Pilot Wave - History

History

In his 1926 paper, Max Born suggested that the wave function of Schrödinger's wave equation represents the probability density of finding a particle.

From this idea, de Broglie developed the Pilot Wave theory, and worked out a function for the guiding wave. Initially, de Broglie proposed a double solution approach, in which the quantum object consists of a physical wave (u-wave) in real space which has a spherical singular region that gives rise to particle-like behaviour; in this initial form of his theory he did not have to postulate the existence of a quantum particle. He later formulated it as a theory in which a particle is accompanied by a pilot wave. He presented the Pilot Wave theory at the 1927 Solvay Conference. However, Wolfgang Pauli raised an objection to it at the conference, saying that it did not deal properly with the case of inelastic scattering. De Broglie was not able to find a response to this objection, and he and Born abandoned the pilot-wave approach. Unlike David Bohm, de Broglie did not complete his theory to encompass the many-particle case.

Later, in 1932, John von Neumann published a paper claiming to prove that all hidden variable theories were impossible. (A result found to be flawed by Grete Hermann three years later, though this went unnoticed by the physics community for over fifty years). However, in 1952, David Bohm, dissatisfied with the prevailing orthodoxy, rediscovered de Broglie's Pilot Wave theory. Bohm developed Pilot Wave Theory into what is now called the De Broglie-Bohm theory.

The de Broglie-Bohm theory itself might have gone unnoticed by most physicists, if it had not been championed by John Bell, who also countered the objections to it. In 1987, John Bell rediscovered Grete Hermann's work, and thus showed the physics community that Pauli's and von Neumann's objections really only showed that the Pilot Wave theory did not have locality; in fact, no quantum-mechanical theories have locality, so these objections did not invalidate the Pilot Wave theory.

The de Broglie-Bohm theory is now considered by some to be a valid challenge to the prevailing orthodoxy of the Copenhagen Interpretation, but it remains controversial.

Yves Couder and co-workers recently discovered a macroscopic pilot wave system in the form of walking droplets. This system exhibits behaviour of a pilot wave, heretofore considered to be reserved to microscopic phenomena.