Strahlungs-Emission und -Absorption nach der Quantentheorie [Emission and Absorption of Radiation in Quantum Theory]
FIRST PRINTING, EXCEEDINGLY SCARCE OFFPRINT, OF ONE OF EINSTEIN’S MAJOR WORKS: HIS DERIVATION OF PLANCK’S LAW AND THE FIRST PAPER ON THE THEORETICAL BASIS OF THE LASER. HIS SON, HANS ALBERT EINSTEIN’S COPY.
"Einstein commended the 'unparalleled boldness' of Planck's derivation of 1900, meaning not only the problem itself but also the fact that it was based on assumptions that were not entirely free of contradictions. Einstein now succeeded in the first of two papers in eliminating that flaw. More interesting than the derivation itself was the general character of his methods. Einstein proceeded from Niels Bohr's basic--and by then well tested--assumption that the electrons within an atom occupy a number of discrete energy states, and are able, through emission or absorption of radiation, to pass from one of those states to another. Added to this was an assumption of thermodynamic equilibrium between radiation field and atom, as well as a consideration of the 'classical' limiting case at high temperatures--and there was Planck's formula. This brief argument... also covers emission stimulated by the radiation field; thus the formulas already, by implication, contain the theory of the laser, though it was to take nearly half a century to be realized" (Folsing, Albert Einstein, 389). Weil *85.
The “implication” containing the theory of the laser was more fully developed in his companion paper “On the Quantum Theory of Radiation” published a few weeks later. In the first paper, Einstein wrestled with the concept that the atomic emission of radiation could be a directed process; in the second paper he convincingly demonstrates that this is indeed the case.
Provenance: From the collection of Einstein’s son, Hans Albert, with his stamp on the front wrapper.
OFFPRINT FROM: Verhandl. D. Deutch. Phys. Ges., Vol 18, pp. 318-323. Braunschweig: Druck und Verlag von Friedr. Vieweg and Son, 1916. Octavo, original wrappers. A fine copy.