Every news outlet today is abuzz with news that the first proton bunches completed an entire round at the Large Hadron Collider in Geneva today, probably the least arbitrary point in the long switch on procedure to celebrate that the LHC is now in business. Now that the physicists at CERN know they can circulate a beam in one direction, the next steps will be to circulate a second beam in the opposite direction at the same time, collide the beams in one of the detectors and then to slowly ramp up the energy to 7 TeV.
The LHC succeeds the LEP or Large Electron Positon Collider that stood in the same location for much of the 90s before it was dismantled in 2000 to make way for the LHC. And apparently the LEP’s switch-on did not nearly go as smoothly as the LHC’s:
When LEP2, as the upgraded machine is known, was switched on, beams of electrons and positrons were supposed to travel in opposite directions round the giant circuit, but neither beam made it. CERN's investigators soon homed in on the section of the ring causing the trouble. When they dismantled it, they found that the high-vacuum tube through which the beams travel had been blocked by two beer bottles.