14.2. What is the Nature of Spin?
The best way to characterize spin is as a form of angular momentum. It is,
however, not the angular momentum associated with the operator L, as the following experiment shows. An electron is prepared in a state of zero linear momentum, i.e., in a state with a constant (space-independent) wave function. As the operators Lx, Ly , and Lz will give zero when acting on it, our existing formalism predicts that if the angular momentum along, say the z direction, is measured, a result of zero will obtain. The actual experiment, however, shows that this is wrong, that the result is 1h/24 It follows that the electron has "intrinsic" angular momentum, not associated with its orbital motion. This angular momentum is called spin, for it was imagined in the early days that if the electron has angular momentum without moving through space, then it must be spinning like a top. We adopt this nomenclature, but not the mechanical model that goes with it, for a consistent mechanical model doesn't exist. sayfa 373, Principles of Quantum Mechanics, Shankar. Benzer bir açıklama büyük bir ihtimalle Gasiorowicz in kitabında da vardır.