At very high energies, the collision of massive atomic nuclei in an accelerator generates hundreds or even thousands of particles that undergo numerous interactions. Physicists at the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow, Poland, have shown that the course of this complex process can be represented by a surprisingly simple model: Extremely hot matter moves away from the impact point, stretching along the original flight path in streaks, and the further the streak is from the plane of the collision, the greater its velocity.