Fotonitörmäyksessä

Fotonitörmäyksessä, sometimes referred to as photon-photon scattering or light-by-light scattering, is a quantum electrodynamics (QED) process where two photons interact directly with each other. Unlike classical electromagnetism, where photons are considered to propagate without interacting, QED predicts that this interaction is possible through the temporary formation of virtual particle-antiparticle pairs, most commonly electron-positron pairs.

This process is extremely rare and has a very low probability of occurring. The virtual particles mediate the interaction, effectively acting as a bridge between the two photons. The energy of the interacting photons must be sufficiently high for this process to become observable. For instance, if the photons have enough energy, they can create real particle-antiparticle pairs, which is a related but distinct phenomenon known as Breit's formula.

Direct observation of fotonitörmäyksessä has been a significant experimental challenge. However, evidence for this phenomenon has been indirectly observed in high-energy particle collisions. For example, at the Large Hadron Collider (LHC), experiments have detected events consistent with light-by-light scattering. These observations confirm a key prediction of QED and provide a unique window into the fundamental interactions of light. The study of fotonitörmäyksessä is important for testing the validity of QED at high energies and for exploring potential new physics beyond the Standard Model.