Postulates and measurements in Everett's Quantum Mechanics

Abstract

Everett's Relative State Interpretation (aka Many Worlds Interpretation) has gained increasing interest due to the progress understanding the role of decoherence. In order to fulfill its promise as an intellectually economic realistic description of the physical world, two postulates are formulated. In short they are 1) for a system with continuous coordinates $\mathbf x$, discrete variable $j$, and state $\psi_j(\mathbf x)$, the density $\rho_j(x)=|\psi_j(x)|^2$ gives the distribution of the location of the system with the respect to the variables $x$ and $j$; 2) an equation of motion for the state $i\hbar \partial_t \psi = H\psi$. The contents of the standard (Copenhagen) postulates are derived including the quantum probabilities (Born's rule).