A seemingly impossible proof of the elastic collision of photons could soon become a reality. So far it has never been directly observed that two light particles actually collide and then shoot apart again.
Geneva (Switzerland). Physicists report in the Physical Review that the exotic and extremely rare collisions of photons in a particle accelerator at CERN are possible and can soon be detected.
The photons of light are actually loners. They have no mass and cannot influence each other. It is possible for two laser beams to cross each other without being scattered. Today we know that under certain conditions, the photons can interact with each other via a quantum process.
What happens when two photons collide? In theory, an elastic collision can occur, in which the light particles collide like two billiard balls and then jump apart again. However, this process has not yet been observed. It used to be considered impossible for such a collision to be caused. Even an extremely strong light source does not have enough energy for this.
A new analysis by Mariola Klusek-Gawenda and her colleagues shows that these photon collisions are possible in the world’s largest particle accelerator, the so-called Large Hadron Collider (LHC) at CERN near Geneva, and that they can also be detected in the future.
For their study, the researchers calculate the trajectories of the particles that occur whenever lead nuclei form in the LHC and something touches them. Klusek-Gawenda explains that the large electrical charges in the lead nuclei can often lead to the formation of photons. If this process occurs in two nuclei flying close to each other, then they could collide with each other.
Evidence of this is possible in the next few years
The probability of such events is very rare but not impossible. The photons that are produced in this collision could be registered by a large detector in the accelerator based on the calculation of the trajectory and filtered out of the set of events.
Klusek-Gawenda is certain that this collision can actually be observed and verified. She thinks it could be as early as next year. If the researchers are successful, it would be a major step forward for physics , and previously unknown quantum processes could be unveiled through the detection.
