The quantum postulate and the recent development of atomic theory. - [COINING THE TERM 'COMPLEMENTARITY']

London, Macmillan and Co., 1928. Royal8vo. In recent full blue cloth with gilt lettering to spine. Extracted from "Nature", January - June, 1928, Vol. 121. Entire April 14-issue offered. Fine and clean. [Bohr:] Pp. 580-90. [Entire issue:] Pp. 561-608. First edition of Bohr's exceedingly influential statement of his 'complementarity' principle, the basis of what became known as the 'Copenhagen interpretation' of quantum mechanics. In the paper he coined the term 'complementarity' and thereby created an entire new fundamental principle of quantum mechanics."Immediately after Heisenberg's work on uncertainty relations, Bohr presented his concept of complementarity at a conference a Lake Como in Italy. Bohr's lecture marked the first attempt to provide a genuine philosophical underpinning to the new advances in physics. The uncertainty relations had provided Bohr a concrete measure of the consequences of the wave-particle duality and thereby a physics-based justification for the ideas he was working on. Bohr had already embraced the wave-particle duality underlying quantum theory and he presented the concept of complementarity as the fundamental feature of a new conceptual framework broad enough to include it" (Paul McEvoy, Niels Bohr). "For Bohr, complementarity was an almost religious belief that the paradoxes of the quantum world must be accepted as fundamental, not to be 'solved' or trivialized by attempts to find out 'what's really going on down there.' Bohr used the word in an unusual way: the 'complementarity' of waves and particles, for example (or of position and momentum), meant that when one existed fully, its complement did not exist at all" (Louisa Gilder, The Age of Entanglement). "The lecture was published in Nature in 1928 in a revised form It sparked significant debate in the years that followed and solidified the boundaries between those who accepted Bohr's view of the consequences of quantum theory and those who were seeking a more 'realistic' microscopic theory or a more realistic interpretation of quantum theory itself" (McEvoy, P. 70).The paper was published almost simultaneously in English, Danish, English, French and German, the present English publication being the first.