Heisenberg replies to Pauli's letter, which convinced him that the infinity of the energy values is unavoidable, and that this is connected with shower production. Probably the whole quantum theory of wave fields is wrong. Neumann's suggestion is a possible way out of the dilemma.
Heisenberg, WernerHeisenberg thinks that his description of the lowest state (vacuum) is correct, but he does not yet understand how particles as higher states result from his mathematics.
Heisenberg, WernerHeisenberg comments on the latest results on showers and talks about possible reasons for the high penetrability of cosmic radiation and calculations on wave-quantization. He writes against the cut-off-method and gives an introduction to the universal length in a new operator. The question remains whether this can lead to a relativistic and convergent theory.
Heisenberg, WernerBhabha's and Heitler's assumptions confirm Heisenberg's idea of the necessity for introducing a universal length. He writes about difficulties in the interpretation of cosmic radiation experiments with the Yukawa theory.
Heisenberg, WernerHeisenberg thinks, after receipt of Yukawa's paper, that his Hamiltonian is better than that of Kemmer or Bhabha. He writes on the Beta-instability of the yukon. He sends Pauli a short paper on the limitations of quantum mechanics and asks for his comments.
Heisenberg, WernerHeisenberg writes on the impossibility of measuring the power law exp (-k.r)/r at large distances and about Stark's article in "Nature".
Heisenberg, WernerHeisenberg replies to objections from Pauli regarding his work on quantum electrodynamics, in particular in connection with the S-matrix.
Heisenberg, WernerHeisenberg talks about the arguments of his collaborators against his axiomatics.
Heisenberg, WernerHeisenberg asks about the formulation of the difference between $\Psi$* and $\Psi$+ in the Dirac theory, with reference to the operator $\eta$.
Heisenberg, WernerHeisenberg agrees with Pauli that one cannot make the S-matrix alone a starting point of a quantized field theory. There is discussion of other possible presuppositions.
Heisenberg, Werner