Nuclear Physics

Nuclear physics studies the structure and behavior of atomic nuclei — the tiny, incredibly dense core of atoms comprising protons (positive charge) and neutrons (no charge), held together by the strong nuclear force (the most powerful fundamental force in nature, acting only at sub-femtometer distances). The proton and neutron themselves are made of quarks, bound by gluons. Key phenomena: radioactive decay (nuclei spontaneously emit alpha particles, beta particles, or gamma rays as they transform to more stable configurations); nuclear fission (heavy nuclei splitting, releasing energy — the basis of nuclear power and bombs); nuclear fusion (light nuclei merging, releasing far more energy — the source of stellar energy and the basis of hydrogen bombs). Ernest Rutherford's gold foil experiment (1909) discovered the atomic nucleus; Marie Curie's research defined radioactivity.