Yet another formulation of the Dirac equation

Abstract

The 2-by-2 Pauli matrix algebra is used to write the 1-by-4 Dirac field ψ in anequivalent 2-by-2 matrix η. The current 4-vectors$\bar \psi \gamma _\mu \psi$ and η*σ_µη are then compared and the latter is shown to not be easily interpretable as a probability density, and also tocontain $\bar \psi \gamma _\mu \psi$.