Last week it was announced that the particle beams had fully circulated around the LHC for the first time in over a year.  The accelerator had been offline until this August due to damage.  A bad electrical connection had caused extensive damage and forced a shutdown last Fall, and intensive repair process was delayed by the winter.

With repairs at last complete, and beams circulated, this week researchers decided to bump the testing up to collisions. 

To gain a proper perspective on these collisions, it's first important to understand how they work.  Housed 100 meters under the Franco-Swiss border, the LHC sends proton beams hurtling in opposite directions down a 17-mile-long track at close to the speed of light.  The beams are bent in the proper direction by over 1,200 massive superconducting magnets. The beams cross at allotted spots, and the protons contain within collide.  The results are captured by four advanced detectors bordering the crossing points -- ATLAS, the Compact Muon Solenoid (CMS), Alice and LHCb.  Atlas and CMS are general purpose detectors, while the remaining two are special purpose detectors.

On Monday, coinciding with a CERN press conference, at 1322 GMT the Atlas detector became the accelerator's first to record a collision.  The Alice and LHCb recorded collisions at 1600 GMT.  And with a bit of tweaking collisions were recorded by the Compact Muon Solenoid detector at 1800 GMT. 
Fabiola Gianotti, spokesperson for the Atlas scientific team comments, "This is great news, the start of a fantastic era of physics and hopefully discoveries after 20 years' work by the international community."

CERN's director-general Rolf Heuer comments, "It's a great achievement to have come this far in so short a time.  But we need to keep a sense of perspective - there's still much to do before we can start the LHC physics programme."

The collider already offers an extreme environment, with particles moving at close to the speed of light and temperatures of 1.9 degrees Kelvin.  While some might wonder why those temperatures are necessary, they're designed to simulate conditions at the time of the Big Bang, the cosmological event that created the universe as we know it. 

However, in order to get closer to these conditions, the energy of the beams will need to be bumped up from low-to-moderate power to 7 TeV (14 TeV combined).  A flying mosquito has approximately 1 TeV of kinetic energy.  While "14 mosquitos" worth of combined energy may not seem like much, its a massive achievement for man to pack that much energy into a pair of protons.