Olimpia Lombardi

Focusing on Shannon information, this article shows that, even on the basis of the same formalism, there may be different interpretations of the concept of information, and that disagreements may be deep enough to lead to very different conclusions about the informational characterization of certain physical situations. On this basis, a pluralist view is argued for, according to which the concept of information is primarily a formal concept that can adopt different interpretations that are not mutually exclusive, but each useful in a different specific context.

Prigogine afirma que, en presencia de alta inestabilidad (caos), los estados puntuales y las trayectorias lineales en el espacio de las fases se convierten en una falsa idealización. En el presente trabajo se sostiene que: (i) los argumentos de Prigogine en favor de tal tesis no son concluyentes, y (ii) hay buenas razones para retener la postulacion de estados puntuales y trayectorias lineales, en tanto conceptos teóricos legítimos en mecánica estadística.Prigogine asserts that the existence of radical instability (chaos) makes the postulation of pointlike states and linelike trajectories in phase space a false idealization. In this paper we argue that (i) Prigogine’s arguments for this claim are not conclusive, and (ii) there are good reasons for retain the positing of pointlike states and linelike trajectories as a legitimate theoretical posit in statistical mechanics

We propose a new quantum ontology, in which properties are the fundamental building blocks. In this property ontology physical systems are defined as bundles of type-properties. Not all elements of such bundles are associated with definite case-properties, and this accommodates the Kochen and Specker theorem and contextuality. Moreover, we do not attribute an identity to the type-properties, which gives rise to a novel form of the bundle theory. There are no “particles” in the sense of classical individuals in this ontology, although the behavior of such individuals is mimicked in some circumstances. This picture leads in a natural way to the symmetrization postulates for systems of many “identical particles”.

Currently, there are almost as many conceptions of emergence as authors who address the issue. Most literature on the matter focuses either on discussing, evaluating and comparing particular contributions or accounts of emergence, or on assessing a particular case study. Our aim in this paper is rather different. We here set out to introduce a distinction that has not been sufficiently taken into account in previous discussions on this topic: the distinction between inter-domain emergence—a relation between items belonging to different ontic domains—and intra-domain emergence—a relation between items belonging to a same ontic domain. Our final purpose is not to assume and defend a definite stance on emergence, but to stress the relevance of such distinction when attempting to argue for or against emergence, in the first place. We will also address the connections between emergence so distinguished and more general philosophical perspectives, suggesting where would reductionists and pluralists stand with respect to intra- and inter-domain emergence.

El propósito del presente trabajo consiste en abordar la pregunta por la ontología de la química cuántica. Para ello nos concentraremos en el concepto de enlace químico desde la perspectiva de los dos enfoques a través de los cuales la ecuación de Schrödinger se aplica a los sistemas químicos moleculares: la teoría del enlace de valencia (EV) y la teoría del orbital molecular (OM). Sobre la base de la presentación de ambos enfoques y su comparación, señalaremos que, a pesar de su denominación tradicional, no pueden considerarse estrictamente como teorías científicas, sino que se ajustan mejor a la noción de modelo; en particular, son modelos que incorporan conceptos y leyes tanto del ámbito de la mecánica cuántica como del de la química estructural. Estas consideraciones nos permitirán argumentar que la química cuántica no posee un referente ontológico autónomo, sino que se trata de un ámbito científico cuya vigencia descansa sobre su éxito práctico en el cálculo y la predicción. Finalmente, indicaremos de qué modo los enfoques EV y OM del enlace químico abren una nueva perspectiva respecto de la noción misma de modelo en ciencias empíricas

In spite of being a well articulated proposal, the theory of quantum histories, in its different versions, suffers from certain difficulties that have been pointed out in the literature. Nevertheless, two facets of the proposal have not been sufficiently stressed. On the one hand, it is a non-collapse formalism that should be technically appropriate to supply descriptions based on quantum properties at different times. On the other hand, it intends to provide an interpretation of quantum mechanics that solves the traditional puzzles of the theory. In this article we spell out the main criticisms to TQH and classify them into two groups: theoretical and interpretive. Whereas the latter might be ignored if the TQH were considered as a quantum formalism with its minimum interpretation, the former seems to point toward technical difficulties that must be faced in a theoretically adequate proposal. Precisely with the purpose of solving these difficulties, we introduce a different perspective, called Formalism of Generalized Contexts or Formalism of Contextual Histories, which supplies a precise condition for consistently talking of quantum properties at different times without the theoretical shortcomings of the TQH.

