Holism, Physical Theories and Quantum Mechanics

Motivated by the question what it is that makes quantum mechanics a holistic theory (if so), I try to define for general physical theories what we mean by `holism'. For this purpose I propose an epistemological criterion to decide whether or not a physical theory is holistic, namely: a physical theory is holistic if and only if it is impossible in principle to infer the global properties, as assigned in the theory, by local resources available to an agent. I propose that these resources include at least all local operations and classical communication. This approach is contrasted with the well-known approaches to holism in terms of supervenience. The criterion for holism proposed here involves a shift in emphasis from ontology to epistemology. I apply this epistemological criterion to classical physics and Bohmian mechanics as represented on a phase and configuration space respectively, and for quantum mechanics (in the orthodox interpretation) using the formalism of general quantum operations as completely positive trace non-increasing maps. Furthermore, I provide an interesting example from which one can conclude that quantum mechanics is holistic in the above mentioned sense, although, perhaps surprisingly, no entanglement is needed.Comment: Published versio

Monogamy of Correlations vs. Monogamy of Entanglement

A fruitful way of studying physical theories is via the question whether the possible physical states and different kinds of correlations in each theory can be shared to different parties. Over the past few years it has become clear that both quantum entanglement and non-locality (i.e., correlations that violate Bell-type inequalities) have limited shareability properties and can sometimes even be monogamous. We give a self-contained review of these results as well as present new results on the shareability of different kinds of correlations, including local, quantum and no-signalling correlations. This includes an alternative simpler proof of the Toner-Verstraete monogamy inequality for quantum correlations, as well as a strengthening thereof. Further, the relationship between sharing non-local quantum correlations and sharing mixed entangled states is investigated, and already for the simplest case of bi-partite correlations and qubits this is shown to be non-trivial. Also, a recently proposed new interpretation of Bell's theorem by Schumacher in terms of shareability of correlations is critically assessed. Finally, the relevance of monogamy of non-local correlations for secure quantum key distribution is pointed out, although, and importantly, it is stressed that not all non-local correlations are monogamous.Comment: 12 pages, 2 figures. Invited submission to a special issue of Quantum Information Processing. v2: Published version. Open acces

Is Quantum Mechanics Technologically Inadequate?

In a recent issue of the British Journal for the Philosophy of Science (2005), P.E. Vermaas claims to have demonstrated that standard quantum mechanics is technologically inadequate in that it violates the `technical functions condition'. We argue that this claim is false because based on a `narrow' interpretation of this technical functions condition that Vermaas can only accept on pain of contradiction. We also argue that if, in order to avoid this contradiction, the technical functions condition is interpreted `widely' rather than `narrowly', then Vermaas his argument for his claim collapses. The conclusion is that Vermaas' claim that standard quantum mechanics is technologically inadequate evaporates

Can quantum theory and special relativity peacefully coexist?

This white paper aims to identify an open problem in ‘Quantum Physics and the Nature of Reality’—namely whether quantum theory and special relativity are formally compatible—, to indicate what the underlying issues are, and put forward ideas about how the problem might be addressed

No-signaling, Perfect Bipartite Dichotomic Correlations and Local Randomness

The no-signaling constraint on bi-partite correlations is reviewed. It is shown that in order to obtain non-trivial Bell-type inequalities that discern no-signaling correlations from more general ones, one must go beyond considering expectation values of products of observables only. A new set of nontrivial no-signaling inequalities is derived which have a remarkably close resemblance to the CHSH inequality, yet are fundamentally different. A set of inequalities by Roy and Singh [29] and Avis et al.. [1], which is claimed to be useful for discerning no-signaling correlations, is shown to be trivially satisfied by any correlation whatsoever. Finally, using the set of newly derived no-signaling inequalities a result with potential cryptographic consequences is proven: if different parties use identical devices, then, once they have perfect correlations at spacelike separation between dichotomic observables, they know that because of no-signaling the local marginals cannot but be completely rando

“So you confirmed, replicated and emptied your file-drawer… now what?” A Structural Realist’s Guide to Theory Evaluation in Psychological Science

The papers in the special issue of PPS on the origins and possible resolution of the crisis of confidence in psychological science hardly mention the word theory. We argue that all the excellent suggestions to reform the discipline will be in vain if it does not begin a discussion about the way it evaluates and revises its theories. We diagnose theory evaluation as afflicted with three serious symptoms and provide exemplary examples from the scientific record of psychology to illustrate them. The first symptom is the interpretation fallacy, of which the very critical commentaries received by proponents of the complex systems approach about their efforts to study psychological phenomena, represent an exemplary case (e.g. Wagenmakers, van der Maas, & Farrell, 2012). The second is the empiricist’s blind-spot. We will discuss it in the context of the plethora of theories that have been posited by the psychological and life sciences about the ætiology of developmental dyslexia. We especially discuss the apparent inability of the huge empirical record of high quality behavioral, neuroscientific and genetic data to resolve any theoretical dispute (e.g. Ramus & Szenkovits, 2008). The third symptom is the Columbus delusion, of which the recent publication “There is nothing so theoretical as a good method” (Greenwald, 2012) is an excellent example. These symptoms are all related and pertain to the different roles ontology plays in scientific theorizing. Our critical diagnosis is not the end goal of this paper however, we respond to the call to device methods for strong inference (Fiedler, Kutzner, & Krueger, 2012) and provide a practical, but formal approach to theory evaluation known as Structural Realism (cf. Worrall, 1989). In three parts, our Structural Realist’s guide to theorizing about the universe will elaborate on how to deal with theoretical diversity and in the process cure psychological science of its ailment, ensuring it will remain the prime discipline for the scientific study of psychological phenomena in the future

Non-local setting and outcome information for violation of Bell's inequality

Bell's theorem is a no-go theorem stating that quantum mechanics cannot be reproduced by a physical theory based on realism, freedom to choose experimental settings and two locality conditions: setting (SI) and outcome (OI) independence. We provide a novel analysis of what it takes to violate Bell's inequality within the framework in which both realism and freedom of choice are assumed, by showing that it is impossible to model a violation without having information in one laboratory about both the setting and the outcome at the distant one. While it is possible that outcome information can be revealed from shared hidden variables, the assumed experimenter's freedom to choose the settings ensures that the setting information must be non-locally transferred even when the SI condition is obeyed. The amount of transmitted information about the setting that is sufficient to violate the CHSH inequality up to its quantum mechanical maximum is 0.736 bits