I have added a section on the Axiom of Choice to The Relativistic Unit Circle.
Axiom of Choice
This shows the relation of the positive and negative axes in two dimensions as the foundation of the Pauli/Dirac matrices, and their relation to the null vector....
Edit:I just added the final comment to the pdf document:
The Null Vector
If the axes represent converging forces at the origin, then the null vector represents equal and opposing forces as the interaction” cross product.
That is, for