Comment on "Magnetic moments in the Poynting theorem, Maxwell equations, Dirac equation, and QED"

TL;DR

This paper critically examines a previous claim about magnetic moments and demonstrates that Maxwell's equations and Poynting's theorem remain valid without modification for magnetic dipoles, correcting the earlier errors.

Contribution

The paper refutes prior claims of necessary modifications to Maxwell's equations and Poynting's theorem for magnetic dipoles, clarifying their universal applicability.

Findings

Previous claims of modifications are based on critical errors.

Maxwell's equations hold for magnetic dipoles as for other charge-current distributions.

Poynting's theorem remains valid without changes for magnetic moments.

Abstract

The paper ``Magnetic moments in the Poynting theorem, Maxwell equations, Dirac equation, and QED", arXiv:2501.02022, by Peter J. Mohr, purports to show that Maxwell's equation, $\mathbf{\nabla}\cdot{\bf B}=0$, and Poynting's theorem require significant modications for the $\bf B$ field of a magnetic dipole. We show here that, because of critical errors in the paper, these claims are false, and that Maxwell's equation and the Poynting theorem are the same for a magnetic moment as for any other charge-current distribution.