It is argued that the many-worlds interpretation is by far the best interpretation of quantum mechanics. The key points of this view are viewing the wave functions of worlds in three dimensions and understanding probability through self-locating uncertainty.
A brief (subjective) description of the state of the art of the many-worlds interpretation of quantum mechanics (MWI) is presented. It is argued that the MWI is the only interpretation which removes action at a distance and randomness from quantum theory. Limitations of the MWI regarding questions of probability which can be legitimately asked are specified. The ontological picture of the MWI as a theory of the universal wave function decomposed into a superposition of world wave functions, the important parts of which are defined in three-dimensional space, is presented from the point of view of our particular branch. Some speculations about misconceptions, which apparently prevent the MWI from being in the consensus, are mentioned.
What is quantum mechanics about? The most natural way to interpret quantum mechanics realistically as a theory about the world might seem to be what is called wave function ontology: the view according to which the wave function mathematically represents in a complete way fundamentally all there is in the world. We argue that: • Strictly speaking, it is not possible to interpret quantum theories as theories about the wave function; • Even if the wave function is supplemented by additional non-ontological structures, there are reasons not to take the resulting theory seriously; • All quantum theories should be regarded as theories in which physical objects are constituted by a primitive ontology. The primitive ontology is mathematically represented in the theory by a mathematical entity in three-dimensional space, or space-time.
Abstract The three major interpretations of quantum mechanics—Bohm, GRW, and many worlds—all treat the wave function as a physical entity. But this entity apparently resides in a high-dimensional configuration space, with three coordinates for each particle in the universe. Some conclude on this basis that the three-dimensionality of the world of experience is an illusion. Others respond by adding three-dimensional ontology to the theory or by reinterpreting the wave function either as a law or as an indirect representation of properties in three-dimensional space. It is argued that the latter possibility makes it unnecessary to postulate either additional ontology or a fundamentally high-dimensional world.
The usual interpretation of the quantum theory is self-consistent, but it involves an assumption that cannot be tested experimentally, viz., that the most complete possible specification of an individual system is in terms of a wave function that determines only probable results of actual measurement processes. The term ‘ontological interpretation’ is sometimes applied to Bohm’s approach, as he set out to tackle the ontological problems of conventional quantum theory. However, the ontological interpretations are strikingly different. In the many worlds view, the differing branches are simultaneously and equally real, whereas Bohm’s inactive channels remain as unmanifested potentialities, with steadily declining likelihoods as more and more irreversible process (like measurement) pile up along the manifest branch. Bohm’s theory serves to illuminate some of the more interesting aspects of quantum theory (its contextuality and nonlocal nature) and demonstrates what is at stake from an ontological point of view.