ABSTRACT
How does this formula transform for relativistic energies? 1.11. For second-order matrices, the matrices σµ and the unit matrix constitute a basis. Let us confront every real four-vector xµ with the Hermitian matrix Y according to the following rule:
Y = xµσµ =
( x0 + x3 x1 − ix2 x1 + ix2 x0 − x3
) .
