CERN, the physics laboratory near Geneva, Switzerland, is well known as the home of the world’s biggest particle smasher, the Large Hadron Collider (LHC). On Tuesday it revealed a design study for an even bigger machine, the Future Circular Collider (FCC).

Costs start at €9 billion for the least expensive version, going up to an eye-watering €21 billion for the grandest vision. Inside a 100-kilometre-long ring tunnel, particles would be smashed together at energies which dwarf those achievable in the LHC. The idea has created plenty of excitement. The problem is, it is …