![Collisions of lead ions are observed by NA49, one of the experiments involved in CERN's heavy–ion programme, providing evidence for the existence of a state of matter that existed just after the Big Bang.](https://cern70.cern/wp-content/uploads/2024/04/9503044_02.jpeg)
A combination of results from several experiments provides evidence for the existence of Quark–gluon plasma (QGP), a state of matter believed to have existed just after the Big Bang. The experiments all measured different aspects of collisions between the nuclei of heavy atoms and a fixed target at the Super Proton Synchrotron (SPS). This result is the culmination of a heavy–ion programme that started in 1986.