This contribution aims to offer a coherent ontology for the Aristotelian Pilot-wave theory. In the first part, I explain the twofold role of the wave function, which, on one hand, represents a field that performs a force on the particles, and, on the other hand, generates the possible trajectories of the particles. I point out how these two roles generate a tension in Valentini’s ontological account of the wave-field and I propose a way to solve this tension, by reformulating the concept of force as active dispositions of the field. In the last part, I defend the notion of force in Valentini’s pilot-wave theory and I discuss the problem of the violation of the third Newtonian law that the theory has to face.
This contribution aims to offer a coherent ontology for the Aristotelian Pilot-wave theory. In the first part, I explain the twofold role of the wave function, which, on one hand, represents a field that performs a force on the particles, and, on the other hand, generates the possible trajectories of the particles. I point out how these two roles generate a tension in Valentini’s ontological account of the wave-field and I propose a way to solve this tension, by reformulating the concept of force as active dispositions of the field. In the last part, I defend the notion of force in Valentini’s pilot-wave theory and I discuss the problem of the violation of the third Newtonian law that the theory has to face.
Bohmian Mechanics (Dürr et al. 1992) and the Pilot Wave theory (Valentini 1991) provide two opposite understandings of what guides the particles. On one hand there is a universal nomological wave-function (Dürr et al. 1997), which dictates the motion of the particles (the primitive ontology), on the other hand there is universal Ψ-field, which acts causally on the particle configuration. Both views have to face many challenges. Among them, the nomological interpretation has to account for how the law – the wave-function - is grounded in the primitive ontology (Esfeld 2013), while the causal interpretation has to solve the problem of how an entity in configuration space can be the cause of a motion in physical space (Esfeld et al. 2013). Considering now the problem of the nomological interpretation, the anchorage of the lawlike wave-function to the primitive ontology was provided by Esfeld, who recently proposed to ground the wave-function in a dispositional property instantiated by all the particles taken as a whole (Esfeld et al. 2013). However, two challenges come here: the first concerns the tension in deciding whether or not the dispositional property should be part of the primitive ontology, and the second concerns the weak explanatory power that the dispositionalist account can provide. The debate has led to an interesting structuralist account (Esfeld et al. 2015, Lam 2015), which is to regard the wave-function as a modal structure, which relates all the particles of the universe in a non-local fashion, hence explaining the dynamics of the particles. Regarding the problems of the causal interpretation, Valentini thinks of the Ψ- field not as concrete and as physical as an electromagnetic field, but as a ‘more abstract field’ (Valentini 1991): in fact, it lives in configuration space and for this reason it does not admit test particles. Moreover, he does not regard it as an efficient cause of the particle configuration, but as a formal cause, in an Aristotelian-Thomistic sense, in such a way that it should be considered as a guiding form. According to his Aristotelian view of formal cause, the motion is the fulfilling of what exists potentially, which is represented by the Ψ-field (Valentini 1991). The reason why the Ψ-field should be regarded as a real ‘guiding form’ is twofold: on one hand it is its form that determines the trajectories of the particles, on the other hand, its role is to storage formal information between the particles. After having analyzed both representations of the ‘Ψ’, as a modal structure in the first scenario, and as a formal cause in the second, I will claim that, if we hold Esfeld’s account of the universal wave-function in Bohmian Mechanics and the characterization by Valentini of the pilot wave, then the two views do not differ as much as it is normally thought, because in both the wave-function is regarded as a dynamical structure. This reconciliation is especially achieved if we consider that, being all the particles identical, both theories may be reformulated in a reduced-configuration space.
Abstract This introductory chapter reviews the main steps in the history of the pilot-wave theory from its inception to the present day, as well as the major philosophical discussions revolving around this theoretical framework. The first part of this essay begins with a discussion of de Broglie’ key ideas leading to the first formulation of the pilot-wave theory in 1924, followed by a detailed analysis of David Bohm’s rediscovery of this framework in 1952 along with the generalizations of his causal interpretation to the Pauli and Dirac theories. Moreover, the second renaissance of the pilot-wave theory is considered. Here I focus on the works of Hiley, Dewdney, Philippidis, Holland and other collaborators of Bohm who provided decisive contributions to the causal interpretation between the late 1970s and the 1980s. This part is concluded taking into account recent developments of the pilot-wave perspective, with particular attention to the approaches of Dürr, Goldstein, Zanghì and Valentini. The second part of the essay discusses in detail some of the main metaphysical debates concerning the ontology of this interpretative framework, as for instance the status of the wave function, the various notions of “particle” employed by various authors, as well as the meaning of quantum operators and contextuality in the de Broglie-Bohm theory. In addition, also the notion of primitive ontology is briefly introduced. Finally, the third part of this introduction illustrates the book chapters, guiding the reader into the various contents of the volume.
The original version of the de Broglie-Bohm pilot-wave theory, also called Bohmian mechanics, attempted to treat the wave function or pilot wave as a part of the physical ontology of nature. More recent versions of the de Broglie-Bohm theory appearing in the last few decades have tried to regard the pilot wave instead as an aspect of the theory's nomology, or dynamical laws. This paper argues that neither of these views is correct, and that the de Broglie-Bohm pilot wave is best understood as a collection of latent variables in the sense of a hidden Markov model, a construct that was not available when de Broglie and Bohm originally formulated what became their pilot-wave theory. This paper also discusses several other challenges for the ontological view of the pilot wave. One such challenge is due to Foldy-Wouthuysen gauge transformations, which connect up with the Deotto-Ghirardi ambiguity in the de Broglie-Bohm theory. Another challenge arises from the freedom to carry out canonical transformations in the wave function's own notion of phase space, as defined by Strocchi and Heslot.
I combine the idea of a primitive ontology with the metaphysics of laws of nature. In so doing, I examine the theoretical entities that are postulated in Newtonian mechanics, classical electrodynamics, and the de Broglie–Bohm quantum theory. I argue that the existence of mass, forces, fields, and the wave-function depends on the status of laws. The three major theories on laws of nature I treat are Humeanism, dispositionalism, and primitivism about laws. I point out that properties are notoriously ignored in debates on primitive ontologies. In fact, I show that properties, both intrinsic and relational, aren’t needed in physics; therefore, I replace the primitive ontology with a primitive stuff ontology, whose elements have no properties. Recently, a debate has started on the ontological status of forces in classical mechanics; I criticize the major positions and present my own idea that focuses on the status of laws of nature. Another hot topic is the status of the wave-function. Here, I develop a new interpretation in the framework of Humeanism that crucially differs from that advocated by David Albert and Barry Loewer, in that our world is not an illusion of a reality in configuration space. In addition, I propose a hitherto unconsidered way in which the wave–function can be construed as a holistic disposition.
The purpose of this paper is to present an overview of recent work on pilot-wave approaches to quantum field theory. In such approaches, systems are not only described by their wave function, as in standard quantum theory, but also by some additional variables. In the non-relativistic pilot-wave theory of deBroglie and Bohm those variables are particle positions. In the context of quantum field theory, there are two natural choices, namely particle positions and fields. The incorporation of those variables makes it possible to provide an objective description of nature in which rather ambiguous notions such as 'measurement' and 'observer' play no fundamental role. As such, the theory is free of the conceptual difficulties, such as the measurement problem, that plague standard quantum theory.