Es notable todo los temas en los que se involucró Jordan, estando cerca de Born:
For his dissertation under Born, Jordan worked on a problem in the theory of light quanta (Jordan 1925) that dealt with the interaction of electrons and radiation. In it he tried to disprove Einstein"s hypothesis that in the process of absorption or emission of a photon of energy hv by an atom an amount of momentum hi"/c is transferred by or to the photon. Einstein, in a brief note to the Zeitschrift für Physik, took exception with Jordan"s work. He pointed out that Jordan"s paper was based on a hypothesis that implied "that the amounts ol radiation taken (by an atom exposed to blackbody radiation) from rays of different directions were treated as not being independent of each other" and that this would result in consequences contrary to observation (Einstein 1925). After finishing his thesis in the fall of 1924, Jordan worked with James Franck on problems connected with spectroscopy. He helped him write volume 3 of the series Struktur der Materie which Bom and Franck edited. The book was published with Franck and Jordan as coauthors, with the title Anregung von Quantensprüngen der Stosse. During that same year Jordan wrote several papers dealing with problems in atomic structure and spectroscopy. He also collaborated with Born on a paper in the quantum theory of aperiodic processes. By generalizing Kramers and Heisenberg"s dispersion-theoretic approach, they calculated the effect on an atom of an electric field whose time dependence is arbitrary. The arbitrary time dependence was to allow them to simulate the effect of a charged projectile particle during an atomic collision.
Es interesante notar que se había familiarizado con las ideas y formalismo matemático de Kramers y Heisenberg sobre la dispersión de radiación por un átomo. Parte de ese formulismo será usado por Heisenberg en su gran "paper" de 1925.
Con este post termino la serie. Luego, la historia de Jordan ya cae en un periodo más allá de sus primeros años, donde comienza a aportar nuevas ideas a la mecánica cuántica y la teoría de campos.
Angel "Java" Lopez