Scientists have hailed a successful switch-on for an enormous experiment which will recreate the conditions a few moments after the Big Bang.
They have now fired two beams of particles called protons around the 27km-long tunnel which houses the Large Hadron Collider (LHC).
The £5bn machine on the Swiss-French border is designed to smash protons together with cataclysmic force.
Scientists hope it will shed light on fundamental questions in physics.
The first – clockwise – beam completed its first circuit of the underground tunnel at just before 0930 BST. The second – anti-clockwise – beam successfully circled the ring after 1400 BST.