Since its inception in the late 1920s and 30s, the main problem of quantum electrodynamics had been that any interaction or scattering event involved processes of a higher order that arose from vacuum polarization, the creation and subsequent annihilation of particle-antiparticle pairs, and the mutual interactions of all those short-lived entities.1 These processes posed two kinds of conceptual problems. First, they were not detectable individually, but had a measurable effect on the energy of the overall process. Even in simple quantum (...) systems, such as the hydrogen atom, they showed up, for instance, in the form of a further splitting up of spectral lines, most prominently the Lamb shift and measurements of... (shrink)
The present paper investigates why logical empiricists remained silent about one of the most philosophy-laden matters of theoretical physics of their day, the principle of least action (PLA). In the two decades around 1900, the PLA enjoyed a remarkable renaissance as a formal unification of mechanics, electrodynamics, thermodynamics, and relativity theory. Taking Ernst Mach's historico-critical stance, it could be liberated from much of its physico-theological dross. Variational calculus, the mathematical discipline on which the PLA was based, obtained a new rigorous (...) basis. These three developments prompted Max Planck to consider the PLA as formal embodiment of his convergent realist methodology. Typically rejecting ontological reductionism, David Hilbert took the PLA as the key concept in his axiomatizations of physical theories. It served one of the main goals of the axiomatic method: ''deepening the foundations.'' Although Moritz Schlick was a student of Planck's, and Hans Hahn and Philipp Frank enjoyed close ties to Gottingen, the PLA became a veritable Shibboleth to them. Rather than being worried by its historical connections with teleology and determinism, they erroneously identified Hilbert's axiomatic method tout court with Planck's metaphysical realism. Logical empiricists' strict containment policy against metaphysics required so strict a separation between physics and mathematics to exclude even those features of the PLA and the axiomatic method not tainted with metaphysics. (shrink)
The paper studies the topography of the model landscape of the physics in the Higgs sector both within the Standard Model of Elementary Particle Physics and beyond in the months before the discovery of a SM Higgs boson. At first glance, this landscape appears fragmented into a large number of different models and research communities. But it also clusters around certain guiding ideas, among them supersymmetry or dynamical symmetry breaking, in which representative and narrative features of the models are combined. (...) These models do not stand for themselves, waiting to be experimentally confirmed and elevated to the status of theory. Rather do they, quite in the sense advocated by Morgan and Morrison, enjoy a far-reaching autonomy. Typically models in the Higgs sector entertain three types of mediating relationships. First, they mediate between the SM and the data in those instances where the SM contains some uncertainty in the values of its basic parameters. Second, they mediate between BSM physics and the data by instantiating the core ideas behind these often speculative generalizations of the SM as stories—in Hartmann’s sense—that motivate or justify the respective model. Third, the fact that Higgs models within BSM physics reproduce the SM predictions in the low-energy limit functions as a consistency constraint that does not involve any additional autonomy. Due to the second type of mediating relationship, the representative features of Higgs models BSM are complex. (shrink)
The present paper studies a specific way of addressing the question whether the laws involving the basic constituents of nature are statistical. While most German physicists, above all Planck, treated the issues of determinism and causality within a Kantian framework, the tradition which I call Vienna Indeterminism began from Mach’s reinterpretation of causality as functional dependence. This severed the bond between causality and realism because one could no longer avail oneself of a priori categories as a criterion for empirical reality. (...) Hence, an independent reality criterion had to be sought, a problem which all three physicists to be studied solved in different ways that were mainly conditioned by their different concepts of probability. In order to prevent a dissipation of intuited facts, Mach had to resort to a principle of unique determination as his reality criterion, especially when discussing the Principle of Least Action. Giving theories more independence, Boltzmann understood atomism as property reduction to precisely defined theoretical entities and their interactions. While this served as a relative reality criterion, he also advocated a constructivist one because atomism was already implied by our finitary reasoning power. Finally, Exner contemplated the idea that all apparently deterministic laws are only a macroscopic limit of an irreducible indeterminism, because by adopting the frequency interpretation, observable collectives could be considered as the real basic entities. (shrink)
... of Quantum Physics Book Editors Miklós Rédei1 Michael Stöltzner2 Eötvös University, Budapest, Hungary Institute Vienna Circle, Vienna, University of Salzburg, Vienna, Austria ISSN 09296328 ISBN 9789048156511 ISBN 9789401720120 ...
