Demystifying the multiverse
- 223 Downloads
Superpositions are the characteristic feature of quantum mechanics. Schrödinger’s cat, to take a familiar example, is supposed to be in a superposition of states: one corresponding to being alive, the other corresponding to being dead. This presents a conceptual difficulty: how can a cat be both alive and dead? And it presents an empirical difficulty: when we observe cats, they always appear to be in definite states. The Everettian solution to these problems (introduced by Hugh Everett III in his Princeton doctoral thesis of 1957) is intriguingly simple: macroscopic superpositions are interpreted not as indeterminacy but as multiplicity. Rather than a single cat in an indeterminate state, Everettians recognize multiple cats, each in a determinate state, and multiple observers, each of which observes a cat in a determinate state.
Given the prominence (some would say notoriety) of the Everett interpretation of quantum mechanics in physics, and its enthusiastic reception in popular...