Classical analog of spin in 7 and in 10 dimensions
  Extra dimensions are introduced: 3 in Classical Mechanics and 6 in Relativistic Mechanics, which represent orientations, resulting from rotations, of a particle, described by quaternions, and leading to a 7-dimensional, respectively 10-dimensional, world. The concept of spin is thus defined in both cases, which results to be different from angular momentum. It leads to the known concept of Quantum Mechanical spin in both cases. In particular, application of these new ideas to (Relativistic) Quantum Mechanics, leads to quantization of energy levels in free electrons, which could be in principle detectable via their spectrum, confirming the theory. 
Evangelos Chaliasos