Quantum randomness is fundamentally random, unless you believe in hidden-variable theories, superdeterminism, or something something Bell’s theorem loopholes.
This is true for both shut-up-and-calculate QM and for MWI; the difference is whether the universe is random, or whether the “branch” that your subjective experience ends up on is random. In the latter MWI case, I think any observer looking at the two clones Earths would still see divergence, because an observer is unable to somehow probe the universal wavefunction and see the deterministic evolution of wavefunctions or whatever anyway.
There’s a separate question of whether you can “see” this randomness, and thus whether quantum randomness even matters. The answer is really yes. As one example, mutations can be caused by cosmic rays. Maybe an extremely fit genotype came to be because of a cosmic ray, that happened to come in the right direction due to the randomness from pion decay in the upper atmosphere. That would be a major macroscopic deviation that would happen over generations. There are probably many other such things.
Also, quantum theory forbids wavefunction clones, so the initial state of your two Earths would already be different (different different or different Everettian branches). This is my understanding of the no-cloning theorem, at least.
Quantum randomness is fundamentally random, unless you believe in hidden-variable theories, superdeterminism, or something something Bell’s theorem loopholes.
This is true for both shut-up-and-calculate QM and for MWI; the difference is whether the universe is random, or whether the “branch” that your subjective experience ends up on is random. In the latter MWI case, I think any observer looking at the two clones Earths would still see divergence, because an observer is unable to somehow probe the universal wavefunction and see the deterministic evolution of wavefunctions or whatever anyway.
There’s a separate question of whether you can “see” this randomness, and thus whether quantum randomness even matters. The answer is really yes. As one example, mutations can be caused by cosmic rays. Maybe an extremely fit genotype came to be because of a cosmic ray, that happened to come in the right direction due to the randomness from pion decay in the upper atmosphere. That would be a major macroscopic deviation that would happen over generations. There are probably many other such things.
Also, quantum theory forbids wavefunction clones, so the initial state of your two Earths would already be different (different different or different Everettian branches). This is my understanding of the no-cloning theorem, at least.