The Philosophical Magazine A Journal of Theoretical Experimental and Applied Physics

Niels Bohr and the dawn of quantum theory

P. Weinberger

Published Aug 28, 2014• 15 citations

Abstract

Bohr’s atomic model, one of the very few pieces of physics known to the general public, turned a hundred in 2013: a very good reason to revisit Bohr’s original publications in the Philosophical Magazine, in which he introduced this model. It is indeed rewarding to (re-)discover what ideas and concepts stood behind it, to see not only ‘orbits’, but also ‘rings’ and ‘flat ellipses’ as electron trajectories at work, and, in particular, to admire Bohr’s strong belief in the importance of Planck’s law.

DOI: 10.1080/14786435.2014.951710

Related papers

Atoms, Metaphors and Paradoxes

Sandro Petruccioli

This book gives a detailed study of the development and the interpretation given to Niels 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. Quantum mechanics, developed in the 1920s and 1930s by Bohr, Heisenberg, Born, Schrödinger and Dirac, represents one of the most profound turning points in science. This theory required a wholly new kind of physics in which many of the principles, concepts and models representing reality, that had formed the basis of classical physics since Galileo and Newton, had to be abandoned. This book re-examines the birth of quantum mechanics, in particular examining the development of crucial and original insights of Niels Bohr.

Cambridge University Press eBooksNov 18, 199340 citations

Niels Bohr’s First 1913 Paper: Still Relevant, Still Exciting, Still Puzzling

Kenneth W. Ford

Many teachers like to introduce the Bohr atom toward the end of an introductory physics course. This is an excellent idea, given the historic importance of Bohr’s 1913 work, which provided the bridge from Planck’s quantized interaction of matter and radiation (1900) to the full theory of quantum mechanics (1925-28). Unfortunately, the version of the Bohr atom that appears in many textbooks and is no doubt often presented to students is more wrong than right and may leave both teachers and students wondering why, more than a hundred years later, it is still being taught. This “pedagogic” version postulates that an electron in a stationary state moves in a circular orbit with an angular momentum that is an integral multiple of h/2π (L = nh/2π = nħ)—ħ for the lowest-energy state, 2ħ for the next state, and so on. This picture of the hydrogen atom is wrong in two senses. First it doesn’t conform to our present understanding of the hydrogen atom. This, in itself, is not a reason to scrap it, for the historical development of quantum physics is certainly of interest. But second, it doesn’t conform to the essence of what Bohr actually did. That is a reason not to teach about circular orbits and L = nħ.

The Physics TeacherOct 19, 20187 citations

Niels Bohr’s Times

A. Pais

Abstract The life of Niels Bohr spans times of revolutionary change in science itself as well as in its impact on society. As the curtain rises, the reality of atoms is still under debate, the structure of atoms still a matter of conjecture, the atomic nucleus is not yet discovered, practical applications of atomic energy, for good or evil, are not even visible on the far horizon. All that changed during Bohr’s life, much of it under his own influence. He was the first to understand how atoms are put together, he played a leading role in the development of the theory of the atomic nucleus, and he was the godfather of nuclear medicine. He was also th first to bring to the attention of leading statesmen the need for openness betwe1:m West and East, a need resulting from the advent of formidable new weapdms developed during and after World War II. Time and again he would stress that openness was essential for political world stability.Even more profound than new discoveries and perceptions regarding the structure of matter are new physical laws discovered in that same period. Here the key concepts are relativity theory and quantum theory. Bohr was the principal figure in elucidating the revisions of the philosophical foundations of physics needed for a comprehension of quantum phenomena. I have been told that Vladimir Horowitz once commented on Mozart’s music that it is too easy for beginners and too hard for experts. The same can be said of quantum physics. In this book I attempt to outline for beginners how most experts think about quantum theory.

Oct 17, 1991384 citations

Certain About Uncertainty

M. Grant Norton

One hundred years ago the physics that would be necessary to understand how quantum computers work, much less how to build them, did not exist. In the early 1920s electrons were viewed as tiny negatively charged particles—microscopically small spheres—with energies and locations within an atom that were well defined. In Niels Bohr’s Nobel-prize-winning atomic model, electrons moved in orbits around the nucleus with their energy and position both known with, to many scientists, reassuring certainty. Quantum computers rely for their operation on the uncertainty, the “weirdness”, that happens on the atomic scale and below.

Springer eBooksJan 1, 20231 citation

The philosophical writings of Niels Bohr

N. David Mermin

Once I tried to teach some quantum mechanics to a class of law students, philosophers, and art historians. As an advertisement for the course I put together the most sensational quotations I could collect from the most authoritative practitioners of the subject. Heisenberg was a goldmine: “The concept of the objective reality of the elementary particles has thus evaporated…”; “the idea of an objective real world whose smallest parts exist objectively in the same sense as stones or trees exist, independently of whether or not we observe them … is impossible …” Feynman did his part too: “I think I can safely say that nobody understands quantum mechanics.” But I failed to turn up anything comparable in the writings of Bohr. Others attributed spectacular remarks to him, but he seemed to take pains to avoid any hint of the dramatic in his own writings. You don't pack them into your classroom with “The indivisibility of quantum phenomena finds its consequent expression in the circumstance that every definable subdivision would require a change of the experimental arrangement with the appearance of new individual phenomena,” or “the wider frame of complementarity directly expresses our position as regards the account of fundamental properties of matter presupposed in classical physical description but outside its scope.” I was therefore on the lookout for nuggets when I sat down to review these three volumes – a reissue of Bohr's collected essays on the revolutionary epistemological character of the quantum theory and on the implications of that revolution for other scientific and non-scientific areas of endeavor (the originals first appeared in 1934, 1958, and 1963.)

Cambridge University Press eBooksMar 15, 1990324 citations

The Arrival of Bohr’s Atomic Theory

David K. Ferry

The aim of Niels Bohr’s “great” paper was to try to explain how Ernest Rutherford’s planetary model of the atom could exist. Bohr never used the words “quantum jump” in the paper, but it became very much in vogue shortly after this. Max Planck and even A. Einstein had not yet made the full evolution beyond classical physics, and the purely classical atomic views of Rutherford and H. Nagaoka did not provide the explanation of the absorption and emission spectra of hydrogen. In truth, Bohr’s “theory” consisted of a very few equations, with very great assumptions. As de Broglie’s work became known, he was hailed for his advances and he would join the list of Nobel Prizes for advances in quantum theory. Wolfgang Pauli did not particularly like the wave and particle approach that de Broglie introduced with his pilot waves in 1924, and would forcefully express these objections a few years later at the Solvay conference.

Jan 2, 20190 citations