Go read the overcomingbias essay on the Many-Worlds interpretation posted above. (Or is it below?) The short answer is that in the many-worlds interpretation,

Go read the overcomingbias essay on the Many-Worlds interpretation posted above. (Or is it below?) The short answer is that in the many-worlds interpretation, this too is a deterministic process. The total wavefunction of the whole system (atom + observer) evolves deterministically. What isn't deterministic is "your" subjective view of it, but "you" only view a vanishingly small slice of reality. Sorry, that's the best three-sentence explanation I can come up with right now, and I admit it's only a shade better than "trust me, I'm a physicist". But trust me, I'm a physicist.