# Feynman's different approach to electromagnetism

## TL;DR

This paper uncovers and analyzes Feynman's unique 1960s approach to deriving electromagnetism, emphasizing minimal assumptions and offering a different route to Maxwell's equations and the Lorentz force, with implications for physics education.

## Contribution

It presents a previously unpublished Feynman derivation of electromagnetism that minimizes physical assumptions and offers an alternative pedagogical perspective.

## Key findings

- Homogeneous Maxwell's equations derived without Coulomb's law
- Lorentz force derived from linearity and relativistic invariance
- Approach offers historical and didactical insights

## Abstract

We discuss a previously unpublished description of electromagnetism outlined by Richard P. Feynman in the 1960s in five handwritten pages, recently uncovered among his papers, and partly developed in later lectures. Though similar to the existing approaches deriving electromagnetism from special relativity, the present one extends a long way towards the derivation of Maxwell's equations with minimal physical assumptions. In particular, without postulating Coulomb's law, homogeneous Maxwell's equations are written down by following a route different from the standard one, i.e. first introducing electromagnetic potentials in order to write down a relativistic invariant action, which is just the inverse approach to the usual one. Also, Feynman's derivation of the Lorentz force exclusively follows from its linearity in the charge velocity and from relativistic invariance. Going further, i.e. adding the inhomogeneous Maxwell's equations, requires some more physical input, and can be done by just following conventional lines, hence this task was not pursued here. Despite its incompleteness, this way of proceeding is of great historical and epistemological significance. We also comment about its possible relevance to didactics, as an interesting supplement to usual treatments.