This is a book about the Hilbert space formulation of quantum mechanics and its measurement theory. It contains a synopsis of what became of the Mathematical Foundations of Quantum Mechanics since von Neumann's classic treatise with this title. Fundamental non-classical features of quantum mechanics-indeterminacy and incompatibility of observables, unavoidable measurement disturbance, entanglement, nonlocality-are explicated and analysed using the tools of operational quantum theory. The book is divided into four parts: 1. Mathematics provides a systematic exposition of the Hilbert space and (...) operator theoretic tools and relevant measure and integration theory leading to the Naimark and Stinespring dilation theorems; 2. Elements develops the basic concepts of quantum mechanics and measurement theory with a focus on the notion of approximate joint measurability; 3. Realisations offers in-depth studies of the fundamental observables of quantum mechanics and some of their measurement implementations; and 4. Foundations discusses a selection of foundational topics (quantum-classical contrast, Bell nonlocality, measurement limitations, measurement problem, operational axioms) from a measurement theoretic perspective. The book is addressed to physicists, mathematicians and philosophers of physics with an interest in the mathematical and conceptual foundations of quantum physics, specifically from the perspective of measurement theory. (shrink)

Mounting evidence suggests that endorsement of psychological continuity and the afterlife increases with age. This developmental change raises questions about the cognitive biases, social representations, and cultural input that may support afterlife beliefs. To what extent is there similarity versus diversity across cultures in how people reason about what happens after death? The objective of this study was to compare beliefs about the continuation of biological and psychological functions after death in Tanna, Vanuatu, and the United States. Children, adolescents, and (...) adults were primed with a story that contained either natural or supernatural cues. Participants were then asked whether or not different biological and psychological processes continue to function after death. We predicted that across cultures individuals would be more likely to endorse the continuation of psychological processes over biological processes and that a theistic prime would increase continuation responses regarding both types of process. Results largely supported predictions; U.S. participants provided more continuation responses for psychological than biological processes following both the theistic and non-theistic primes. Participants in Vanuatu, however, provided more continuation responses for biological than psychological processes following the theistic prime. The data provide evidence for both cultural similarity and variability in afterlife beliefs and demonstrate that individuals use both natural and supernatural explanations to interpret the same events. (shrink)

Noncommuting quantum observables, if considered asunsharp observables, are simultaneously measurable. This fact is exemplified for complementary observables in two-dimensional state spaces. Two proposals of experimentally feasible joint measurements are presented for pairs of photon or neutron polarization observables and for path and interference observables in a photon split-beam experiment. A recent experiment proposed and performed by Mittelstaedt, Prieur, and Schieder in Cologne is interpreted as a partial version of the latter example.

The positive operator (valued) measures (POMs) allow one to generalize the notion of observable beyond the traditional one based on projection valued measures (PVMs). Here, we argue that this generalized conception of observable enables a consistent notion of unsharp reality and with it an adequate concept of joint properties. A sharp or unsharp property manifests itself as an element of sharp or unsharp reality by its tendency to become actual or to actualize a specific measurement outcome. This actualization tendency—or potentiality—of (...) a property is quantified by the associated quantum probability. The resulting single-case interpretation of probability as a degree of reality will be explained in detail and its role in addressing the tensions between quantum and classical accounts of the physical world will be elucidated. It will be shown that potentiality can be viewed as a causal agency that evolves in a well-defined way. (shrink)

Heisenberg's uncertainty principle is usually taken to express a limitation of operational possibilities imposed by quantum mechanics. Here we demonstrate that the full content of this principle also includes its positive role as a condition ensuring that mutually exclusive experimental options can be reconciled if an appropriate trade-off is accepted. The uncertainty principle is shown to appear in three manifestations, in the form of uncertainty relations: for the widths of the position and momentum distributions in any quantum state; for the (...) inaccuracies of any joint measurement of these quantities; and for the inaccuracy of a measurement of one of the quantities and the ensuing disturbance in the distribution of the other quantity. Whilst conceptually distinct, these three kinds of uncertainty relations are shown to be closely related formally. Finally, we survey models and experimental implementations of joint measurements of position and momentum and comment briefly on the status of experimental tests of the uncertainty principle. (shrink)

