A group of scientists working at the Large Hadron Collider (LHC) at CERN (European Organization for Nuclear Research), during the ATLAS experiment, proved the existence of a phenomenon called light scattering by light. The phenomenon consists in the quantum interaction of two beams of photons, as a result of which one ray of light is somewhat "refracted" by the other, as if they are solid. The article of the researchers was published in the journal Nature Physics, briefly about the discovery tells the publication ScienceAlert.
According to classical concepts, electromagnetic waves pass through each other unhindered. However, in 1936, German physicists Hans Heinrich Euler and Werner Heisenberg predicted that two photons could collide and interact with each other. Under normal conditions, this effect is invisible, but it can be detected using high-energy particles.
Scientists have dispersed the lead nuclei in the accelerator tube to near-light (relativistic) speeds. The positive charge of the atoms deprived of electrons forms an electrostatic field, which at high speeds turns into an electromagnetic field, that is, into a dense cloud of photons. Lead nuclei moving in opposite directions do not interact directly, but in the course of ultra-peripheral collisions, when clouds of particles strike each other. According to the theory, in this case photons from different clouds are scattered on each other, which generates new particles, which must be registered by the ATLAS detector.
In total, the detector recorded four billion different interactions between particles. Scientists have made the necessary selection and identified 13 events consistent with the picture of light scattering in light. At the same time, the share of extraneous processes that create the background and can make the data unreliable was only 2.6 events. The main process parameters, including the cross section (proximity of colliding particles) and invariant mass (the exponent of particles scattering), are consistent with the predictions of the Standard Model.
The Standard Model is a theory that describes all the variety of particles and their interactions. It predicts various subatomic processes and their properties, which are confirmed in experiments at accelerators, including the LHC.
