What a timely article and comment. I've been watching a lecture series over the last few days about quantum mechanics and the many worlds interpretation. And I have questions.

I may have missed it or didn't understand it when I heard it explained. What underpins the notion that when a particle transitions from a superposed to defined state, the other basis states continue to exist? If they have to continue to exist, then okay many worlds, but why do we think (or know?) they must continue to exist?