Physicist Sean M. Carroll has a new video explaining entanglement.
Towards the end, he tells us that he likes the many-worlds interpretation (MWI), but admits that it has two major problems. It doesn't explain anything about the macroscopic world, and it doesn't predict anything.
He does give a tortured argument for assigning probabilities that is supposed to match the Born rule, but he rejected any frequentist interpretation that allows checking the probabilities against experiment.
The MWI is just nuts. Just listen to the advocates try to make sense of it. They are completely unable to make any scientific sense.
I am actually more disturbed by his explanation of entanglement. That is textbook stuff, and he gets it wrong. He says that he is writing an undergraduate quantum mechanics textbook under a contract with a publisher.
So far the quantum mechanics textbooks have been relatively free of the nonsense that Carroll peddles. I hate to think how many people are getting confused by him. I will post more on what he gets wrong about entanglement.
Update: I just listened to another Carroll Q&A. Most of his answers are correct and well-explained, but he sure has some peculiar views. Someone asked if some experiment could distinguish the Copenhagen and Many-Worlds interpretations.
He said no, because the Copenhagen interpretation is not well-defined! He said that no one knows what a measurement is, or any of the other things to make sense out of it.
This is completely crazy. Every QM textbook uses Copenhagen. So do nearly all the research papers. We have trillions of dollars of industry based on QM, from semiconductors to lasers to video screens, and it all uses Copenhagen. None of it uses MWI.
MWI is not well-defined. No one can say what a splitting of universes is, or what a prediction is, or anything that relates to a real-world experiment. There is no experiment that has ever confirmed any aspect of MWI. The problem with an experimental test is that MWI does not make any predictions.