Five fundamental forces exist in nature. The "electric" force is applied directly between electric charges. The "magnetic" force pushes charges sideways. The "strong" force holds an atom's nucleus together. The "weak" force is responsible for radioactive decay; and, "gravity" binds clusters of matter together. The term "grand unified theory" applies to any theory which connects the electric, magnetic, strong, and weak forces. Until this year, only the electric, magnetic, and weak forces had been connected. That changed when H. A. Shick's book Field Particle Physics... was published. In his book, Shick explains how the nucleus is physically held together by the electric force. This explanation completes the grand unified theory in every way but one. It is not theoretical.
"FIELD PARTICLE PHYSICS..." Blog
Advancing Physics Beyond Theory