Pauli letter collection: letter to Wolfgang Pauli

Heisenberg does not think that substraction physics makes sense. He writes about what he has learned of nuclear physics in Copenhagen, about the order of magnitude of exchange forces, and Bethe's suggestion to replace Fermi's relation for interaction by another. He writes about the explanation of all mass defects by a plausible exchange force and he belives that the theory of the positron and quantum electrodynamics should be brought in order before attacking nuclear problems.