About this project
What this is
A connected set of essays that teaches the basics of quantum mechanics to an adult returning to physics. Each essay answers one concrete question with enough mathematics to answer it, restores the tools it uses in short reminders, works one example with real numbers, and puts longer derivations in optional fold-outs that later essays never depend on. The sixteen core essays and the four optional essays on relativity and the Dirac equation are all written in this form.
The site began as a side-by-side comparison of four classic textbooks. That comparison is no longer the organising principle. The books survive as short, checked "Further reading" notes at the end of each essay, listed below by edition.
Editions
| Book | Edition referenced |
|---|---|
| Max Born, Atomic Physics | 8th edition — Dover reprint (1969), English translation of Atomphysik |
| Richard Feynman, Feynman Lectures on Physics, Vol. III | 1964 Caltech edition — linked at feynmanlectures.caltech.edu |
| Richard Feynman, Feynman Lectures on Physics, Vol. I | 1963 Caltech edition — linked at feynmanlectures.caltech.edu (used where photons/blackbody are treated) |
| Landau & Lifshitz, Quantum Mechanics: Non-Relativistic Theory | 2nd ed., revised and enlarged (1965) — Pergamon Press, English translation by J. B. Sykes and J. S. Bell |
| Paul Dirac, The Principles of Quantum Mechanics | 4th edition, revised (1958) — Clarendon Press (Oxford) |
| Albert Einstein, Relativity: The Special and General Theory | 1916 popular exposition — Robert W. Lawson translation (Methuen) — used for Appendix chapters A–C. Public domain: quotation from this source is exempt from the fifteen-word ceiling below (see Content policy). |
Content policy
All prose, worked examples and figures on this site are original. Direct quotations from the four quantum texts are rare and kept short (under fifteen words) with attribution. Derivations, proofs and figures from the books are not reproduced; the derivations, worked examples and figures in the essays are written and generated independently. The one exception is Einstein's Relativity: The Special and General Theory (1916), which is in the public domain; quotation from it in the Appendix is not bound by the fifteen-word ceiling, though the same standards of attribution and restraint apply.
Reference verification
Every further-reading pointer has been checked against the edition listed above, at one of two levels: either the section's location and title were confirmed from the book's contents, or the supporting passage itself was read. The project's source ledger records which level applies to each pointer. Pointers that could not be checked have been removed rather than guessed. Numbers in the worked examples are computed by small scripts kept with the site, so they can be re-run.