: Our paper discusses the epistemic attitudes of particle physicists on the discovery of the Higgs boson at the Large Hadron Collider. It is based on questionnaires and interviews made shortly before and shortly after the discovery in 2012. We show, to begin with, that the discovery of a Standard Model Higgs boson was less expected than is sometimes assumed. Once the new particle was shown to have properties consistent with SM expectations – albeit with significant experimental uncertainties –, there (...) was a broad agreement that ‘a’ Higgs boson had been found. Physicists adopted a two-pronged strategy. On the one hand, they treated the particle as a SM Higgs boson and tried to establish its properties with higher precision; on the other hand, they searched for any hints of physics beyond the SM. This motivates our first philosophical thesis: the Higgs discovery, being of fundamental importance and establishing a new kind of particle, represented a crucial experiment if one interprets this notion in an appropriate sense. By embedding the LHC into the tradition of previous precision experiments and the experimental strategies thus established, underdetermination and confirmational holism are kept at bay. Second, our case study suggests that criteria of theory preference should be understood as epistemic and pragmatic values that have to be weighed in factual research practice. The Higgs discovery led to a shift from pragmatic to epistemic values as regards the mechanisms of electroweak symmetry breaking. Complex criteria, such as naturalness, combine epistemic and pragmatic different values, but are coherently applied by the community. (shrink)
Papers advocating a hidden-variable interpretation of quantum mechanics typically begin by emphasizing that John von Neumann’s no-go theorem does not apply to them. If authors are ontologically minded, their criticism also takes aim at his theory of measurement as expressed in his seminal 1932 book Mathematical Foundations of Quantum Mechanics Additionally, David Bohm and Basil Hiley have recently argued that “in so far as von Neumann effectively gave the quantum state a certain ontological significance, the net result was to produce (...) a confused and unsatisfactory ontology. This ontology is such that the collapse of the wave function must also have an ontological significance.”. (shrink)
On December 10th, 1947, John von Neumann wrote to the Spanish translator of his Mathematical Foundations of Quantum Mechanics: 1Your questions on the nature of mathematical physics and theoretical physics are interesting but a little difficult to answer with precision in my own mind. I have always drawn a somewhat vague line of demarcation between the two subjects, but it was really more a difference in distribution of emphases. I think that in theoretical physics the main emphasis is on the (...) connection with experimental physics and those methodological processes which lead to new theories and new formulations, whereas mathematical physics deals with the actual solution and mathematical execution of a theory which is assumed to be correct per se, or assumed to be correct for the sake of the discussion. In other words, I would say that theoretical physics deals rather with the formation and mathematical physics rather with the exploitation of physical theories. However, when a new theory has to be evaluated and compared with experience, both aspects mix. (shrink)
Commenting on Atkinson 's paper I argue that leading to a successful real experiment is not the only scale on which a thought experiment's value is judged. Even the path from the original EPR thought experiment to Aspect's verification of the Bell inequalities was long-winded and involved considerable input from the sides of technology and mathematics. Von Neumann's construction of hidden variables was, moreover, a genuinely mathematical thought experiment that was successfully criticized by Bell. Such thought experiments are also possible (...) in string theory, where any empirical corroboration seems to be out of reach. Yet appraising mathematical thought experiments and their contribution to physical thought experiments requires a dynamical account which in the spirit of Mach and Lakatos attributes due weight to informal mathematical reasoning or empirical intuition. (shrink)
