A search for the classical model of spin

The study of the motion of the magnetic top--a classical spherical top which carries magnetic moment proportional to its angular momentum--is motivated and inspired by the quantum mechanical relation between spin angular momentum and spin magnetic moment. Inversely, the magnetic top, taken to be the classical model of quantum spin, implies the description of spin states by probability amplitudes of the top orientation angles, instead of by Pauli spinors. This opens new possibilities for the interpretation of many interesting spin experiments which serve as tests of basic principles of quantum mechanics and of the postulates of the quantum theory of measurement. In the present paper, the authors describe some results of the research on the origin of spin, which lead to the theory of the quantum magnetic top. Quantization of the magnetic top leads to the Hamilton operator with eigenvalues equivalent to the eigenvalues of the Pauli operator. Open problems related to the magnetic to are also discussed. 32 refs., 1 fig.