An Envariance-based Objection to the Many Worlds Interpretation of Quantum Mechanics

In this paper, I argue that there is a problem with the Many Worlds Interpretation of quantum mechanics (MWI). I show this by relying on the notion of envariance. Zurek's work on envariance was intended to strengthen the MWI by providing a non-circular derivation of the Born rule within the MWI framework. However, I will argue that envariance actually undermines the MWI by showing that in many situations, the system-environment terms in the entangled universal quantum state don't correspond to distinct entities as MWI-advocates such as David Wallace claim they do. After making my envariance-based objection to the MWI, I show that three other interpretations—the Relational Quantum Mechanics interpretation, the de Broglie-Bohm (aka the Pilot Wave) interpretation, and the GRW interpretation—do not adopt all the assumptions needed for envariance, and so can sidestep the problem that envariance presents to the MWI. My argument against the MWI is of relevance to the philosophy of middle-sized objects since it highlights a problem with the claim that a multiplicity of middle-sized objects emerge in different worlds from a universal quantum state.