(comment edited):
Consider an experiment performed which illustrates the watchdog effect. A radioactive molecule has a half-life of an hour. The molecule is repeatedly measured every second, with a resulting delay in the decay of the molecule, consistent with the hypothesis that the half-life is reset upon each measurement.
This experiment seems to show that upon measurement, something happens, whether it be called collapse of the wave function or XYZ. And, if there is no measurement, that ‘something’ does not happen.
If you think that all worlds are just as real as our world, then under the MWI interpretation you can say that the multiverse is intact. However, the series of measurements has nudged our world to a part of the multiverse where the molecule decays later than it (probably) would have.
(comment edited): Consider an experiment performed which illustrates the watchdog effect. A radioactive molecule has a half-life of an hour. The molecule is repeatedly measured every second, with a resulting delay in the decay of the molecule, consistent with the hypothesis that the half-life is reset upon each measurement.
This experiment seems to show that upon measurement, something happens, whether it be called collapse of the wave function or XYZ. And, if there is no measurement, that ‘something’ does not happen.
If you think that all worlds are just as real as our world, then under the MWI interpretation you can say that the multiverse is intact. However, the series of measurements has nudged our world to a part of the multiverse where the molecule decays later than it (probably) would have.