Paces of Rationality in the History of Science: On the Temporal Structures of the Quantum Revolution. I argue that the Kuhnian picture of scientific revolutions must be modified by introducing various levels of historical reality and reference points for rational justification in order to permit the constant movement back and forth between long shots and close-ups that is indispensable in the history of science. Such an account makes it possible to describe a scientific revolution not as a simultaneous break on (...) all levels, but as a sequence of ruptures on different levels, in which some levels allow the formulation of the new points of view or a justification of the transition. The proposed account appears reconcilable both with Michael Friedman's recent philosophical analysis of the dynamics of reason, even though it also admits of social and technological levels that are not representing a constitutive a priori, and Michel Foucault's archeology of nature, which does not contradict the fact that in studying the history of physical theory one typically finds precisely formulated and well-separated levels of knowledge. It is ironic that Kuhn's original account, which helped to shape the ‘new epistemology’, is still largely indebted to the Logical Empiricists' conception of a single linguistic framework, the establishment of which is merely a matter of convention and pragmatics. At the example of Mara Beller's assessment of the quantum revolution. I argue that the Kuhnian picture represents an obstacle against assessing one particular trait of the German physics of the 1920s, the important formative part played by philosophical convictions of the German physicist-philosophers. (shrink)
Applied mathematics often operates by way of shakily rationalizedexpedients that can neither be understood in a deductive-nomological nor in an anti-realist setting.Rather do these complexities, so a recent paper of Mark Wilson argues, indicate some element in ourmathematical descriptions that is alien to the physical world. In this vein the mathematical opportunistopenly seeks or engineers appropriate conditions for mathematics to get hold on a given problem.Honest mathematical optimists, instead, try to liberalize mathematical ontology so as to include all physicalsolutions. Following (...) John von Neumann, the present paper argues that the axiomatization of a scientifictheory can be performed in a rather opportunistic fashion, such that optimism and opportunism appear as twomodes of a single strategy whose relative weight is determined by the status of the field to beinvestigated. Wilson's promising approach may thus be reformulated so as to avoid precarious talk about a physicalworld that is void of mathematical structure. This also makes the appraisal of the axiomatic method inapplied matthematics less dependent upon foundationalist issues. (shrink)
The relation between Ernst Mach and Albert Einstein is probably one of the most debated issues in the history of twentieth century physics. For many physicists general relativity is the paradigm ofhow a mature theory should look. This opinion was supported by philosophers, in particular logical empiricists, to whom general relativity was the main touchstone of their principles of theory formation. Mach’s principle penetrates all three domains. Einstein’s first formulation of it in 1918 read: “The G-field is without remainder determined (...) by the masses of the bodies. Since mass and energy are... the same.. .this therefore entails that the G-field be condi tioned and determined by the energy tensor”. (shrink)
This paper argues that there is no single universal conception of scientific explanation that is consistently employed throughout the whole domain of Higgs physics—ranging from the successful experimental search for a standard model Higgs particle and the hitherto unsuccessful searches for any particles beyond the standard model, to phenomenological model builders in the Higgs sector and theoretical physicists interested in how the core principles of quantum field theory apply to spontaneous symmetry breaking and the Higgs mechanism. Yet the coexistence of (...) deductive-statistical, unificationist, model-based, and statistical-relevance explanations does not amount to a fragmentation of the discipline, but allows elementary particle physicists to simultaneously pursue a plurality of research strategies and keep the field together by joint convictions about the SM and shared explanatory ideals. These convictions include that the SM both represents a successful explanation of the available particle data and contains aspects in need of further explanation. Especially in the domain of BSM physics, explanatory ideals typically appear as stories motivating the different models and linking them to the whole of the discipline. (shrink)
