Scientists believe that light can turn into matter

As unlikely as it is, under certain conditions, a photon can turn into another particle and antiparticle, which has mass. Theoretical physicists, inspired by that idea, checked and found out that the graviton, the hypothetical quantum of gravitational force, can also be transformed into other particles, namely photons. 

Sometimes particles transform into one another through various processes, but a photon, a quantum of energy, does not do this because it has no mass, so it cannot theoretically transform into a particle with mass. However, it becomes possible under certain special conditions. if a high-energy photon passes near the nucleus of an atom, that energy can be converted into an electron-positron pair, that is, two particles with mass, in a process known as "pair creation". It is the main mode of interaction of photons with matter.

Based on this strange phenomenon, physicists from the University of Montreal's McGill University and the Jagiellonian University in Krakow have assumed that gravity can also be transformed into other particles. The much stronger gravitational waves in the early Universe are described by general relativity as a warped manifestation of space-time, which in turn is generated by the distribution of energy within it. But from the point of view of quantum physics, these space-time fluctuations, i.e. gravitational waves, can be interpreted as the propagation of a hypothetical elementary particle that transmits gravity called a graviton.

Gravitons theoretically behave like other fundamental particles, so they can potentially transform into one another. A group of researchers tried to test this hypothesis. They focused on the conditions of the early Universe, when there was no structure (no stars, no galaxies) and when all matter and energy were grouped together in a very dense volume. Under these special conditions (more than 13 billion years ago), gravitational waves should have played an important role in the evolution of our Universe. Gravitational waves predicted by Einstein in 1916. and were first discovered in 2015, they are usually very weak.

They "can move an atom through space smaller than the width of its own nucleus," Live Science wrote. The collision of two black holes results in a tiny displacement, about 10-18 meters in interferometric detectors. Physicists assure that these waves could have been much more powerful in the early Universe. Those primordial gravitational waves must have amplified, causing matter to oscillate along its path. That effect would contribute to the interaction of various elementary particles and the formation of the first components, which would be followed by the first atomic nuclei. But those waves could also have an effect on the surrounding electromagnetic field, raising that radiation to an extremely high energy level, up to the spontaneous generation of photons. The team informed that according to their calculations, they indeed discovered the resonance effect, but it is very weak in vacuum; resonance occurs only in the second resonance layer, so it is very inefficient. In addition, gravitational waves are not long-lasting.

Conversely, resonance could be much stronger in an environment where electromagnetic waves would move much more slowly. In other words, if the early Universe had enough matter and was dense enough to slow down the speed of light, gravitational waves could persist long enough to generate more photons. Therefore, gravity could create light, significantly affecting the formation of matter and the evolution of the Universe.