LHC experiment spots evidence of photons interacting | Science News

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Normally aloof particles of light seen ricocheting off each other

LHC experiment is first direct evidence of photon-on-photon scattering

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11:00am, August 14, 2017
two photons bounce off each other

TRAVELING LIGHT  Particles of light can scatter off one another, a new study suggests. Researchers from the ATLAS experiment (illustrated) at the Large Hadron Collider detected events in which two photons (yellow beams) bounced off each other in collisions of lead nuclei.

Cross two flashlight beams and they pass right through one another. That’s because particles of light, or photons, are mostly antisocial — they don’t interact with each other. But now scientists have spotted evidence of photons bouncing off other photons at the Large Hadron Collider at CERN, the European particle physics lab in Geneva.

“This is a very basic process. It’s never been observed before, and here it is finally emerging from the data,” says theoretical physicist John Ellis of King’s College London who was not involved with the study. Researchers with the ATLAS experiment at the LHC report the result August 14 in Nature Physics.

Because photons have no electric charge, they shouldn’t notice one another’s presence. But there’s an exception to that rule. According to quantum mechanics, photons can briefly transform into transient

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