The documents selected for publication in this book have never been published before. All are deposited in the von Neumann Archive of the Manuscript Division of the Library of Congress . The rich von Neumann Archive contains numerous documents that have never been published in any form. The documents included in this volume have been selected on the basis of their direct relevance to von Neumann’s work on the foundations of quantum physics, the main topic of this volume. Three kinds (...) of documents are published here: letters by and to von Neumann, von Neumann’s 1954 address to the International Congress of Mathematicians in Amsterdam, and the unpublished manuscript “Quantum mechanics of infinite systems” authored by von Neumann. The comments below put these documents in context. (shrink)
After the death of Otto Neurath in 1945, Philipp Frank appeared to be the most talented organizer of the Vienna Circle in exile. From his new position at Harvard he organized many of the Unity of Science meetings and served from 1947 on as president of the Institute for the Unity of Science. It is well known that in 1929 he had organized the famous first meeting on Erkenntnislehre der exakten Wissenschaften in Prague, at which the Vienna Circle went public. (...) Frank later wrote on this:We wanted to reach a large audience. The ordinary regular philosophy meetings followed the traditional lines and would hardly have given us enough scope. By a happy coincidence I was just in 1929 arranging a meeting of the physicists and mathematicians from the German-speaking regions in Central...The German Physical Society, which was the official sponsor of this meeting, did not particularly like the idea of combining this serious meeting with such a foolish thing as philosophy. However, I was the chairman of the local committee in Prague and they could not refuse my serious...Some scientists wanted to minimize our program and predicted that they would have no audience from the ranks of exact scientists. As a matter of fact, our addresses had a larger audience than papers on special scientific problems. I had prepared an elaborate paper that was intended to give the scientists a kind of preview of our ideas and to prove that the new line in philosophy is the necessary result of the new trends in physics, particularly the theory of relativity and the quantum...Some friends cautioned me not to speak too bluntly. The audience, which consisted mostly of German scientists, knew litte about...My wife said to me after the lecture: “It was weird to...Everything seemed to vanish without a trace.”There is no doubt that quite a few people in the audience were shocked by my blunt statements that modem science is incompatible with the traditional systems of philosophy. Probably, most of the scientists had not been accustomed to thinking of philosophy and science as a coherent system of thought...After the meeting, however, our committee received a great many letters from scientists who expressed their great satisfaction that an attempt has been made toward a coherent world conception without contradictions between science and philosophy. (shrink)
John von Neumann was, undoubtedly, one of the true scientific geniuses of the 20th century. The main fields to which he contributed include different disciplines of pure and applied mathematics, mathematical and theoretical physics, logic, theoretical computer science and computer design. Von Neumann was also actively involved in politics, science management, served on a number of commissions and advisory committees and had a major impact on U.S. government decisions during, and especially after, the Second World War.
Quantum theorists silently slaughter cats in tightly closed boxes. For matters of consistency, general relativists prefer family affairs instead. They travel back in time to murder their grandfathers before they themselves were born. John Earman’s new book brings good news for the elder generation: Grandfathers do not figure so prominently in a critical account of general relativity that any such experiment will ever pass an ethics commission.
Rudolf Carnap and Hans Reichenbach can be considered as the most influential protagonists-in-exile of the scientific philosophy that arose in the twenties and early thirties under the headings Wissenschaftliche Weltauffassung and Wissenschaftliche Philosophie. Both were born in 1891 — as was a generally forgotten member of the Vienna Circle: Edgar Zilsel.
