## La mécanique ondulatoire et la structure atomique de la matière et du rayonnement [Wave mechanics and the atomic structure of matter and of radiation]

*"But if one does not wish to invoke the principle of the double solution, it is acceptable to adopt the following point of view: one will assume the existence, as distinct realities, of the material point and of the continuous wave represented by the function psi, and one will take it as a postulate that the motion of the point is determined as a function of the phase of the wave by the equation (2.51). One then conceives the continuous wave as guiding the motion of the particle. It is a pilot wave." -de Broglie, “La mécanique ondulatoire et la structure atomique...”
"In the last number of the Journal de Physique, a paper by de Broglie has appeared... de Broglie attempts here to reconcile the full determinism of physical processes with the dualism between waves and corpuscles... Even if this paper by de Broglie is off the mark (and I hope that actually), still it is very rich in ideas and very sharp, and on a much higher level than the childish papers by Schrödinger, who even today still thinks he may... abolish material points." -Pauli, in a letter to Bohr, 6 August 1927*

FIRST EDITION IN RARE ORIGINAL WRAPPERS of the presentation of de Broglie’s highly influential “pilot-wave” interpretation of quantum mechanics.

"What we now know as pilot-wave theory first appears in a paper by de Broglie (1927) entitled 'Wave mechanics and the atomic structure of matter and of radiation', which was published in

*Journal de Physique*in May 1927… In 'Structure', de Broglie presents a theory of particles as moving singularities. It is argued, on the basis of certain assumptions, that the equations of what we now call pilot-wave dynamics will emerge from this theory. At the end of the paper de Broglie proposes, as a provisional theory, simply taking the equations of pilot-wave dynamics as given, without trying to derive them from something deeper. It is this last, provisional theory that de Broglie presents a few months later at the fifth Solvay conference…” (Bacciagaluppi and Valentini,

*Quantum Theory at the Crossroads*).

“In October 1927, some of the greatest minds in physics gathered for the Fifth Solvay International Conference to debate the troubling implications of the then-nascent theory of quantum mechanics. A particularly contentious topic was the perplexing ‘wave-particle duality,’ in which objects we typically think of as particles—like photons and electrons—exhibit wave-like properties as well, and things we think of as waves, like light, sometimes behave like particles.

“The French physicist Louis de Broglie proposed a means by which a photon or electron could behave like both a particle and a wave, complementary aspects of the same phenomenon. He reasoned that the particles could be carried along by what he dubbed ‘pilot waves’—fluid-like ripples in space and time—much like a buoys bobbing along with the tide.

“Quantum mechanics seeks to describe nature at the level of individual atoms and the particles that comprise them. But when physicists began delving into this strange new realm at the dawn of the 20th century, they discovered that the old, deterministic laws of classical physics no longer apply at that scale. Instead, uncertainty reigns supreme. It is a world governed by probabilities, and many physicists found this disquieting, to say the least...

“De Broglie’s alternative pilot wave theory was an attempt to restore [the] underlying solid reality. Instead of the wave function, de Broglie’s pilot wave theory employs two equations, one describing an actual wave and the other describing the path of an actual particle and how it interacts with, and is guided by, the wave equation. It is deterministic, like a classical coin flip. In principle, at least, we can glean sufficient information to plot a particle’s path, something that is not allowed in Bohr’s interpretation of quantum mechanics” (Jennifer Ouellette, “Quantum Physicists Catch a Pilot Wave”,

*Nova: The Nature of Reality*).

In 1952 David Bohm rediscovered de Broglie’s work and further developed it. It is now known as the de Broglie-Bohm theory and is a much-debated approach to quantum mechanics today.

IN: Journal de Physique et le Radium, Ser. VI, Vol. VIII, No. 5, May 1927. Octavo, original printed wrappers; custom box. Some chips to wrappers and wear to spine; rear wrapper neatly detached along joint, but now held in place by removable mylar. RARE.

Price: $4,800 .