THE GOD PARTICLE

While walking in the Scottish Highlands in 1964, physicist Peter Higgs thought of a way to give particles their mass. He called this his 'one big idea'. Particles seem more massive because they are slowed while swimming through a force field, now known as the Higgs field. It is carried by the Higgs boson, referred to as the 'God particle' by Nobel laureate Leon Lederman.

Why does anything have a mass? A truck is heavy because it contains a lot of atoms each of which might itself be relatively heavy. Steel contains iron atoms and they fall far down the periodic tablel. But why is an atoms heavy? It is mostly empty space after all. Why is a proton heavier than an electron, or a neutrino, or a photon?

Although the four fundamental forces, or interactions, were well known in the 1960, they all relied on quite different mediating particles. Photons carry information in electromagnetic interaction, gluons link quarks by the strong nuclear force and the W and Z bosons carry weak nuclear forces. But photons have no mass, whereas the W and Z bosons are very massive particles, a hundred times as massive as the proton. Why are they so different? This discrepancy was particularly acute given that the theories of electromagnetic and weak forces could be combined, into an electroweak force. But this theory did not predict that the weak nuclear force particles, the W and Z bosons, should have a mass. They should be just like the massless photon. Any further combination of fundamental forces, as attempted by the grand unified theory, also ran into the same problem. Force carries should not have any mass. Why weren't they all like the photon?