Spin (physics) Spin (physics) In quantum mechanics and particle physics, spin is an intrinsic form of angular momentum carried by elementary particles, composite particles (hadrons), and atomic nuclei. Spin is one of two types of angular momentum in quantum mechanics, the other being "orbital angular momentum". The orbital angular momentum operator is the quantum-mechanical counterpart to the classical angular momentum of orbital revolution and appears when there is periodic structure to its wavefunction as the angle varies. The existence of spin angular momentum is inferred from experiments, such as the Stern–Gerlach experiment, in which silver atoms were observed to possess two possible
Ugo Fano Fano spent 1936–37 with Werner Heisenberg in Leipzig. In 1939, he married Camilla Lattes, also known as "Lilla", a teacher who would collaborate with him in a well-known book on atomic and molecular physics, "Physics of Atoms and Molecules" (1959). Appendix III of this book presents an elementary description of the collision of two charged particles, which was used by Richard Feynman in lectures that have been published as "". An expanded version of this book was subsequently published as "Basic Physics of Atoms and Molecules" (1972). Later that year, he immigrated to the United States due to increasing antisemitic