Quantum Electrodynamics (QED)
The relativistic quantum field theory describing how light (photons) and charged matter (electrons/positrons) interact.
Governing formula
L_QED = ψ̄ (i γ^μ D_μ - m) ψ - ¼ F_μν F^μν
SI unit
Relativistic Quantum Field
In depth
Developed by Feynman, Schwinger, and Tomonaga, QED treats electromagnetic force as the exchange of virtual photons between charged particles, making predictions (such as electron anomalous magnetic moment) matching experiment to 10 decimal places.
Examples in the real world
Feynman diagrams calculating electron-positron scattering amplitudes and quantum vacuum polarization corrections.