> I have pointed out several times in the preceding sections that the C.I. and the Everett “interpretations” are really different formalisms for quantum theory—in effect, different physical theories. It is usually claimed that although their assertions as to the nature of objective facts are radically different, the two “interpretations” agree about all subjective experiences of observers, and cannot therefore be distinguished experimentally. That this claim is false is shown by equations (40) and (42) which summarize the different predictions of the two “interpretations” concerning further measurements on subsystems one of which has completed a measurement on the other.
I judge by the fact that there aren't very many people doing experiments meant to distinguish the various proposals that physicists continue to generally believe there isn't much that can be done to distinguish the various interpretations from each other. Given the incentives to complete such an experiment and even just eliminating one possibility (even if one couldn't nail down which is true), and the fact that it seems to me many of the possible experiments that could do this are more lab-bench style experiments with a laser and a handful of mirrors and electronics rather than Large Hadron Collider-class experiments, I'm guessing the idea that the theories are distinguishable is a minority view, and one that the minority has not yet managed to do something so compelling with that the majority has no choice but to take note.
> I have pointed out several times in the preceding sections that the C.I. and the Everett “interpretations” are really different formalisms for quantum theory—in effect, different physical theories. It is usually claimed that although their assertions as to the nature of objective facts are radically different, the two “interpretations” agree about all subjective experiences of observers, and cannot therefore be distinguished experimentally. That this claim is false is shown by equations (40) and (42) which summarize the different predictions of the two “interpretations” concerning further measurements on subsystems one of which has completed a measurement on the other.
https://pdfs.semanticscholar.org/c948/44bc9128e77077abdf36a6...