1 1 8 D O C U M E N T 9 9 N O V E M B E R 1 9 2 5 Prof. Born and I have attempted to develop in a paper into a systematic theory (ini- tially for one degree of freedom).[3] (If I am not mistaken, a correction proof of this paper has been forwarded to you.) The enclosed notes are intended for a paper by Born, Heisenberg, and me,[4] in which the theory of quantum mechanics is generalized to several degrees of free- dom and is expanded in various points. They contain a) a remark about the statistics of quantized eigen-oscillations. When this is done reasonably (Debye’s statistics is unreasonable[5] ), one automatically arrives at Bose’s statistics, except that it is called “eigen-oscillation” instead of a “cell.” But this is actually quite trivial. The pertinent expositions are probably going to have to be shortened somewhat as well, because, as we found out subsequently, Planck already said similar things in his most recent paper [6] b) a computation of energy fluctuations like interference, taking quantum me- chanics as a basis for the eigen-oscillations. This computation happily leads to the correct result[7] . Unfortunately the calculation will be ¢rather² hard to understand without the preceding paragraphs of the paper. But it is certainly correct. Our paper should be complete in 8 to 14 days. (Prof. Born departed yester- day for America.) A copy of the correction proofs is supposed to be forwarded to him. With kind regards, I am respectfully and sincerely yours, Pascual Jordan 99. To Mileva Einstein-Mariü [Berlin,] 1 November [1925][1] Dear Mileva, I already wrote an urgent letter to Anschütz.[2] Hopefully, it will help. There are still Gonzenbach, Zangger, and Zürcher.[3] You’ve already spoken to Gonzenbach, so I think it’s better if I only write to him if your effort with him hasn’t entirely had the desired success. One shouldn’t play all the cards right from the beginning. I’ll write to Zangger, but I don’t think he can have much influence on Albert,[4] since he is so distracted. Zürcher can achieve more. I won’t write him right away but will keep him in reserve. If, in fact, too much happens all at once, it will seem too col- lusive and, for that reason, won’t work. Concerning the declarations to be made, Albert and Tete should state (for the lat- ter, you would have to draw up the declaration with the approval of the guardian- ship authorities):[5] Δ2 E E2 const.V ----------------- -+=