D O C U M E N T 1 8 3 J A N U A R Y 1 9 2 6 1 9 9 either one or the other direction or alternately in both directions during its absorp- tion, under the simultaneous influence of two contradirectional waves. And in considering whether impulses in such a case upset the statistical impulse equilibrium, one would first have to know roughly, when substituting the relation by general reciprocity statements, how these momentum considerations ought to be modified. This problem is attached to the question of the repulsion of one-sidedly emitting particles, to the extent that the possibility must be considered that the previously mentioned reflecting components of the one-sided emitting structure are not them- selves firmly coupled with the center of mass motion of the emitting atoms. Be- cause then such a radical change to the balance of momentum would perhaps be necessary. I write all this to you not without hesitation, but do not know any better alterna- tive. Surely you can relay to me something encouraging or cautionary from your own considerations, for which, in either case, I would be very grateful. With kind regards, yours sincerely, Walter Schottky 183. From Mileva Einstein-Mariü [Zurich, before 28 January 1926][1] Dear Albert, It’s been an eternity since I’ve written you. Meanwhile, we are already well into a new year for which I wish you all possible joyful wishes! I have in fact in the meantime heard a little about you. Mrs. Dolly R.[2] writes to me very enthusiastically about you however, she is also exceptionally nice, only she very much regretted not having “functioned” at all on that day she was tired and the social situation was too strange for her, so you must believe she is a lot nicer otherwise, when she is actually “functioning,” as she puts it. So far, things have gone well with the money so far, the matter has been [---], I don’t know when this settlement will happen the beginning of February is still possible.[3] In that case, I would still have to borrow some more here. It would be nice if you would write a few words in your next letter to the effect that you have nothing against it, so I am not somehow suspected of blowing the available money and then borrowing behind your back since that is not at all the case. Would you be so kind! hν c ----- - b a ⁄