I think to get some sort of understanding (instead of just operative understanding of quantum mechanics) you have to dive relatively deep into theoretical physi

I think to get some sort of understanding (instead of just operative understanding of quantum mechanics) you have to dive relatively deep into theoretical physics. Spin can then arise from enhancing the Schrödinger equation with a relativistic description of mass and impulse [0]. [0] https://en.wikipedia.org/wiki/Dirac_equation https://en.wikipedia.org/wiki/Dirac_equation