The particle physics kaleidoscope

Particle physics in the past quarter century has developed a great deal and we see that what we considered before as accidents are essential parts of the design of the world. We see for example that the muon and its neutrino have their counterpart in the strange and charmed quarks just as the electron and its neutrino are the counterparts of the down and up quarks. A third pair of pairs is provided by the tau lepton and and its partner and the top and bottom quarks. This close similarity of quarks and leptons is an update of the baryon-lepton symmetry; and it has prompted Pati and Salam to consider leptons as quarks of a fourth color. Particle physics shows no signs of slowing down. Much of its renewed vigour has been due to accepting concepts and models from condensed matter physics. In other areas like the study of monopoles and other topological structures it is the insistence of fundamental quantum questions that give vigour. The author gives a history of particle physics from its birth in the early 1900s to today