Otto Stern

"A simple calculation shows that from the classical theory follows that we should find a broadening of the beam with the maximum intensity on the place of the beam without field. However, from the quantum theory follows that we should find there no intensity at all, and deflected molecules on both sides. The beam should split up in two beams corresponding to the two orientations of the magnet. The experiment decided in favor of the quantum theory."

"In his obituary for Stern wrote: “Some of Pauli’s great theoretical contributions came from Stern’s suggestions, or rather questions; for example, the theory of magnetism of free electrons in metals.” From and Armin Telling – Pauli’s last two assistants – I have learned that Pauli has also discussed the question of extensively with Stern during his Hamburg time, before the advent of the new quantum mechanics."

""Shall we do it?" "Well, then let's go, we shall do it!" Otto Stern asking, Walther Gerlach answering."