Unified theory of elementary‐particle forces Available to Purchase

The notion of what are the “elementary” or structureless constituents of matter keeps changing as we are able to probe smaller and smaller distances with higher and higher energies. As long as we were limited by the energy available in chemical processes, the elementary particles were atoms; later they were protons, neutrons and electrons; currently we can smash matter into pieces sufficiently fine that quarks and leptons appear to be the elementary consituents of matter.