Since the big discovery of 2012, the Large Hadron Collider at CERN has been accumulating data and making steady progress. Two recent results establish the origins of the mass of the two heaviest quarks
Every atom has a nucleus at its centre, and the smallest constituents of that nucleus are quarks. Named by Murray Gell-Mann after James Joyce’s Finnegan’s Wake, nothing is smaller than a quark. In fact as far as we know, quarks are infinitely small.
The idea of an infinitely small particle is difficult enough to grasp. It becomes even more so when we take into account that quarks have mass. Some of them have a lot of mass. The top quark (which, admittedly is not found very often inside a nucleus) has nearly as much mass as an atom of tungsten. On the tiny scales of particle physics, a tungsten atom is an enormous, sprawling thing. The bottom quark has a bit more mass than a helium atom, still pretty substantial by these standards.