The aim of the present paper is to analyze the problem of the relationship between chemistry and physics, by focusing on the widely discussed case of the atomic orbitals. We will begin by remembering the difference between the physical and the chemical interpretation of the concept of orbital. Then, we will refer to the claim made in 1999 that atomic orbitals have been directly imaged for the first time. On this basis, we will analyze the problem from a new approach, by comparing the concept of orbital used in physics with the concept of orbital used in chemistry. Such an analysis will allow us to argue for an ontological pluralism that admits the coexistence of different ontologies without priorities or metaphysical privileges. From this philosophical framework, the concepts of chemical orbital and physical orbital correspond to two different ontologies. As a consequence, chemical orbitals are real entities belonging to the ontology of molecular chemistry, and can be observed like any other entity not belonging to the quantum mechanical ontology. DOI:10.5007/1808-1711.2010v14n3p309

The aim of this paper is to introduce a new member of the family of the modal interpretations of quantum mechanics. In this modal-Hamiltonian interpretation, the Hamiltonian of the quantum system plays a decisive role in the property-ascription rule that selects the definite-valued observables whose possible values become actual. We show that this interpretation is effective for solving the measurement problem, both in its ideal and its non-ideal versions, and we argue for the physical relevance of the property-ascription rule by applying it to well-known physical situations. Moreover, we explain how this interpretation supplies a description of the elemental categories of the ontology referred to by the theory, where quantum systems turn out to be bundles of possible properties.

Perhaps the hottest topic in the philosophy of chemistry is that of the relationship between chemistry and physics. The problem finds one of its main manifestations in the debate about the nature of molecular structure, given by the spatial arrangement of the nuclei in a molecule. The traditional strategy to address the problem is to consider chemical cases that challenge the definition of molecular structure in quantum–mechanical terms. Instead of taking that top-down strategy, in this paper we face the problem of the reduction of molecular structure to quantum mechanics from a bottom-up perspective: our aim is to show how the theoretical peculiarities of quantum mechanics stand against the possibility of molecular structure, defined in terms of the spatial relations of the nuclei conceived as individual localized objects. We will argue that, according to the theory, quantum “particles” are not individuals that can be identified as different from others and that can be reidentified through time; therefore, they do not have the ontological stability necessary to maintain the relations that can lead to a spatially definite system with an identifiable shape. On the other hand, although quantum chemists use the resources supplied by quantum mechanics with successful results, this does no mean reduction: their “approximations” add certain assumptions that are not justified in the context of quantum mechanics or are even inconsistent with the very formal structure of the theory.

The interpretation of the concept of reduced state is a subtle issue that has relevant consequences when the task is the interpretation of quantum mechanics itself. The aim of this paper is to argue that reduced states are not the quantum states of subsystems in the same sense as quantum states are states of the whole composite system. After clearly stating the problem, our argument is developed in three stages. First, we consider the phenomenon of environment-induced decoherence as an example of the case in which the subsystems interact with each other; we show that decoherence does not solve the measurement problem precisely because the reduced state of the measuring apparatus is not its quantum state. Second, the non-interacting case is illustrated in the context of no-collapse interpretations, in which we show that certain well-known experimental results cannot be accounted for due to the fact that the reduced states of the measured system and the measuring apparatus are conceived as their quantum states. Finally, we prove that reduced states are a kind of coarse-grained states, and for this reason they cancel the correlations of the subsystem with other subsystems with which it interacts or is entangled

According to classical molecular chemistry, molecules have a structure, that is, they are sets of atoms with a definite arrangements in space and held together by chemical bonds. The concept of molecular structure is central to modern chemical thought given its impressive predictive power. It is also a very useful concept in chemistry education, due to its role in the rationalization and visualization of microscopic phenomena. However, such a concept seems to find no place in the ontology described by quantum mechanics, since it appeals to classical notions such as the position of the atomic nuclei or the individuality of electrons. Although this problem has attracted the attention of several authors, the discussion is far from settled. Some authors adopt an explicitly reductionist position and advocate to reconstruct the concept of molecular structure within the framework of the quantum theory. Others, although acknowledging the conceptual discontinuity between quantum mechanics and molecular chemistry, keep the hope of future reduction alive. From an explicitly non-reductionist position, on the contrary, others authors conceive molecular structure as an emergent phenomenon. The purpose of this article is to propose a different line of argumentation to address this problem. By contrast to reduction and emergence, the admission of a multiplicity of ontologies, not necessarily linked by hierarchical connections, cancels the need of finding a relation of dependence between the molecular level and the quantum level. This ontologically pluralist position can be applied to the issue of molecular structure, in order to argue that it is possible to admit the existence of structure in the ontology of molecular chemistry, in spite of the fact that it does not exist in the quantum world.

