Séminaires du Département de Physique.

Après-midi thématique "Fondements de la Physique" à destination de ses enseignants/chercheurs et étudiants (L3 et masters).

* "Double solution program and de Broglie-Bohm dynamics : An introduction " * by Thomas DURT, Institut Fresnel

**Abstract : **

Louis Victor de Broglie received the physics Noble prize in 1929, at the age of 37 only, “for his discovery of the wave nature of the electron”, that he developed in his Ph.D thesis of 1924, after that his theoretical predictions were confirmed by the US experimentalists Davisson and Germer, who observed for the first time diffraction of

electrons by a crystal. In 1927, he took part to the 5th Solvay Physics Council in Brussels (“Electrons et photons”’) where he proposed a non-standard interpretation of the quantum theory in which particles follow well-defined traject

ories governed by the Schrödinger wave function (also called “pilot wave” in this context), in accordance with the so-called "guidance equation”. This idea was rediscovered and simplified by David Bohm in 1952, and is today known under the label “de Broglie-Bohm dynamics”. This dynamics is classical in the sense that it reintroduces at the quantum level the concept of continuous and deterministic trajectory but it also departs from the classical intuition by several aspects. Although it never was very successful, the de Broglie-Bohm interpretation played a prior role in the recognition of the non-classical (contextual and non-local) features of the quantum theory. It can be seen as an ultimate (and hopeless ?) attempt to interpret the latter in a realistic fashion. In the 21st century, unexpected developments of this approach arose :

- the de Broglie double solution program was revived in the framework of semi-

classical gravity. - chaotic properties of the de Broglie-Bohm dynamics were put in relation with

the concept of quantum equilibrium, and its corollary, quantum non-equilibrium, found potential applications in cosmology. - the wave-particle duality has manifested itself in some quite unexpected places, for instance in hydrodynamics, in the form of so-called “walkers”.

These are vibrating droplets of macroscopic size, visible to the naked eye, that exhibit dynamics strongly resembling that of de Broglie-Bohm.

We aim at providing a first glimpse of this too often ignored approach of the quantum

theory, putting into light its paradoxical implications as well as its intrinsic limitations

Contact : Thomas DURT - thomas.durt@centrale-marseille.fr