Bohr's atomic model revisited

EPR before EPR: a 1930 Einstein-Bohr thought experiment revisited

In 1930 Einstein argued against consistency of the time-energy uncertainty relation by discussing a thought experiment involving a measurement of mass of the box which emitted a photon. Bohr seemingly triumphed over Einstein by arguing that the Einstein's own general theory of relativity saves the consistency of quantum mechanics. We revisit this thought experiment from a modern point of view at a level suitable for undergraduate readership and find that neither Einstein nor Bohr was right. Instead, this thought experiment should be thought of as an early example of a system demonstrating nonl…

从现代视角重新审视玻尔和索默费尔德的旧量子力学

Old Quantum Mechanics by Bohr and Sommerfeld from a Modern Perspective

本文从现代视角重新审视旧量子力学，通过半经典方法推导量子化规则和能级，并探讨经典到量子理论的过渡。

The many faces of the Bohr atom

The atomic model that Niels Bohr suggested in 1913 celebrated its greatest victories in connection with one-electron atoms. Among them were the isotopic spectral effect and what became known as Rydberg atoms, insights that were fully recognized only many years later. He considered the original ring model a first step towards an understanding of atomic structure, and during the following years he developed it into more ambitious models that, he hoped, would also describe many-electron atoms. His theory of the periodic system marked the culmination of the orbital atom within the framework of the…

Spreading the gospel: The Bohr atom popularised

The emergence of quantum theory in the early decades of the twentieth century was accompanied by a wide range of popular science books, all of which presented in words and in images new scientific ideas about the structure of the atom. The work of physicists such as Ernest Rutherford and Niels Bohr, among others, was pivotal to the so-called planetary model of the atom, which, still today, is used in popular accounts and in science textbooks. In an attempt to add to our knowledge about the popular trajectory of the new atomic physics, this paper examines one book in particular, coauthored by D…

The Kantian Framework of Complementarity

A growing number of commentators have, in recent years, noted the important affinities in the views of Immanuel Kant and Niels Bohr. While these commentators are correct, the picture they present of the connections between Bohr and Kant is painted in broad strokes; it is open to the criticism that these affinities are merely superficial. In this essay, I provide a closer, structural, analysis of both Bohr's and Kant's views that makes these connections more explicit. In particular, I demonstrate the similarities between Bohr's argument, on the one hand, that neither the wave nor the particle d…

Early Atomic Models - From Mechanical to Quantum (1904-1913)

A complete history of early atomic models would fill volumes, but a reasonably coherent tale of the path from mechanical atoms to the quantum can be told by focusing on the relevant work of three great contributors to atomic physics, in the critically important years between 1904 and 1913: J. J. Thomson, Ernest Rutherford and Niels Bohr. We first examine the origins of Thomson's mechanical atomic models, from his ethereal vortex atoms in the early 1880's, to the myriad "corpuscular" atoms he proposed following the discovery of the electron in 1897. Beyond predictions for the periodicity of the…