In an experiment on the Franco-Swiss border conducted on Nov. 7, scientists managed to create temperatures a million times hotter than those at the centre of the sun and create a mini-Big Bang by smashing together lead ions instead of protons, Reuters reports. The Large Hadron Collider, the world’s highest-energy particle accelerator is kept in a 27-km long circular tunnel underground near Geneva, and has been colliding protons to learn more about how the universe was created. For the next four weeks, scientists will analyze data from lead ion collisions to learn more about the plasma the universe was made of, 13.7 billion years ago, for just a millionth of a second after the Big Bang. The collisions generated the highest temperatures and densities ever produced in an experiment. At those temperatures, protons and neutrons (which make up the nuclei of atoms) melt to create a soup of subatomic particles called quark-gluon plasma, which is believed to have existed just after the Big Bang.