Scientists say they will need at least four months to reopen the world’s biggest particle physics laboratory after the coronavirus crisis forced CERN to move nearly all 8,000 staff off-site. While that’s already a huge undertaking, it pales in comparison with the colossal task of restarting CERN’s gigantic complex of particle accelerators, which includes the atom-smashing Large Hadron Collider. Frédérick Bordry, director for Accelerators and Technology and part of CERN’s crisis team, explains the work behind this complex process.