"Designed to recreate the conditions just after the Big Bang, the Large Hadron Collider, 27 kilometers (16.7 miles) long, is housed in a pipe-like structure 100 meters below ground. As part of the experiment, two beams of subatomic particles, called 'hadrons,' travel in opposite directions inside the circular accelerator, gaining energy with every lap. Physicists then let them collide head-on into each other and measure the results with the CMS and other instruments."