3 8 D O C U M E N T 1 5 J U N E 1 9 2 7 Just recently, I looked over your Kaluza papers,[5] unfortunately in somewhat of a hurry, since I can only spend an hour or part of an hour at a time in the library.— “In the preferred coordinate system” means, if I remember correctly, that one co- ordinate corresponds to the potential. Now, all the potential differences that occur are small relative to those between the proton (outer surface or a corresponding lo- cus) and the electron, and thus the singularities quite near to two hypersurfaces— so that the quanta are for the most part in the neighborhood of a third hypersurface that lies in between, and that includes all the potentials that are not in the immediate neighborhood of the protons and electrons. Is that essentially correct? Are these three regions of high occurrence not apparently determined by quantum theory?— And: what is in fact Sommerfeld’s generalized p, q space? —If I hadn’t just had another reason to write to you, I would have first attempted to think out the problem on my own: But as it is, don’t hold it against me.— I am apparently simply lazy—the most clear-cut part of my daily labors is that I perform a Paradiso commentary service for Dr. Sautter during our joint walk home.[6] Warm regards, from Anna[7] also, your Michele 15. To Michele Besso [Berlin,] 29 June 1927 Dear Michele, I will try to fulfill Mr. Bandi’s wish if possible.[1] But I don’t know whether I can get the aviators to take the thing. I would also like to sell a manuscript to a crazy admirer in order to use the proceeds to give Marie something for the education of her children.[2] I am coming to Switzerland in July and hope to visit you there. In the meantime, warm regards to you and Anna—[3] Your Albert