It’s just assumed that there’s a better reason than that one universe ceases to exist.
“One universe ceases to exist” doesn’t explain why the universes survive with that probability either.
This was one of the points raised in the QP sequence. You can’t say “MWI doesn’t explain these probabilities” as evidence for Copenhagen, because Copenhagen doesn’t explain them either.
(I don’t actually know the physics, I’m just repeating the teacher’s password.)
“One universe ceases to exist” doesn’t explain why the universes survive with that probability either.
This was one of the points raised in the QP sequence. You can’t say “MWI doesn’t explain these probabilities” as evidence for Copenhagen, because Copenhagen doesn’t explain them either.
(I don’t actually know the physics, I’m just repeating the teacher’s password.)