(I wrote this about four years ago. I think it’s still relevant) What do they do at CERN? It’s simple — they smash things, ions for example, together at high speed. Why do they do that? It’s even more simple — to see what happens! CERN is an example of “blue skies” research: particles are not smashed together to solve any practical problem but to test theories of matter and energy. We’re paying for it — and we should be! Physicists have been smashing particles for quite a long time, over 50 years at CERN and about 100 years altogether. It first revealed the structure of atoms. In 1911, Rutherford’s team bombarded gold atoms with fast-moving alpha particles. Their behaviour showed that atoms are almost entirely empty space populated by some electrons, with an incredibly dense nucleus (1 cubic millimetre of nuclei would weigh about 200000 tonnes). This “blue skies” research gave rise to modern atomic theory and the nuclear age. More recently, particle accelerators proved a theory about the forces of nature. In 1983, particles predicted by the proposed unification of the electromagnetic and weak forces, vector bosons, were produced at CERN. This helped support the so-called Standard Model which seeks a unified description of three of the four forces of nature. What is the Large Hadron Collider (LHC)? The LHC is a colossal piece of apparatus designed to produce the predicted Higgs boson, a particle that gives mass to other particles. This would further confirm the Standard Model. It accelerates two beams of charged particles round a 27km tunnel beneath the Swiss-French border until they almost reach the speed of light (c), nearly 300,000km/s. They circulate some 10,000 times per second.