The believe-it-or-not superlatives are so extreme and Tom Swiftian they make you smile. The L.H.C. is not merely the world’s largest particle accelerator but the largest machine ever built. At the center of just one of the four main experimental stations installed around its circumference, and not even the biggest of the four, is a magnet that generates a magnetic field 100,000 times as strong as Earth’s. And because the super-conducting, super-colliding guts of the collider must be cooled by 120 tons of liquid helium, inside the machine it’s one degree colder than outer space, thus making the L.H.C. the coldest place in the universe.