New Survey Article on Many-Worlds

I regularly bash many-worlds theory as unscientific and nonsensical, but it is useful to see how it is defended by its proponents. Here is a new encyclopedia article on the subject.

The Everett or Many Worlds interpretation is claimed to be the only realist interpretation that can recover the empirical success of quantum theory in its relativistic and non-relativistic variants, its advocates suggest that it does so without any additions to the physics.

Yes, it claims that, but it has never recovered any empirical success. None.

Probability within Everettian theories is strongly contested and it’s un- clear whether the many distinct resolutions in the literature are mutually incompatible and thus undermine one another ...

EQM [Everettian Quantum Mechanics, ie many-worlds theory] is taken to face two major problems: the preferred basis problem and the probability problem. The preferred basis problem concerns how the universal wavefunction is decomposed, leading to different classical-like branches. ...

The second major problem is the probability problem, which asks how probability can make sense in a deterministic theory where all possible outcomes occur.

Yes, those are two big problems. They cannot define the branches or the probabilities.

The article also discusses other approaches like Bohmian mechanics, and how they do not work either. The obvious inference is that the textbook Copenhagen interpretation of 1930 works better than any of these more modern ideas.