The Large Hadron Collider (LHC) is back in action today, firing proton beams around its 27-kilometer track. The LHC has been out of active commission for two years for upgrades, maintenance, and consolidation. The most recent delay was due to a short-circuit. Its repairs didn't take as long as originally anticipated, but were tedious because the parts in need of repair operate at temperatures near absolute zero. So, the device had to be slowly thawed and then painstakingly re-frozen before it could begin operation again.