Pauli letter collection: letter to Gunnar Källén

Pauli replies to Källén's letter of the 13 December 1957. Pauli agrees with him that the indefinite metric is the correct way. He talks about the macroscopic space-time description with complex roots and the Bisection of zero-states in parts corresponding to the upper and lower half-plane which must be connected with the difference between observed object and observing subject. By this bisection symmetric violations are introduced in a most natural way. He writes on his discussion with Heisenberg and on complex ghosts in weak interactions.