The Quantum Theory of Emission and Absorption of Radiation. SS. 243-265. In: Proceedings of the Royal Society of London. Series A, Vol. 114.
(24,5 x 16,5 cm). SS. 137-366. Mit zahlreichen Abbildungen und Tafeln. Moderne Broschur.
(London, Harrison, 1927).
Erste Ausgabe dieser bedeutenden Arbeit zur Entwicklung der Quantentheorie. - "A New Radiation Theory... The first results of this strategy were almost miraculous. First came his new radiation theory, in February 1927, which quantized for the first time James Clerk Maxwell's radiation in interaction with atoms. Previous quantum-mechanical studies of radiation problems, except for Jordan's unpopular attempt, retained purely classical fields. In late 1925 Jordan had applied Heisenberg's rules of quantization to continuous free fields and obtained a light-quantum structure with the expected statistics (Bose Einstein) and dual fluctuation properties. Dirac further demonstrated that spontaneous emission and its characteristics - previously taken into account only by special postulates - followed from the interaction between atoms and the quantum field. Essential to this success was the fact that Dirac's transformation theory eliminated from the interpretation of the quantum formalism every reference to classical emitted radiation, contrary to Heisenberg's original point of view and also to Schrödinger's concept of Psi as a classical source of field. This work was done during Dirac's visit to Copenhagen in the winter of 1927. Presumably to please Bohr, who insisted on wave-particle duality and equality, Dirac opposed the 'corpuscular point of view' to the quantized electromagnetic 'wave point of view.' He started with a set of massless Bose particles described by symmetric Psi waves in configuration space. As he discovered by 'playing with the equations,' this description was equivalent to a quantized Schrödinger equation in the space of one particle; this 'second quantization' was already known to Jordan, who during 1927 extended it into the basic modern quantum field representation of matter. Dirac limited his use of second quantization electromagnetic to radiation: to establish that the corpuscular point of view, once brought into this form, was equivalent to the wave point of view" (DSB). - Erstes Blatt gestempelt, sonst sauber und gut erhalten. - DSB 17, 224