And this idea, called the “many worlds” interpretation, raises other problems. Some theorists say it suggests that physicists doing a quantum experiment would find themselves in a random world, such that they would have an equal chance of seeing the bell ring or not ring. But this does not match the well-tested Born rule, which may predict that the bell should ring 70% of the time, for example.
I have no clue how seriously we can take all this. But it doesn’t really matter. I love that respected scientists are looking into it.