The possibilities of a realistic interpretation of quantum mechanics are investigated by means of a statistical analysis of experiments performed on the simplest type of quantum systems carrying spin or helicity. To this end, fundamental experiments, some new, for measuring polarization are reviewed and (re)analyzed. Theunsharp reality of spin is essential in the interpretation of some of these experiments and represents a natural motivation for recent generalizations of quantum mechanics to a theory incorporating effect-valued measures as unsharp observables and generalized (...) systems of imprimitivity. (shrink)

The determination of the past and the future of a physical system are complementary aims of measurements. An optimal determination of the past of a system can be achieved by an informationally complete set of physical quantities. Such a set is always strongly noncommutative. An optimal determination of the future of a physical system can be obtained by a Boolean complete set of quantities. The two aims can be reconciled to a reasonable degree with using unsharp measurements.

A coherent account of the connections and contrasts between the principles of complementarity and uncertainty is developed starting from a survey of the various formalizations of these principles. The conceptual analysis is illustrated by means of a set of experimental schemes based on Mach-Zehnder interferometry. In particular, path detection via entanglement with a probe system and (quantitative) quantum erasure are exhibited to constitute instances of joint unsharp measurements of complementary pairs of physical quantities, path and interference observables. The analysis uses (...) the representation of observables as positive-operator-valued measures (POVMs). The reconciliation of complementary experimental options in the sense of simultaneous unsharp preparations and measurements is expressed in terms of uncertainty relations of different kinds. The feature of complementarity, manifest in the present examples in the mutual exclusivity of path detection and interference observation, is recovered as a limit case from the appropriate uncertainty relation. It is noted that the complementarity and uncertainty principles are neither completely logically independent nor logical consequences of one another. Since entanglement is an instance of the uncertainty of quantum properties (of compound systems), it is moot to play out uncertainty and entanglement against each other as possible mechanisms enforcing complementarity. (shrink)

We propose that observables in quantum theory are properly understood as representatives of symmetry-invariant quantities relating one system to another, the latter to be called a reference system. We provide a rigorous mathematical language to introduce and study quantum reference systems, showing that the orthodox “absolute” quantities are good representatives of observable relative quantities if the reference state is suitably localised. We use this relational formalism to critique the literature on the relationship between reference frames and superselection rules, settling a (...) long-standing debate on the subject. (shrink)

The hypotheses of weak and strong objectification of quantum mechanical observables, as well as theoretical arguments and experimental evidence against these hypotheses, are systematically reviewed.

Uncertainty relations and complementarity of canonically conjugate position and momentum observables in quantum theory are discussed with respect to some general coupling properties of a function and its Fourier transform. The question of joint localization of a particle on bounded position and momentum value sets and the relevance of this question to the interpretation of position-momentum uncertainty relations is surveyed. In particular, it is argued that the Heisenberg interpretation of the uncertainty relations can consistently be carried through in a natural (...) extension of the usual Hilbert space frame of the quantum theory. (shrink)

The quantum theory of sequential measurements is worked out and is employed to provide an operational analysis of basic measurement theoretical notions such as coexistence, correlations, repeatability, and ideality. The problem of the operational definition of continuous observables is briefly revisited, with a special emphasis on the localization observable. Finally, a brief overview is given of possible applications of the theory to various fields and problems in quantum physics.

The 2013 Rostock Symposium on Systems Biology and Bioinformatics in Aging Research was again dedicated to dissecting the aging process using in silico means. A particular focus was on ontologies, as these are a key technology to systematically integrate heterogeneous information about the aging process. Related topics were databases and data integration. Other talks tackled modeling issues and applications, the latter including talks focussed on marker development and cellular stress as well as on diseases, in particular on diseases of kidney (...) and skin. (shrink)

The role of completely positive mappings in quantum dynamics and measurement theory is reanalyzed in light of the possibility of a generalized dynamics.

