Scientists say they have succeeded in recreating conditions shortly after the Big Bang by switching the particles used for collisions from protons to much heavier lead ions.
A spokeswoman for the European Organization for Nuclear Research (Cern) outside Geneva says the Large Hadron Collider, the world's largest atom smasher, recorded its first lead ion collisions on Sunday.
Barbara Warmbein said on Monday researchers were trying to detect a thick soup of matter called "quark-gluon plasma" in the hope of gaining a deeper insight into how the universe began.
Warmbein said it would likely be months, if not years, before scientists made significant new discoveries.
swissinfo.ch and agencies