Although during the last decades the philosophy of chemistry has greatly extended its thematic scope, the main difficulties appear in the attempt to link the chemical description of atoms and molecules and the description supplied by quantum mechanics. The aim of this paper is to analyze how the difficulties that threaten the continuous conceptual link between molecular chemistry and quantum mechanics can be overcome or, at least, moderated from the perspective of BM. With this purpose, in “The quantum-mechanical challenges” section the foundational incompatibility between chemical and SQM descriptions will be briefly recalled. “Bohmian mechanics” section will be devoted to explain the main features of BM. In “Empirical equivalence and underdetermination” section, the consequences of the empirical equivalence between SQM and BM will be discussed. Finally, in the Conclusion, we will stress the scope of the obtained conclusions and the philosophical difficulties that still remain even after adopting BM for foundational purposes.

According to Zurek, decoherence is a process resulting from the interaction between a quantum system and its environment; this process singles out a preferred set of states, usually called “pointer basis”, that determines which observables will receive definite values. This means that decoherence leads to a sort of selection which precludes all except a small subset of the states in the Hilbert space of the system from behaving in a classical manner: environment-induced-superselection (einselection) is a consequence of the process of decoherence. The aim of this paper is to present a new approach to decoherence, different from the mainstream approach of Zurek and his collaborators. We will argue that this approach offers conceptual advantages over the traditional one when problems of foundations are considered; in particular, from the new perspective, decoherence in closed quantum systems becomes possible and the preferred basis acquires a well founded definition.

In a recent article entitled “The problem of molecular structure just is the measurement problem”, Alexander Franklin and Vanessa Seifert argue that insofar as the quantum measurement problem is solved, the problems of molecular structure are resolved as well. The purpose of the present article is to show that such a claim is too optimistic. Although the solution of the quantum measurement problem is relevant to how the problem of molecular structure is faced, such a solution is not sufficient to account for the structure of molecules as understood in the field of chemistry.

Two recent papers appeared in FOOP disagree regarding the role played by decoherence in quantum physics. On the one hand, Elise Crull considers that decoherence, by itself, solves many conceptual problems in quantum physics, with no need of interpretative considerations. On the other hand, Antonio Vassallo and Michael Esfeld reply by correctly claiming that, although decoherence is a powerful tool to deal with conceptual problems, it does not dispense us from interpreting the formalism. In this brief note we want to contribute to the debate with further considerations from another viewpoint. In this work we show that the discussions "decoherence versus interpretation" revolve around whether the theory of decoherence requires interpretive considerations to solve the measurement problem. In general, those discussions take the theory of decoherence for granted, as if it would not involve any difficulty. Therefore, they commonly focus on the "interpretation" wing: even in the case that the open system decoheres in a given basis, the whole closed system is still in a superposition and, thus, without an adequate interpretation, it cannot be said that the observables defined by that basis behave classically. Here we have focused on the "decoherence" wing: given the conceptual challenges that the theory must face and the alternative approaches to the orthodox view, the understanding of the very phenomenon of decoherence still requires a great deal of interpretive work.

According to Zurek, decoherence is a process resulting from the interaction between a quantum system and its environment; this process singles out a preferred set of states, usually called “pointer basis”, that determines which observables will receive definite values. This means that decoherence leads to a sort of selection which precludes all except a small subset of the states in the Hilbert space of the system from behaving in a classical manner: environment-induced-superselection—einselection —is a consequence of the process of decoherence. The aim of this paper is to present a new approach to decoherence, different from the mainstream approach of Zurek and his collaborators. We will argue that this approach offers conceptual advantages over the traditional one when problems of foundations are considered; in particular, from the new perspective, decoherence in closed quantum systems becomes possible and the preferred basis acquires a well founded definition

By moving away from the traditional reductionist reading of the quantum theory of atoms in molecules, in this paper we analyze the role played by QTAIM in the relationship between molecular chemistry and quantum mechanics from an emergentist perspective. In particular, we show that such a relationship involves two steps: an intra-domain emergence and an inter-domain emergence. Intra-domain emergence, internal to quantum mechanics, results from the fact that the electron density, from which all the other QTAIM’s concepts are defined, arises from the wavefunction as a coarse-grained magnitude. Inter-domain emergence involves an analogical link, a mapping, between QTAIM’s entities, such as topological atoms and bond paths, and the entities that populate the molecular-chemistry domain, such as chemical atoms and chemical bonds.

