A unified theory of elementary particles and forces
Scientific American, (April 1981)Abstract
The nature and development of a theory for the unification of all
elementary particles and forces, with the exception of gravity, are
discussed. The individual theories of leptons, quarks, electromagnetism,
the strong force and the weak force, which are seen as embedded in the
unified theory, are reviewed, and relations evident between the weak
force and electromagnetism are pointed out. The formulation of the
combined theory of the weak and electromagnetic forces by spontaneous
symmetry breaking with a critical distance of 10 to the -16th cm is
considered. A proposed unified theory for the three forces based on
SU(5) symmetry is outlined, and consequences of the theory for charge
quantization, lepton-quark interconversion, and the strengths of the
three forces at scales of less than 10 to the -29th cm are pointed out.
Possible experimental means of verifying the SU(5) unification are
considered, including the observation of baryon number nonconservation
in the decay of a proton and the predominance of matter in the universe.