This book reexamines the birth of quantum mechanics, in particular examining the development of crucial and original insights of Bohr. In particular, it gives a detailed study of the development and the interpretation given to Bohr's Principle of Correspondence. It also describes the role that this principle played in guiding Bohr's research over the critical period from 1920 to 1927.

This article argues that a manuscript dated to the summer of 1927 by the editors of Bohr’s Collected Works was written a year earlier. The re-dating allows the conclusion that Bohr was well on his way to complementarity before his famous fight with Heisenberg over the uncertainty principle early in 1927. The literature that assumes that complementarity was Bohr’s response to Heisenberg is therefore in error. The editors of the Collected Works assigned the document the date of 1927 because it (...) refers to electron-diffraction experiments by Davisson and Germer, which were published in 1927. But as the article points out, Bohr and other leading physicists such as Max Born met Davisson in Britain in 1926 and discussed the experiments with him then. That demolished the basis of the earlier dating. Finally, the article argues that when the document takes its place between the Bohr–Kramers–Slater theory (1924) and the 1927 drafts of complementarity, everything falls neatly into place. (shrink)

This article examines the problem of the origins of the correspondence principle formulated by Bohr in 1920 and intends to test the correctness of the argument that the essential elements of that principle were already present in the 1913 “trilogy”. In contrast to this point of view, moreover widely shared in the literature, this article argues that it is possible to find a connection between the formulation of the correspondence principle and the assessment that led Bohr to abandon the search (...) for a Planck-type theory. In fact, a thorough examination of Bohr’s works shows that the birth of this principle coincided with the depletion of a research program whose origins may date back to Bohr’s stay at the Rutherford’s laboratory (summer 1912). Finally, this article argues that original program of research was abandoned when it became clear that Planck’s quantum hypothesis for the harmonic oscillator was not an adequate support for the theoretical architecture of atomic physics; namely, there was evidence enough to justify a most drastic conclusion, according to Bohr: “I do not think that a theory of the Planck type can be made logical consistent”. (shrink)