FIELD INDEX/2026
Index
01
FIELD DRAWER / 01
Physics.
From reference frames and least action to photonic experiments: working notes that begin with a question and keep the derivation visible.
equations / experiments / explanations
FEATUREDA.01
Notebook · 18 July 2026
Symmetry & the Least Action Principle
A route from Fermat’s principle to Euler–Lagrange equations, and from invariance to Noether’s theorem.
Open field note →ALL ENTRIES
03 notes in this drawerA.01Symmetry & the Least Action PrincipleA route from Fermat’s principle to Euler–Lagrange equations, and from invariance to Noether’s theorem.18 July 2026A.02Reference Frames—and What RemainsWhy inertial frames receive a special name, and what a coordinate velocity can conceal.26 July 2026A.03Ghost Imaging: What the Blur Was Telling UsLab notes on pump focusing, spatial-mode decoherence, and refusing the cleanest-looking data.08 August 2025