# 4 CERN hadron collider fires up again to reveal cosmic secrets
The world’s largest and most powerful particle accelerator is up and running again in Switzerland after a three-year refurbishment. And it is off to a record-breaking start as scientists try to unlock the secrets surrounding the building blocks of the universe. Physicists hope it will reveal the secrets of “dark matter” that makes up 85 percent of our universe, but does not absorb, reflect or emit light.
