Classic theory predicts that the output frequency must be the same as the input one since the electromagnetic wave makes the electron vibrate with same frequency as itself, which then irradiates further waves.
But the output waves are longer because photons are discrete and energy is proportional to frequency:
The formula is exactly that of two relativistic billiard balls colliding.
Compton Scattering by Compton Scattering (2017)
Source. Experiment with a caesium-137 source.L3.3 Compton Scattering by Barton Zwiebach (2017)
Source. Predicts fine structure.
Bibliography:
Dirac equation for the electron and hydrogen Hamiltonian by Barton Zwiebach (2019)
Source. Uses perturbation theory to get to the relativistic corrections of fine structure! Part of MIT 8.06 Quantum Physics III, Spring 2018 by Barton ZwiebachHow To Solve The Dirac Equation For The Hydrogen Atom | Relativistic Quantum Mechanics by Dietterich Labs (2018)
Source. MIT 8.06 Quantum Physics III, Spring 2018 by Barton Zwiebach Updated 2025-05-29 +Created 1970-01-01
Instructor: Barton Zwiebach.
Free material from university courses:
- physics.weber.edu/schroeder/quantum/QuantumBook.pdf (archive) "Notes on Quantum Mechanics" pusbliehd by Daniel V. Schroeder (2019) The author is from from Weber State University.