Beginning with the seminal work of Rutherford, Geiger and Marsden in 1911,
physicists have investigated the atom using particle beams (alpha particles,
and protons) as probes. They developed new detection methods; the geiger
counter, scintillators, cloud and then bubble chambers. This new paradigm
for probing matter and new detectors led to many discoveries.
To make a long story short, by 1974 the chaos of discovery lead to the
Standard Model describing all observed particle phenomena in terms of three
fundamental forces (4 including gravity) and the fundamental building blocks
of matter, quarks and leptons.
Only now, after the dust of this chaotic discovery settles, are we able with
hindsight to recognize the underlying principles which define the theory we
call the Standard Model. It is these principles and their logical extension
which I will attempt to describe in this talk.