04 / RELATIVISTIC QM
Klein–Gordon &
Dirac equations
From relativistic energy to spinors. My handwritten derivations of the Klein–Gordon and Dirac equations, followed by a worked example of a free electron.
4 handwritten pages + 3 typed pages of corrections and context. The original handwriting is preserved; the added appendix was prepared with AI assistance.
What's in the added pages?
- The mass term in the covariant derivation, and the momentum used in the electron example.
- Probability currents, plane-wave normalization and what the spinor components mean.
- Lorentz covariance, chirality, the massless limit and the step toward second quantization.
Includes references to David Tong's QFT notes and MIT lecture notes. These are working study notes, with room to revisit.
Go to the appendix (PDF, opens in a new tab)