When lead or gold ions accelerated almost to the speed of light bump into each other in the depths of gas pedals, a quark-gluon plasma, or even a "cocktail" of it seasoned with other particles, is created for fractions of seconds. According to scientists from the IFJ PAN, experimental data indicate that there are still other actors in the arena of events: photons. Their collisions lead to the emission of seemingly redundant particles whose presence could not be explained.