“In his obituary for Stern {{w|Isidor Rabi|Rabi}} 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 {{w|Charles Enz|Charly Enz}} and Armin Telling – Pauli’s last two assistants – I have learned that Pauli has also discussed the question of {{w|Zero-point energy|zero point energies}} extensively with Stern during his Hamburg time, before the advent of the new quantum mechanics.”