The Hoyle State

Nuclear physics is complicated compared to atomic physics, because the strong force is complicated compared to the electromagnetic force, and nucleons—protons and neutrons—are bag-like groupings of quarks and gluons held together by the strong force, elastic bags which attract each other and jostle each other closely in the nucleus… all governed by the rules of quantum mechanics.

To begin to understand such a complex thing as a nucleus, people started with approximate models. In 1930 George Gam...