One year on from the first-ever collisions of oxygen at the Large Hadron Collider (LHC), the main LHC Collaborations – ALICE, ATLAS, CMS and LHCb – have each reported signs of the state of matter known as quark–gluon plasma (QGP) originating from these collisions.

QGP is a state of matter that forms under intense pressure and at temperatures over 100 000 times hotter than the centre of the Sun. Under these extreme conditions, composite particles break down into quarks and the gluons that ordinarily hold them together. Scientists believe that this was the state of the Universe in the first millionths of a second after the Big Bang...

It was previously thought that colliding heavy ions such as lead – which is over 200 times heavier than the protons typically collided at the LHC – was the only way to create the conditions necessary to form QGP. But recently this premise has been thoroughly challenged, including earlier this year when the ALICE Collaboration, which specialises in the study of this extreme state of matter, reported a new sign of QGP from proton–proton and proton–lead collisions. And last year, the LHC Collaborations opened up a new probe of QGP when they found the first hints of QGP from oxygen–oxygen collisions. Now, having searched even more deeply, the LHC experiments have seen multiple signs of QGP formation in oxygen–oxygen and neon–neon collisions...