The eighteen arbitrary parameters of the standard model in your everyday life

Contrary to popular conception, the purpose of particle physics is to understand the everyday world. The current theory of fundamental interactions among the quarks and leptons depends on eighteen parameters, which are a priori arbitrary. Were these parameters different, our world would be changed dramatically. By exploring the connection between these parameters and everyday phenomena we can better appreciate the challenges confronting contemporary particle physics. Until we can explain the origin of these parameters, we cannot say we truly understand why our everyday world is as it is. [S0034-6861(96)00203-6]