I usually interpret empirical indistinguishability as “no conceivable distinguishing experiment” rather than “no feasible distinguishing experiment”.
Yes, indeed. And it seems like there is a way to potentially falsify MWI, after all (see below). There is no way of falsifying the orthodox approach (“shut up and calculate, unless you can say something instrumentally useful”) as yet, because it does not treat collapse as “objective”, only as a calculational prescription (this is the part EY completely refuses to acknowledge, and instead goes on constructing and demolishing some objective collapse model). To falsify the orthodox approach one has to show that the Born rule is violated macroscopically, e.g. that you can see something other than a single eigenstate after a measurement, or that the measured probability of it is not the square amplitude.
Now, back to the experimental testing. If I understand it correctly, the quantum cantilever experiment of Bouwmeester, once performed, is likely to show one of two things:
Such a macroscopic object can be put into a superposition of two different spatial states, thus violating the decoherence limit proposed by Penrose. This will falsify his specific model of gravity-induced single world, and would thus be a reason to update toward MWI, though there is still no contradiction with the orthodox (unitary evolution+Born rule) prescription, unless the cantilever remains in the superposition of states after the measurement (not a chance in hell).
The cantilever remains in a single state, despite the predictions of gravity-less QM. This is by far a more interesting outcome, as it would for the first time show the macroscopic limits of the quantum world. This would score a point for gravity-influenced decoherence and single world, and would be a significant blow to MWI.
There is always a chance that the experiment will show something else entirely, which would be even more exciting.
Yes, indeed. And it seems like there is a way to potentially falsify MWI, after all (see below). There is no way of falsifying the orthodox approach (“shut up and calculate, unless you can say something instrumentally useful”) as yet, because it does not treat collapse as “objective”, only as a calculational prescription (this is the part EY completely refuses to acknowledge, and instead goes on constructing and demolishing some objective collapse model). To falsify the orthodox approach one has to show that the Born rule is violated macroscopically, e.g. that you can see something other than a single eigenstate after a measurement, or that the measured probability of it is not the square amplitude.
Now, back to the experimental testing. If I understand it correctly, the quantum cantilever experiment of Bouwmeester, once performed, is likely to show one of two things:
Such a macroscopic object can be put into a superposition of two different spatial states, thus violating the decoherence limit proposed by Penrose. This will falsify his specific model of gravity-induced single world, and would thus be a reason to update toward MWI, though there is still no contradiction with the orthodox (unitary evolution+Born rule) prescription, unless the cantilever remains in the superposition of states after the measurement (not a chance in hell).
The cantilever remains in a single state, despite the predictions of gravity-less QM. This is by far a more interesting outcome, as it would for the first time show the macroscopic limits of the quantum world. This would score a point for gravity-influenced decoherence and single world, and would be a significant blow to MWI.
There is always a chance that the experiment will show something else entirely, which would be even more exciting.