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Physicists are about to attempt the impossible: to turn light into matter

Credits: Pixabay / geralt

It should technically be possible to transform light into matter, at least in theory. In practice however, it’s a little more complicated. More than 84 years after the first theories on the process, certain researchers believe that they will soon be able to do so. 

This is referred to as the Breit-Wheeler process, first described in 1934 by two physicists, Gregory Breit and John A. Wheeler. Breit and Weeler assumed that if you were to collide two photons, or light particles, that this collision would result in the formation of positrons and electrons. You would thus have created matter using only light. But this was purely hypothetical. At the time, Breit and Wheeler believed that it would be impossible to test out this theory, noting that it would be “useless to try and observe the formation of pairs in laboratory experiments”.

However, physicists nowadays appear more optimistic, and in 2014, researchers from the Imperial College of London came up with an experiment. “Take Einstein’s famous equation linking energy and mass: E=mc2, which tells us how much energy is produced when matter is transformed into energy”, explains Steven Rose from the study. “What we are doing is the same thing, but in reverse: transforming energy from photons into matter, or in other words, m = E/c2”.

The experimental set-up, which the team call a “photon-photon collider”, is a new type of experiment involving two very high powered laser beams. Inside a targeted chamber, electrons are fired at a gold plate to produce a first beam of high energy photons. Next, a second high energy laser is beamed into a little gold tube called a hohlraum to create a thermal radiation field. The first beam of photons is then directed through the hohlraum, and the photons coming from both sources collide. If it works, the team will be able to detect the formation of electrons and positrons coming from the collisions.

If this experiment works, it will be more than simply incredible in and of itself: it could also help us better understand the Universe. “When Gregory Breit and John Wheeler suggested the mechanism for the first time in 1934, they used a new theory of interaction between light and matter known by the name of quantum electrodynamics”, explained the researcher Stuart Mangles. “If we can demonstrate this now, we would recreate a process that occurred during the first 100 seconds of the Universe and which is also seen during gamma-ray bursts, the largest explosions in the Universe”. 

We are looking forward to seeing the results! Stay tuned!

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