This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberger, to be published by Springer-Verlag.

This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberg, to be published by Springer-Verlag.

This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberger, to be published by Springer-Verlag.

This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberger, to be published by Springer-Verlag.

This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberger, to be published by Springer-Verlag.

This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberger, to be published by Springer-Verlag.

This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberg, to be published by Springer-Verlag.

The question of quantifying the sharpness (or unsharpness) of a quantum mechanical effect is investigated. Apart from sharpness, another property, bias, is found to be relevant for the joint measurability or coexistence of two effects. Measures of bias will be defined and examples given.

The University of Cologne and the international community of researchers in foundations of physics mourn the loss of Peter Mittelstaedt, who passed away on November 21, 2014, after a short period of illness. Peter Mittelstaedt held a chair in theoretical physics at the University of Cologne from 1965 until his retirement in 1995. In addition to his engagement as a scientist and academic teacher he was elected first as Dean of the Faculty of Science and then Rector of the University (...) of Cologne . Subsequently he served as Prorector and Prorector for Research . He was an elected member of l’Académie Internationale de Philosophie des Sciences and founding member and president of the International Quantum Structures Association .Peter Mittelstaedt was born in Leipzig on November 24, 1929. In his childhood home he may already have witnessed the spirit of philosophical discourse about the world-picture of modern physics. For Werner Heis .. (shrink)

ABSTRACTWith over 560 citations reported on Google Scholar by April 2018, a publication by Juslin and Gabrielsson presented evidence supporting performers’ abilities to communicate, with hig...

The problem of the validity and interpretation of the energy-time uncertainty relation is briefly reviewed and reformulated in a systematic way. The Bohr-Einsteinphoton-box gedanken experiment is seen to illustrate the complementarity of energy andevent time. A more recent experiment with amplitude-modulated Mößbauer quanta yields evidence for the genuine quantum indeterminacy of event time. In this way, event time arises as a quantum observable.

The discussion of a particular kind of interpretation of the energy-time uncertainty relation, the “pragmatic time” version of the ETUR outlined in Part I of this work [measurement duration (pragmatic time) versus uncertainty of energy disturbance or measurement inaccuracy] is reviewed. Then the Aharonov-Bohm counter-example is reformulated within the modern quantum theory of unsharp measurements and thereby confirmed in a rigorous way.

The standard model of the quantum theory of measurement is based on an interaction Hamiltonian in which the observable to be measured is multiplied by some observable of a probe system. This simple Ansatz has proved extremely fruitful in the development of the foundations of quantum mechanics. While the ensuing type of models has often been argued to be rather artificial, recent advances in quantum optics have demonstrated their principal and practical feasibility. A brief historical review of the standard model (...) together with an outline of its virtues and limitations are presented as an illustration of the mutual inspiration that has always taken place between foundational and experimental research in quantum physics. (shrink)

Recent advantages in experimental quantum physics call for a careful reconsideration of the measurement process in quantum mechanics. In this paper we describe the structure of the ideal measurements and their status among the repeatable measurements. Then we provide an exhaustive account of the interrelations between repeatability and the apparently weaker notions of value reproducible or first- kind measurements. We demonstrate the close link between repeatable measurements and discrete observables and show how the ensuing measurement limitations for continuous observables can (...) be lifted in a way that is in full accordance with actual experimental practice. We present examples of almost repeatable measurements of continuous observables and some realistic models of weakly disturbing measurements. (shrink)

In a period of over 50 years, Peter Mittelstaedt has made substantial and lasting contributions to several fields in theoretical physics as well as the foundations and philosophy of physics. Here we present an overview of his achievements in physics and its foundations which may serve as a guide to the bibliography (printed in this Festschrift) of his publications. An appraisal of Peter Mittelstaedt’s work in the philosophy of physics is given in a separate contribution by B. Falkenburg.

