Magic Numbers in Exotic Nuclei and Spin-Isospin Properties of the $\mathit{NN}$ Interaction

The magic numbers in exotic nuclei are discussed, and their novel origin is shown to be the spin-isospin dependent part of the nucleon-nucleon interaction in nuclei. The importance and robustness of this mechanism is shown in terms of meson exchange, G-matrix, and QCD theories. In neutron-rich exotic nuclei, magic numbers such as $N=8\mathrm{}$, 20, etc. can disappear, while $N=6\mathrm{}$, 16, etc. arise, affecting the structure of the lightest exotic nuclei to nucleosynthesis of heavy elements.