Is many-worlds a relativistic theory?
for how the more general case is handled with quantum field theory or third quantisation.) The rest of the theory is just working out consequences of the above assumptions. Measurements and observations by a subject on an object are modelled by applying the wave equation to the joint subject-object system. Some consequences are: 1) That each measurement causes a decomposition or decoherence of the universal wavefunction into non-interacting and mostly non- interfering branches, histories or worlds.
