Huygens’s wave propagation principle and the Mott problem

It is important to recognize the role of the “backward wave” in “wave propagation”. The role of the complement cannot be disregarded…it must be understood. Here are some links to papers that deal with the issue as a physical principle.

Huygens’ Principle geometric derivation and elimination of the wake and backward wave
Forrest L. Anderson

https://www.nature.com/articles/s41598-021-99049-7

Abstract:

Huygens’ Principle (1678) implies that every point on a wave front serves as a source of secondary wavelets, and the new wave front is the tangential surface to all the secondary wavelets. But two problems arise: portions of wavelets that exist outside of the new wave front combine to form a wake. Also there are two tangential surfaces so wave fronts are propagated in both the forward and backward directions. These problems have not previously been resolved by using a geometrical theory with impulsive wavelets that are in harmony with Huygens’ geometrical description. Doing so would provide deeper understanding of and greater intuition into wave propagation, in addition to providing a new model for wave propagation analysis. The interpretation, developed here, of Huygens’
geometrical construction shows Huygens’ Principle to be correct: as for the wake, the Huygens’ wavelets disappear when combined except where they contact their common tangent surfaces, the new propagating wave fronts. As for the backward wave, a source propagates both a forward wave and a backward wave when it is stationary, but it propagates only the forward wave front when it is advancing with a speed equal to the propagation speed of the wave fronts.

Huygens’s wave propagation principle corrected David A. B. Miller

Click to access 146.pdf

Mott’s original paper

https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.1929.0205

A nice short answer to a question about the Mott problem…

https://www.quora.com/In-quantum-mechanics-what-is-the-Mott-problem

Mott Problem: Formulation, Interpretation, and Implications
Miriam Diamond

Click to access mott.pdf

There are lots more…just Google “the Mott problem”