Posted: Mar 17, 2019 12:14 pm
The latest research on photon-photon scattering in the proximity of lead ions by the ATLAS group @ CERN:
More @ atlas.cern source
The scattered photons in an otherwise empty ATLAS chamber with the Feynman diagram of the interaction at lower right:

ATLAS observes light scattering off light
New result studies photons interacting at high energies
By ATLAS Collaboration, 17th March 2019
Light-by-light scattering is a very rare phenomenon in which two photons – particles of light – interact, producing again a pair of photons. This process was among the earliest predictions of quantum electrodynamics (QED), the quantum theory of electromagnetism, and is forbidden in classical physics (such as Maxwell's theory of electrodynamics).
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More @ atlas.cern source
The scattered photons in an otherwise empty ATLAS chamber with the Feynman diagram of the interaction at lower right:
