Abstract This chapter explains the use of wave functions in quantum mechanics in order to develop a preliminary argument for wave function realism, one that is commonly found in the physics and philosophy of physics literature. It distinguishes ontological questions about the status of the wave function from the more discussed measurement problem for quantum mechanics, and explains how wave function realism is an approach to ontology that is compatible with several rival solutions to the measurement problem. The chapter then presents an initial, but not ultimately decisive, argument for wave function realism based on the ubiquity of wave function representations in quantum physics.
Abstract This chapter explains the use of wave functions in quantum mechanics in order to develop a preliminary argument for wave function realism, one that is commonly found in the physics and philosophy of physics literature. It distinguishes ontological questions about the status of the wave function from the more discussed measurement problem for quantum mechanics, and explains how wave function realism is an approach to ontology that is compatible with several rival solutions to the measurement problem. The chapter then presents an initial, but not ultimately decisive, argument for wave function realism based on the ubiquity of wave function representations in quantum physics.
Introduction It is not exaggeration to claim that one of the major divides in the foundations of non-relativistic quantum mechanics derives from the way physicists and philosophers understand the status of the wave function. On the instrumentalist side of the camp, the wave function is regarded as a mere instrument to calculate probabilities that have been established by previous measurement outcomes. On the other “realistic” camp, the wave function is regarded as a new physical entity or a physical field of some sort. While both sides agree about the existence of quantum “particles” (the so-called theoretical entities), and therefore reject the radical agnosticism about them preached by van Fraassen (1980), the various “realistic” (and consequently, instrumentalist) philosophies of quantum mechanics are typically formulated in different, logically independent ways, so their implications need to be further investigated. For instance, on the one hand it seems plausible to claim that a realistic stance about the wave function is not the only way to defend “realism” about quantum theory. One can support a “flash” or a “density-of-stuff ” ontology (two variants of GRW), or an ontology of particles with well-defined positions (as in Bohmian mechanics), as primitive ontologies for observer-independent formulations of quantum mechanics (Allori, Goldstein, Tumulka and Zanghí, 2008). “Primitive ontologies”, as here are understood, are not only a fundamental ground for other ontological posits, but also entail a commitment to something concretely existing in spacetime (see also Allori, 2013). On the other hand, however, it is still debated whether such primitive ontologies can be autonomous from some form of realism about the wave function (Albert, 1996). In order to discuss this problem, we begin with a preliminary clarification of the meaning of “realism” and “instrumentalism” in physics, which are often subject to ideological and abstract discussions that often have little to do with the practice of physics (Section 9.2).
In this paper I wish to connect the recent debate in the philosophy of quantum mechanics concerning the nature of the wave-function to the historical debate in the philosophy of science regarding the tenability of scientific realism. Being realist about quantum mechanics is particularly challenging when focusing on the wave-function. According to the wave-function ontology approach, the wave-function is a concrete physical entity. In contrast, according to an alternative viewpoint, namely the primitive ontology approach, the wave-function does not represent physical entities. In this paper, I argue that the primitive ontology approach can naturally be interpreted as an instance of the so-called ‘explanationism’ realism, which has been proposed as a response to the pessimistic-meta induction argument against scientific realism. If my arguments are sound, then one could conclude that: (1) contrarily to what is commonly though, if explanationism realism is a good response to the pessimistic-meta induction argument, it can be straightforwardly extended also to the quantum domain; (2) the primitive ontology approach is in better shape than the wave-function ontology approach in resisting the pessimistic-meta induction argument against scientific realism.
Abstract What are the ontological implications of quantum theories, that is, what do they tell us about the fundamental objects that make up our world? How should quantum theories make us reevaluate our classical conceptions of the basic constitution of material objects and ourselves? Is there fundamental quantum nonlocality? This book articulates several rival approaches to answering these questions, ultimately defending the wave function realist approach. Wave function realism is a way of interpreting quantum theories so that the central object they describe is the quantum wave function, interpreted as a field in an extremely high-dimensional space. According to this approach, the nonseparability and nonlocality we seem to find in quantum mechanics are ultimately manifestations of a more intuitive, separable, and local picture in higher dimensions.
Abstract This chapter considers and responds to criticism that wave function realism is only plausible as an approach to the interpretation of nonrelativistic quantum mechanics and not relativistic quantum theories and quantum field theories. This critique gains traction as wave function realism has until now been formulated and defended solely within the context of idealized, nonrelativistic quantum mechanics. The chapter considers five such arguments and responds to each. An important lesson is that wave function realists should only adopt the wave-function-in-configuration-space picture as part of an interpretation of an idealized nonrelativistic quantum mechanics. More generally, the space the wave function inhabits will vary as the quantum theory the wave function realist is developing an interpretation of varies. The chapter develops a sketch of what wave function realism looks like in one relativistic context. It then discusses the issue of the interpretation of quantum theories in the limit of physical theorizing.
In this paper, I wish to connect the recent debate in the philosophy of quantum mechanics concerning the nature of the wave function to the historical debate in the philosophy of science regarding the tenability of scientific realism. Advocating realism about quantum mechanics is particularly challenging when focusing on the wave function. According to the wave function ontology approach, the wave function is a concrete physical entity. In contrast, according to an alternative viewpoint, namely the primitive ontology approach, the wave function does not represent physical objects. In this paper, I argue that the primitive ontology approach can naturally be interpreted as an instance of the so-called explanationist realism, which has been proposed as a response to the pessimistic-meta induction argument against scientific realism. If my arguments are sound, then one could conclude that: (1) contrary to what is commonly thought, if explanationism realism is a good response to the pessimistic-meta induction argument, it can be straightforwardly extended also to the quantum domain; (2) the primitive ontology approach is in better shape than the wave function ontology approach in resisting the pessimistic-meta induction argument against scientific realism.
Abstract In quantum mechanics, entangled states are not exotic or rare. Rather, entanglement is the norm and so the metaphysical consequences of entanglement are a central issue for anyone wishing to provide an ontological interpretation of the various formulations of quantum mechanics. This chapter presents the argument for wave function realism from quantum entanglement, which says that wave function realism is necessary if one wants an ontological interpretation that does not conflate distinct quantum states. It explains quantum entanglement and how postulating a wave function in higher dimensions can help to metaphysically ground the phenomenon. The chapter ultimately concludes that the argument from quantum entanglement fails as there are several rival positions that can also explain quantum entanglement and recover the distinctions between different entangled states. These include the primitive ontology approach, various other holisms, ontic structural realism, spacetime state realism, and the multi-field approach.