Pauli letter collection: letter to Josef Maria Jauch

Pauli writes about his renouncing the partnership with Heisenberg. He thinks there are mistakes in Heisenberg's integration of his equation. Futher, if one attempts to loosen either the causality or the unitarity of the metric, this leads to disastrous results in relativistic theories. His impression is that one has to wait for new physical ideas, because mathematical virtuosity alone cannot lead to the discovery of new laws of nature.