The Dirac spinors provide a complete and orthogonal set of solutions to the Dirac equation. This is most easily demonstrated by writing the spinors in the rest frame, where this becomes obvious, and then boosting to an arbitrary Lorentz coordinate frame. In the rest frame, where the three-momentum vanishes: p → → = 0 → → , one may define four spinors u ( 1 ) ( 0 → → ) = [ 1 0 0 0 ] u ( 2 ) ( 0 → → ) = [ 0 1 0 0 ] v ( 1 ) ( 0 → → ) = [ 0 0 1 0 ] v ( 2 ) ( 0 → → ) = [ 0 0 0 1 ]