## 70 years of Bohm’s pilot wave theory

Organization: **Andrea Oldofredi**

This event is a celebration of the 70th year of David Bohm’s papers *A suggested interpretation of the quantum theory in terms of hidden variables Part I & II* published in January 1952 in the prestigious Physical Review, where he proposed the very first alternative formulation of quantum mechanics. These essays not only contributed fundamentally to the interpretational debate which is still ongoing today, but also their content is still widely discussed and studied. In this one-day workshop six scholars whose research is influenced by or based on Bohm’s works will speak about the philosophy, history and physics of the pilot-wave theory and its recent developments.

9h30 – 9h45: *Introduction*

9h45 – 10h45: **Valia Allori **– *Wave-Functionalism*

*Abstract***:** In this paper I present a new perspective for interpreting the wave function in quantum theory as a nonmaterial, non-epistemic, non-representational entity. I endorse a functional view according to which the wave function is defined by its roles in the theory. I argue that this approach shares some similarities with the nomological account of the wave function as well as with the pragmatist and epistemic approaches to quantum theory, while avoiding the major objections of these alternatives.

10h45 – 11h45: **Roderich Tumulka**** –** *A vision for a Bohmian theory of quantum electrodynamics*

*Abstract***: **I outline what a Bohmian theory of particles for photons, electrons, and positrons in Minkowski space-time could look like. On the way, I will talk about multi-time wave functions and relativistic versions of Bohmian mechanics, I will discuss explicit equations, and I will describe the open problems.

12h00 -14h00: Lunch (Cafeteria at the Faculty of Law)

14h00 – 15h00: **Antonio Vassallo** – *On the prospects of a de Broglie-Bohm-Barbour-Bertotti theory*

*Abstract***:** Pure shape dynamics (PSD) is a novel implementation of the relational framework originally proposed by Julian Barbour and Bruno Bertotti. PSD represents a Leibnizian/Machian approach to physics in that it completely describes the dynamical evolution of a physical system without resorting to any structure external to the system itself. This is achieved by casting the system’s dynamics in terms of the geometric properties of an unparametrized curve defined over the appropriate relational configuration space (called *shape space*). In this talk, I will consider how PSD describes a de Broglie-Bohm N-particle system and what metaphysical morals can be drawn from such a description. In particular, I will discuss whether the pilot wave can be “geometrized away” (i.e., mathematically reduced to some geometric features of the system’s dynamical curve in shape space). [Based on joint work with Tim Koslowski and Pedro Naranjo]

15h00 – 16h00: **Olival Freire Jr** – *On the vicissitudes of Bohm’s 1952 interpretation of quantum mechanics*

*Abstract***: **When David Bohm published, in 1952, an interpretation of quantum mechanics in terms of hidden variables he could not foresee the complex fate it would have. Dispute of priorities with Louis de Broglie, a poor reception among most of the physicists, an enthusiastic reception among a few ones, particularly in France, including an alliance with de Broglie, frustration with the reception of this proposal, its abandonment, and a revival of interest in this proposal. After Bohm passed away, the proposal gained its own life with different and competing strands and supporters. Nowadays, one among other possible interpretations of quantum mechanics. What kind of lessons for the practice of science one can draw from this history will be the subject of this presentation.

16h00 – 16h30: Coffee Break

16h30 – 17h30: **Aurélien Drezet** – *Louis de Broglie and David Bohm in perspective: Beyond the pilot-wave theory*

*Abstract***: **One hundred years ago Louis de Broglie introduced his famous wave mechanics which paved the way to modern quantum mechanics. Moreover, in 1927 he subsequently proposed two alternative approaches to the orthodox interpretation of Bohr, Born and Heisenberg: (i) The pilot-wave and (ii) the double solution theories. The most known of these approaches is of course the pilot-wave theory that was rediscovered and developed seventy years ago by David Bohm and many after him. The double solution path has been mostly ignored by physicists and philosophers. In this talk we will review the double solution theory of de Broglie and compare it with the pilot-wave approach. In the end, we will propose a new model where particles are actually localized waves (also named “solitons”) solutions of a non-linear field equation. Potentialities and open issues will be emphasized and discussed.

17h30 – 18h30: **Marij van Strien** – *Why Bohm was never a determinist*

*Abstract:* David Bohm’s interpretation of quantum mechanics has mostly become known as a fully deterministic account of quantum mechanics. For this reason, it has often been thought that Bohm’s aim was to restore the determinism of classical physics; and after he published this interpretation in 1953, he was often criticized as conservative and unwilling to accept the radical implications of quantum physics. However, although Bohm’s proposal from 1953 does indeed have the feature of being deterministic, for Bohm this was never the main point. In fact, in other texts which he published shortly before and after, as well as in correspondence, he argued that the assumption that nature is deterministic is unjustified, and that we should abandon the idea of a strict determinism. His aim was a different one: to develop an understandable theory of quantum mechanics. In this talk, I will examine Bohm’s ideas on determinism and causality. I will show that Bohm aimed to develop a notion of causality different from determinism, and that he found resources for this in dialectical materialism. Furthermore, I will argue that concerns over determinism generally have played a less central role in the opposition to (the standard interpretation of) quantum mechanics than is often thought.

The poster of the conference can be found here and the flyer containing full details about the program here.

Should you have any question please contact **Andrea Oldofredi** at aoldofredi@letras.ulisboa.pt