In April 2016, Daniela Frauchiger and Renato Renner published an article online in which they introduce a Gedankenexperiment that led them to conclude that single-world interpretations of quantum theory cannot be self-consistent. In a new version of the paper, published in September 2018, the authors moderate their original claim by concluding that quantum theory cannot be extrapolated to complex systems, at least not in a straightforward manner. The purpose of this short article is to clarify the core of the F-R argument, in order to show how the contradiction is obtained. On the basis of this clarification, we argue that the result of the F-R argument has been overestimated and should be reconsidered from a more cautious perspective.

El objetivo del presente trabajo consiste en analizar las diferencias entre los enfoques de Boltzmann y de Gibbs respecto del problema de la irreversibilidad. Dicho análisis nos permitirá poner de manifiesto que, en las discusiones acerca de las condiciones necesarias para la irreversibilidad, no suele advertirse que la diferencia central entre los dos enfoques consiste en la utilización de diferentes conceptos de equilibrio y, por tanto, de irreversibilidad. Finalmente se argumentará que, si bien inicialmente ambos enfoques parecen por completo irreconciliables, existen condiciones físicas definidas bajo las cuales los resultados que proporcionan ambos marcos teóricos se aproximan lo suficiente como para ser considerados igualmente admisibles desde el punto de vista de la práctica de la física. /// The aim of this paper is to analyze the differences between the approaches of Boltzmann and Gibbs with respect to the problem of irreversibility. This analysis will allow us to show that, in the discussion about the necessary conditions for irreversibility, it goes often unnoticed that the main difference between the two approaches is the use of different concepts of equilibrium and, as a consequence, of irreversibility. Finally, we will argue that, although in principie both approaches seem completely irreconcilable, there are definite physical conditions under which the results provided by both theoretical frameworks are similar enough to be considered equally admissible for all practical purposes.

In the literature on the interpretation of quantum mechanics, not many works attempt to adopt a proactive perspective aimed at seeing how different interpretations can enrich each other through a productive dialogue. In particular, few proposals have been devised to show that different approaches can be clarified by comparing them, and can even complement each other, improving or leading to a more fertile overall approach. The purpose of this paper is framed within this perspective of complementation and mutual enrichment. In particular, the Relational Quantum Mechanics and the Modal-Hamiltonian Interpretation are compared, highlighting their differences and points of contact. The final purpose is to show that, in spite of their disagreements, they are not contradictory but, on the contrary, they can be made compatible from an overarching perspective and can even complement each other in a fruitful way.

Currently, there are almost as many conceptions of emergence as authors who address the issue. Most literature on the matter focuses either on discussing, evaluating and comparing particular contributions or accounts of emergence, or on assessing a particular case study. Our aim in this paper is rather different. We here set out to introduce a distinction that has not been sufficiently taken into account in previous discussions on this topic: the distinction between inter-domain emergence—a relation between items belonging to different ontic domains—and intra-domain emergence—a relation between items belonging to a same ontic domain. Our final purpose is not to assume and defend a definite stance on emergence, but to stress the relevance of such distinction when attempting to argue for or against emergence, in the first place. We will also address the connections between emergence so distinguished and more general philosophical perspectives, suggesting where would reductionists and pluralists stand with respect to intra- and inter-domain emergence.

In the present paper we address the problem of optical isomerism embodied in the socalled “Hund’s paradox”, which points to the difficulty to account for chirality by means of quantum mechanics. In particular, we explain the answer to the problem proposed by the theory of decoherence. The purpose of this article is to challenge this answer on the basis of a conceptual analysis of the phenomenon of decoherence, that reveals the limitations of the theory of decoherence to solve the difficulties posed by optical isomerism and, in general, by quantum measurement.