In this essay we discuss epistemological implications of relativistic
quantum field theory. The empirical domain of such a theory is formed by
phenomena ascribed to subnuclear particles, sometimes still called
elementary particles. This latter more traditional design at ionrejects
the lasting desire of physicists to eventually second and isolate
irreducible constituents of matter. Going down to the atomic level,
electrons appear to play such a role, whereas the nuclei of atoms can be
considered as compound systems of protons and neutrons, i. e. of two
species of particles. This view makes sense, since the respective number
of these two types of constituents essentially identifies an atomic
nucleus. Extracted from a nucleus, however, the 'free' neutron is an
unstable particle: it decays spontaneously into a proton, an electron
and an anti-neutrino. In the past fifty years or so basically the
bombardment of matter by protons or by electrons in specially devised
experiments has revealed a large variety of further subnuclear objects.
Successive generations of accelerators and refined collision devices
provided higher and higher collision energies. All theses- nuclear
objects are termed 'particles' in the physics community, nearly all of
these objects are unstable and decay spontaneously into other ones. The
respective lifetimes of the distinct types, however, differ widely,
ranging from 3 - 25 relatively long(10 sec) to extremely short(10 sec).
Because of this huge disparity in lifetime the notion of a particle
deserves particular attention, a point laid stress on in our
consideration. The study of the physical behaviour of these subnuclear
particles led to distinguish three types of interactions: the strong,
the electromagnetic and the weak interaction. As the names suggest these
interactions differ in their respective strength.
