The Large Hadron Collider (LHC) is like an immensely powerful kitchen, designed to cook up some of the rarest and hottest recipes in the universe, like the quark–gluon plasma, a state of matter known to have existed shortly after the Big Bang. While the LHC mostly collides protons, once a year it collides heavy ions—such as lead nuclei—a key ingredient for preparing this primordial soup.