Engineers operating the Large Hadron Collider (LHC) near the Swiss city of Geneva have smashed together subatomic beams in the machine for the first time.
Cheers broke out in the control room when beams of subatomic particles sent in opposite directions around the giant underground tunnel collided.
The step was hailed by those working on the huge physics experiment. "It's a great achievement to have come this far in so short a time," said Rolf Heuer, director-general of the European Organisation for Nuclear Research (Cern).
"But we need to keep a sense of perspective - there's still much to do before we can start the LHC physics programme
The low-energy collisions came after researchers circulated two beams simultaneously in the LHC's 27km-long tunnel earlier on Monday.
The LHC, the world's largest machine, will smash together beams of protons in order to create similar conditions to those present moments after the Big Bang and, hopefully, shed light on the cosmos.