This is a book review. To be published in Studies in History and Philosophy of Modern Physics.

Es gibt offensichtlich nicht nur Moden der Kleidung, der Frisur oder des Wohnens, sondern auch Moden in den Wissenschaften, in Kunst, Philosophie und vielleicht sogar in der Religion. Das heisst aber gerade in Bereichen, die doch eigentlich 'feste Prinzipien' gegen den Wechsel des Zeitgeistes und der Moden verteidigen. Aber was bedeutet dann in diesen Zusammenhängen "Mode"? Und wie lassen sich solche geistigen Moden erklären? Gehören "Mode" und "Moderne" zusammen? Der vorliegende Band versucht eine systematische Antwort auf diese Fragen, indem er (...) zunächst das Phänomen des Modischen auf seinen offenkundigen Feldern untersucht: den Kleidungsmoden, Wohnmoden, Körpermoden und den Moden in Freizeitgestaltung und Tourismus sowie im Sport. Von hier aus wird nach den spezifisch intellektuellen Moden in den Natur- und Geisteswissenschaften, in der Kunst, in der Philosophie und in der Religion gefragt. Mit Beiträgen von: Georg Bertram, Hubertus Busche, Yvonne Förster, Robert Gugutzer, Rainer Hartmann, Frank Hillebrandt, Paul Hoyningen-Huene, Irene Nierhaus, Daria Pezzoli-Olgiati, Verena Potthoff, Tim Rojek. (shrink)

"Displaying a masterful grasp of the texts, the author shows how otherness forces itself upon the existentialist Sartre, gradually constraining him to modify his understanding of consciousness as omnipotent. The issue is Sartre’s discovery of the social and its conceptual assimilation into his individualistic, consciousness-oriented philosophy." —Thomas R. Flynn "This very successful and accessible scholarly book... is simultaneously a succinct and clear overview of Sartre’s philosophical works.... and a fresh consideration of Sartre’s body of work." —Choice "Busch’s admirably clear (...) and compact discussion is essential reading for Sartre scholars, since it powerfully addresses many issues dividing them... " —Ethics "... a useful overview of the evolution of Sartre’s thought... " —Review of Politics "... a thought provoking reassessment of Sartre's philosophical career." —Man and World "... succinct, richly documented survey... " —International Studies in Philosophy. (shrink)

Abstract As Paul B. Thompson suggests in his recent seminal paper, “‘There’s an App for That’: Technical Standards and Commodification by Technological Means,” technical standards restructure property (and other social) relations. He concludes with the claim that the development of technical standards of commodification can serve purposes with bad effects such as “the rise of the factory system and the deskilling of work” or progressive effects such as how “technical standards for animal welfare… discipline the unwanted consequences of market (...) forces.” In this reply, we want to append several points to his argument and suggest that he rightly points out that standards can promote various goods; however, there are peculiar powers wielded by standardization processes that might profitably be unpacked more systematically than Thompson's article seems to suggest. First, the concealment of the technopolitics around standards is largely due to their peculiar ontological status as recipes for reality. Second, technical standards can and do commit violence against persons, but such violence is often suffered not in the formation of class consciousness, as Marx might have put it, but as a failure to conform to the laws of nature . Content Type Journal Article Category Commentary Pages 1-6 DOI 10.1007/s13347-011-0048-1 Authors Lawrence Busch, Department of Sociology, Michigan State University, 429A Berkey Hall, East Lansing, MI 48824, USA Kyle Powys Whyte, Department of Philosophy, Michigan State University, 503 S. Kedzie Hall, East Lansing, MI 48824, USA Journal Philosophy & Technology Online ISSN 2210-5441 Print ISSN 2210-5433. (shrink)