Notes on electromagnetic theory — where the classical description ends, where the quantum one begins, and what the potentials are doing in between.
This site collects short technical essays on classical field theory and its quantum continuation: the quaternionic origins of Maxwell’s equations, gauge freedom and what it does and doesn’t mean, the Aharonov–Bohm effect and the status of the potentials, linear response in conducting matter, and a number of questions that were once actively debated and have since fallen out of the textbooks.
Everything here is written for readers who want the reasoning, not the conclusion. Sources are cited; open questions are marked as open.
The articles
Each piece stands on its own and can be read in any order. They are short, they carry their sources, and negative results are reported as prominently as positive ones — often they are the more useful half.
The full list, grouped by subject, is under Articles. By category:
- Classical Electrodynamics (5)
- Forgotten Topics (3)
- History of Physics (3)
- Mathematical Methods (4)
- Quantum & Gauge (3)
Corrections, objections and suggestions are welcome — in the comments under each article, or by email; the address is at the foot of every page.