 While Everett understood decoherence considerations, he did not believe that they rendered the detection alternative measurement records impossible. Indeed, as indicated in his discussion of the Wigner’s Friend story above, Everett held that it was always in principle possible to measure an observable that would detect an alternative post-measurement branch, and it was this that he used to argue the other direction. It is precisely because the linear dynamics requires that all branches of the global wave function are at least in principle detectable that pure wave mechanics requires that all branches are equal real.