If you aim a very powerful laser at a piece of foam, the light can give birth to a pair of particles: an electron and a positron. A positron is like an electron, but with a positive charge. Yet capturing that moment had long been elusive: the newborn particles got lost in the noise, like a whisper in a crowd.
It turns out that the plasma created by the laser helps on its own. Inside it, a magnetic field emerges, twisted like a funnel. This funnel catches the positrons and sends them back, toward the beam. Behind it, things are much quieter, making the particles easier to detect. The funnel also squeezes them into a narrow stream, like a hand gathering scattered beads.
To produce more positrons, the target is made of two layers: first a low-density foam, then a dense one. In the sparse layer, the laser has time to create the funnel, while in the dense layer many pairs are born. Calculations show that the signal becomes hundreds of times stronger than before. Such an experiment can already be run on large laser facilities. If it works, scientists will for the first time see light directly turning into matter.
Positrons born in the plasma are turned 180 degrees and fly toward the laser beam, like swimmers carried back to shore by a current.
The idea of creating matter from light resembles science fiction plots, for example, in Arthur C. Clarke's novel 'The Light of Other Days', where light is used to create matter. In reality, the Breit-Wheeler process is the literal conversion of photon energy into particle mass.