Many physicists view the most sublime task of physics in presenting some day a world formula or a simple Theory of Everything that accounts for all major physical theories and from which everything follows by pure deduction.1 This striving for universality can look back on a long history, which contains the failed attempts to incorporate electrodynamics into universal mechanics, Einstein’s einheitliche Feldtheorie and Heisenberg’s explicit proposal of an Urgleichung. Those attempts were encouraged by the success of general relativity, which embraced (...) classical mechanics and Newtonian gravity as well defined limits. A decade later quantum mechanics was given its final shape, which allowed the explanation of all atomic phenomena known up to then and contained classical mechanics as its macroscopic limit at least in the stochastic interpretation, i.e. comparing both as theories of measurement. After the success of gauge theories in elementary particle physics, the search for a fundamental simple equation was replaced by the search for a basic symmetry group that described all fundamental interactions apart from gravity. It resulted in the famous gauge group of the Standard Model SU × SU L × U , which comprises the strong, the weak and the electromagnetic interaction. But the fact that the Standard Model contains 18 parameters, which have to be introduced from outside, inspired the search for a larger unifying gauge group. These Grand Unified Theories tried to derive some of the parameters of the Standard Model from more fundamental gauge symmetries. With the rise of string theory, which intends to include gravity as well, a new term popped up to express the old claims: Theory of Everything. (shrink)
During my first year of philosophy study at a German university I shared the prejudice of my colleagues that positivist texts are tedious if not boring, at least compared to Schopenhauer or Nietzsche, to Sartre or other French philosophers. Here is a book that shows the opposite and succeeds in keeping the esprit of an essay over 233 pages. Parrini’s use of the word ‘essay’ alludes to Hume’s Essays, more generally to the English tradition rather than to those contemporaries to (...) whom philosophy is nothing but an essay. Unfortunately, Parrini pays an unnecessary high price for this form when the book’s only footnote informs us that “Reasons of expressive form after all have led me not to burden the text with the usual references to authors and works used. I apologize to the reader. ”1 The expert will easier accept this excuse and, perhaps, enjoy the unencumbered reading, although, as a matter of fact, some footnote-like hints to other authors or even Parrini’s own works are entirely useless without any reference. But, the omittance partly spoils one great merit of the book. As large parts of it are self-contained and Parrini succeeds in making most technical points quite transparent, the essay appears to me very readable for students. To him or her, hardly reading footnotes when going through it first, it becomes almost impossible to penetrate further into ‘positive philosophy’. It would have been much more profitable to the freshmen to supplement the book by a two-page bibliography containing the basic references. The English translation to appear soon will contain references and bibliography in the standard fashion. It is a pity, that unlike the Italian original only few students will be able to afford this fascinating book due to its high price. (shrink)
On Two Types of Realism in Quantum Theory. Current realist approaches to the foundations of quantum theory emphasize the dichotomy between (Copenhagen) positivism and ‘beable’-realism. Recently it was even attempted to turn this picture into two (equally possible) histories in order to legitimate Bohmian Mechanics as a viable alternative. This paper argues that this dichotomy is philosophically inadequate and historically questionable by embedding it into the philosophical discussion on positivism and realism that has taken place since the 1920s. Logical Empiricists (...) back then advocated empirical realism and contrasted it to absolutistic metaphysical realism. From this viewpoint David Bohm's ‘beable’-realism combines elements of Mach's sensualism with a pre-Kantian metaphysics. As Wesley Salmon's position shows, empirical realism can become quite pronounced without relapsing into Bohmian philosophy. Instead it arrives close to the GRWP-interpretation. Hence, when Bernard d'Espagnat binds both together as ‘ontological interpretations’, he blurs the borderline between empirical and metaphysical realism that his Veiled Reality has set out to draw, quite in concordance with Logical Empiricism. (shrink)
An Encyclopedia for the Empire. In the preface to the universal encyclopedia Die Kultur der Gegenwart , the editor-in-chief Paul Hinneberg places his project – not openly but nevertheless unequivocally – in the tradition of the French Encyclopédie that Diderot and d'Alembert had organized from 1751 until 1765. The attempt to accomplish anew such a large-scale project and, in this way, to win the German Empire the kind of intellectual leadership which the Encyclopédie, in historical retrospect, had achieved for the (...) epoch of Enlightenment, required to convince the leading scholars, scientists, and technicians of the nation to participate in the endeavor and to assemble their contributions under a common systematic agenda through which this universal encyclopedia would distinguish itself from all dictionaries and disciplinary encyclopedias. While the Encyclopédie followed to a large extent an empiricist philosophy, Hinneberg trusted in the integrative function of the concept of culture and the ability of his contributors to elucidate the history of their respective disciplines and to connect them with neighboring fields of culture. The present contributions argues that although, from a philosophical point of view, the historicist tack taken by Hinneberg makes the concept of culture quite blurry, it nevertheless provides enough cohesive structure such that the work, even though unfinished as a consequence of war and inflation, represents a faithful picture of its epoch that Hinneberg understands as an epoch of transition. (shrink)