The exact agreement between the Sommerfeld and Dirac results for the energy levels of the relativistic hydrogen atom (the “Sommerfeld Puzzle”) is analyzed and explained.

Concentrating upon applications that are most relevant to modern physics, this valuable book surveys variational principles and examines their relationship to dynamics and quantum theory. Stressing the history and theory of these mathematical concepts rather than the mechanics, the authors provide many insights into the development of quantum mechanics and present much hard-to-find material in a remarkably lucid, compact form. After summarizing the historical background from Pythagoras to Francis Bacon, Professors Yourgrau and Mandelstram cover Fermat's principle of least time, the (...) principle of least action of Maupertuis, development of this principle by Euler and Lagrange, and the equations of Lagrange and Hamilton. Equipped by this thorough preparation to treat variational principles in general, they proceed to derive Hamilton's principle, the Hamilton-Jacobi equation, and Hamilton's canonical equations. An investigation of electrodynamics in Hamiltonian form covers next, followed by a resume of variational principles in classical dynamics. The authors then launch into an analysis of their most significant topics: the relation between variational principles and wave mechanics, and the principles of Feynman and Schwinger in quantum mechanics. Two concluding chapters extend the discussion to hydrodynamics and natural philosophy. Professional physicists, mathematicians, and advanced students with a strong mathematical background will find this stimulating volume invaluable reading. Extremely popular in its hardcover edition, this volume will find even wider appreciation in its first fine inexpensive paperbound edition. (shrink)

One of the popular realist responses to the pessimistic meta-induction is the ‘selective’ move, where a realist only commits to the ‘working posits’ of a successful theory, and withholds commitment to ‘idle posits’. Antirealists often criticise selective realists for not being able to articulate exactly what is meant by ‘working’ and/or not being able to identify the working posits except in hindsight. This paper aims to establish two results: sometimes a proposition is, in an important sense, ‘doing work’, and yet (...) does not warrant realist commitment, and the realist will be able to respond to PMI-style historical challenges if she can merely show that certain selected posits do not require realist commitment. These two results act to significantly adjust the dialectic vis-à-vis PMI-style challenges to selective realism. (shrink)

A success-to-truth inference has always been at the heart of scientific realist positions. But all attempts to articulate the inference have met with very significant challenges. This paper reconstructs the evolution of this inference, and brings together a number of qualifications in an attempt to articulate a contemporary success-to-truth inference which is realistic. I argue that this contemporary version of the inference has a chance, at least, of overcoming the historical challenges which have been proffered to date. However, there is (...) a price to pay: the developments which help the realist answer the historical challenges also serve to increase the number of non-historical challenges. (shrink)

Two successes of old quantum theory are particularly notable: Bohr’s prediction of the spectral lines of ionised helium, and Sommerfeld’s prediction of the fine-structure of the hydrogen spectral lines. Many scientific realists would like to be able to explain these successes in terms of the truth or approximate truth of the assumptions which fuelled the relevant derivations. In this paper I argue that this will be difficult for the ionised helium success, and is almost certainly impossible for the fine-structure success. (...) Thus I submit that the case against the realist’s thesis that success is indicative of truth is marginally strengthened. (shrink)

This paper takes another look at a case study which has featured prominently in a variety of arguments for rival realist positions. After critically reviewing the previous commentaries of the theory shift that took place in the transition from Fresnel’s ether to Maxwell’s electromagnetic theory of optics, it will defend a slightly different reading of this historical case study. Central to this task is the notion of explanatory approximate truth, a concept which must be carefully analysed to begin with. With (...) this notion properly understood, it will be finally argued, the popular Fresnel-Maxwell case study points towards a novel formulation of scientific realism. (shrink)

Selective scientific realists disagree on which theoretical posits should be regarded as essential to the empirical success of a scientific theory. A satisfactory account of essentialness will show that the (approximate) truth of the selected posits adequately explains the success of the theory. Therefore, (a) the essential elements must be discernible prospectively; (b) there cannot be a priori criteria regarding which type of posit is essential; and (c) the overall success of a theory, or ‘cluster’ of propositions, not only individual (...) derivations, should be explicable. Given these desiderata, I propose a “unification criterion” for identifying essential elements. (shrink)

Much debate has ensued regarding the challenge to scientific realism provided by consideration of certain problematic episodes of theory change in the history of science. This paper contends that there is an interesting case which has been overlooked in this debate, namely the prediction of the positron by Dirac from his ‘hole’ theory, and its subsequent replacement by a theory which failed to contain a central, and essential, theoretical posit: the ‘Dirac sea’ of negative energy electrons. Accounting for this case (...) with the ‘divide and conquer’ strategy of contemporary scientific realism proves particularly troublesome, even for the structural realist. (shrink)

One way to characterize dispositions is to take them to be reducible to categorical properties plus experimental arrangements. We argue that this view applied to Bohm 's ontological interpretation of quantum theory provides a good picture of the unremarkable nature of spin in that interpretation, and so explains how a simple realism of possessed values may be retained in the face of Kochen and Specker's theorem. With this in mind we discuss Redhead's influential analysis of Kochen and Specker's theorem which (...) does nor appear to allow for the above view. (shrink)

The most influential arguments for scientific realism remain centrally concerned with an inference from scientific success to the approximate truth of successful theories. Recently, however, and in response to antirealists' objections from radical discontinuity within the history of science, the arguments have been refined. Rather than target entire theories, realists narrow their commitments to only certain parts of theories. Despite an initial plausibility, the selective realist strategy faces significant challenges. In this article, I outline four prerequisites for a successful selective (...) realist defence and argue that adopting a comparative sense of success both satisfies those requirements and partially in consequence provides a more compelling, albeit more modest, realist thesis. (shrink)

Scientific realism is the position that success of a scientific theory licenses an inference to its approximate truth. The argument from pessimistic meta-induction maintains that this inference is undermined due to the existence of theories from the history of science that were successful, but false. I aim to counter pessimistic meta-induction and defend scientific realism. To do this, I adopt a notion of success that admits of degrees, and show that our current best theories enjoy far higher degrees of success (...) than any of the successful, but refuted theories of the past. (shrink)

means exhaust the insults. This is unfortunate as their attitude turns a useful book, with valuable contributions from a number of writers, into a polemic.

Structural realists of nearly all stripes endorse the structural continuity claim. Roughly speaking, this is the claim that the structure of successful scientific theories survives theory change because it has latched on to the structure of the world. In this paper I elaborate, elucidate and modify the structural continuity claim and its associated argument. I do so without presupposing a particular conception of structure that favours this or that kind of structural realism. Instead I focus on how structural realists can (...) best account for the neutrally formulated historical facts. The result, I hope, crystallises some of the shared commitments, desiderata and limits of structural realists. (shrink)