On the discovery of the classical equations for spin motion in electromagnetic field

TL;DR

This paper clarifies the historical discovery of the classical spin motion equations in electromagnetic fields, emphasizing the contributions of Frenkel and Thomas alongside the BMT equation.

Contribution

It highlights the original derivation of the spin motion equation by Frenkel in 1926, challenging the common attribution solely to Bargmann, Michel, and Telegdi.

Findings

Frenkel first derived the spin motion equation in 1926.

The BMT equation is historically co-discovered by Frenkel and Thomas.

The paper corrects the attribution of the classical spin motion equation.

Abstract

The letter addresses misattribution of the discovery of the classical equation for spin motion in electromagnetic field, known as the BMT equation, named after Bargmann, Michel, and Telegdi. I argue that J. (or Ya.) Frenkel, along with L. H. Thomas, should be considered as a co-discoverer of this equation. He first derived it, in another form, in 1926.