> more dimensions to include many worlds, I suppose? There is no spacetime model of many worlds at all, as far as I know. Many worlds as an interpretation of Q

> more dimensions to include many worlds, I suppose? There is no spacetime model of many worlds at all, as far as I know. Many worlds as an interpretation of QM is based on non-relativistic QM. The "space" in which quantum states "live" is not spacetime but Hilbert space. "Many worlds" is really a misnomer in the sense that there is only one quantum state in Hilbert space. But quantum states in Hilbert space can have relationships to ordinary space that are not at all like those in classical physics: for example, a single quantum state can describe a system containing multiple entangled particles that are spatially separated; in such a state no particle by itself has any definite state at all (which is impossible in classical physics). That is true regardless of which QM interpretation you adopt.