fotonfotonsamverkan
fotonfotonsamverkan refers to the interaction between two photons, a process that is forbidden in classical electrodynamics but permitted in quantum electrodynamics (QED). In this framework, the interaction proceeds via virtual electron–positron pairs that temporarily emerge due to vacuum fluctuations. The lowest–order contribution to photon–photon scattering is encoded in the Euler–Heisenberg effective action, which describes nonlinear corrections to Maxwell’s equations at energies much lower than the electron mass.
The cross‑section for photon–photon scattering is extremely small; for visible light photons the predicted value is
Besides elastic scattering, photon–photon interactions give rise to phenomena such as photon splitting, photon merging, and
Theoretical investigations extend beyond QED, exploring photon–photon interactions in theories with extra dimensions, supersymmetry, or non‑commutative