We've been waiting decades for this and here it is - first collisions at the LHC! WooHoo! The ATLAS detector saw the first collision this afternoon, followed soon by CMS. The machine was then tuned to give the LHCb and ALICE detectors collisions this evening, so all 4 experiments have had a taste of the fruit. The machine energy is set to the injection energy, 450 GeV per beam, which is a very safe way to start. They expect to ramp up to 1.2 TeV per beam to achieve the world's highest energy collisions just before Christmas. Here is the event display for the first collision in CMS:
Looks like 2 hard jets. A running commentary of the day's events at CMS can be found here. Let the science begin!