Formally Defining Wavefunction Branches

LW Meta: This post is (a) about how wavefunction branching explains measurements and why chaotic dynamics don't cause the quantum state to become non-classical-looking (b) the mathematical problem of formally defining wavefunction branches. The former will be familiar to people who've read Eliezer's quantum sequence, but the latter is new to LW to my knowledge! 2.5.4 The Emergence of Classicality 2.5.4.1 In 2.5.2 I left open two questions about quantum mechanics and seemingly-classical reality…