ABSTRACT
This chapter concerns possible unifications between the four fundamental interactions. First, comparisons between strong interactions (as described by quantum chromodynamics), weak interactions, electromagnetic interactions (as described by quantum electrodynamics), and gravitational interactions (as described by Newton’s law of gravity and by Einstein’s general theory of relativity) are discussed, in relation to their quanta, range, theories, participants, and strengths. Electroweak unification is shown to imply the existence of the Higgs boson, which has been experimentally detected in recent years at CERN. Grand unification is shown to imply the existence of X bosons and Y bosons which allow quarks to change into leptons, and matter to change into antimatter, and vice versa. Superunification, or a theory of everything, may involve strings and branes in up to 11 dimensions in a construct known as M-theory. The energy scale for this is the Planck energy.
