How would a photon describe the universe

How light can be converted into matter

In 1934, the physicists Gregory Breit and John Wheeler described a particle reaction in which an electron and its antiparticle, the positron, are created from two photons that collide. This process has not yet been observed in this form. Researchers from Imperial College in London have now developed a new, but so far only theoretical, concept for an experiment in which light can be converted into matter. They published their results in the journal "Nature Photonics".

According to Albert Einstein, mass can be converted into energy and vice versa. If you want to create new particles, the energy used must be at least as large as the mass of the new particles - the exact value can be calculated using Einstein's famous formula. Oliver Pike and his colleagues now considered in which experimental setup one could provide light quanta with the necessary energies. "The experimental implementation would have been possible for a long time, but so far nobody has come up with this idea," says co-author Felix Mackenroth from the Max Planck Institute for Nuclear Physics.

First, so the result, electrons have to be shot at a gold foil. The collisions with the gold nuclei slow down the electrons and give off their energy again in the form of photons, which are a billion times more energetic than visible light. This radiation can be directed into a special container, heated with a laser, which also contains photons. If the high-energy light particles hit a photon in this chamber, an electron-positron pair is created directly, without other mass-laden particles being created in between, as happens in other experiments that have already been carried out. In order to separate and prove these electrons and positrons, the scientists want to use a magnetic field.

Using model calculations, the team was able to show that one photon pulse should be able to generate 1,000 to 100,000 pairs of particles. “As soon as the structure is set up, reliable data should be available within a few months. We are of course already working on the experimental implementation and are waiting for the approval from the large research institutions where the experiment can be carried out ", says Mackenroth and continues:" The newly developed research fields could be immense. We plan to make so-called photon-photon colliders experimentally accessible with the proposed class of experiments. "

These could provide new insights into processes in the early universe, since this is where particle reactions and similar ones took place. If these reactions could be simulated and investigated in the laboratory, this would contribute to an understanding of the history of the creation of the universe.