1 4 6 D O C U M E N T 1 3 6 J A N U A R Y 1 9 2 8 Harry Keßler, Prof. Albert Einstein, Toni Pfülf, M. d. R., Simon-Franken M. d. R., Roßmann M. d. R., German Peace Society, German Metal Workers Union, German Monistic Association, Railwaymen’s Union, Women’s League for Peace and Free- dom, Union of German Miners. 136. To Otto Stern [???, before 21 January 1928][1] Dear Mr. Stern, In thinking over our quantum seminar, two questions have arisen that deal with the behavior of a molecular beam in a magnetic field thus they concern precisely your area of interest. Perhaps you have already carried out the corresponding ex- periments if not, then these suggestions may prove useful. I. Anmolecule atom can orient itself relative to a vertical magnet either ↑ or ↓. The direction of the magnetic field is slowly changed. Does each individual atom then follow the field in its orientation? Test: [2] Captions: atomic beam magnetic edges The atomic beam passes through two oppositely directed, inhomogeneous mag- netic fields, one after another. Let an atom be oriented such that it is deflected up- wards by the first field. If it reorients in the second field, then owing to the reversal of the field[3] and the reversal of the dipole, the same deflection would be observed as if the two fields had been parallel. This is all the more paradoxical since the de- flection effect increases linearly with increasing field strength. II. It is a characteristic of our current state of understanding that the field deter- mines the orientation of the molecule atom, while the field gradient determines the magnitude of its deflection. Field and field gradient can be varied quite inde- pendently from one another. Let us suppose that the field gradient is fixed and the field is varied then only the direction of the latter, but not its strength, is the deter- mining factor. The field strength can thus be made arbitrarily small without having [2]