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In this paper we argue that the formalisms for decoherence originally devised to deal just with closed or open systems can be subsumed under a general conceptual framework, in such a way that they cooperate in the understanding of the same physical phenomenon. This new perspective dissolves certain conceptual difficulties of the einselection program but, at the same time, shows that the openness of the quantum system is not the essential ingredient for decoherence. †To contact the authors, please write to: Mario Castagnino, CONICET-IAFE, Universidad Nacional de Buenos Aires, Casilla de Correos 67, Sucursal 28, 1428 Buenos Aires, Argentina; Roberto Laura, IFIR-Universidad Nacional de Rosario, Av. Pellegrini 250, 2000 Rosario, Argentina; Olimpia Lombardi, CONICET-Universidad Nacional de Buenos Aires, C. Larralde 3440, 6°D, 1430, Buenos Aires; e-mail: [email protected]

In the problem of the relationship between chemistry and physics, many authors take for granted the ontological reduction of the chemical world to the world of physics. The autonomy of chemistry is usually defended on the basis of the failure of epistemological reduction: not all chemical concepts and laws can be derived from the theoretical framework of physics. The main aim of this paper is to argue that this line of argumentation is not strong enough for eliminate the idea of a hierarchical dependence of chemistry with respect to physics. The rejection of the secondary position of chemistry and the defense of the legitimacy of the philosophy of chemistry require a radically different philosophical perspective that denies not only epistemological reduction but also ontological reduction. Only on the basis of a philosophically grounded ontological pluralism it is possible to accept the ontological autonomy of the chemical world and, with this, to reverse the traditional idea of the ‘superiority’ of physics in the context of natural sciences.

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.

Ilya Prigogine was not a systematic author: his ideas, covering a wide arch of areas, are dispersed in his many writings. In particular, his philosophical thought has to be reconstructed mainly on the basis of his works in collaboration with Isabelle Stengers: La Nouvelle Alliance ( 1979 ), Order out of Chaos ( 1984 ), and Entre le Temps et l’Éternité ( 1988 ). In this paper I undertake that reconstruction in order to argue that Prigogine’s position, when read in the light of Putnam’s internalist realism, can be characterized as an ontological pluralism. The main aim of this work is to show the striking parallelism between the philosophical views of Prigogine and Stengers and those of Hilary Putnam in Reason , Truth and History ( 1981 ). This task will lead me to critically review Prigogine’s general scientific program: the attempt to establish the foundations of objective irreversibility.

Traditional discussions about the arrow of time in general involve the concept of entropy. In the cosmological context, the direction past-to-future is usually related to the direction of the gradient of the entropy function of the universe. But the definition of the entropy of the universe is a very controversial matter. Moreover, thermodynamics is a phenomenological theory. Geometrical properties of space-time provide a more fundamental and less controversial way of defining an arrow of time for the universe as a whole. We will call the arrow defined only on the basis of the geometrical properties of space-time, independently of any entropic considerations, “the global arrow of time.” In this paper we will argue that: (i) if certain conditions are satisfied, it is possible to define a global arrow of time for the universe as a whole, and (ii) the standard models of contemporary cosmology satisfy these conditions

Given the impressive success of environment-induced decoherence, nowadays no interpretation of quantum mechanics can ignore its results. The modal-Hamiltonian interpretation has proved to be effective for solving several interpretative problems but, since its actualization rule applies to closed systems, it seems to stand at odds of EID. The purpose of this paper is to show that this is not the case: the states einselected by the interaction with the environment according to EID are the eigenvectors of an actual-valued observable belonging to the preferred context selected by the MHI.

In several previous papers we have argued for a global and non-entropic approach to the problem of the arrow of time, according to which the “arrow” is only a metaphorical way of expressing the geometrical time-asymmetry of the universe. We have also shown that, under definite conditions, this global time-asymmetry can be transferred to local contexts as an energy flow that points to the same temporal direction all over the spacetime. The aim of this paper is to complete the global and non-entropic program by showing that our approach is able to account for irreversible local phenomena, which have been traditionally considered as the physical origin of the arrow of time

The main aim of this work is to contribute tothe elucidation of the concept of informationby comparing three different views about thismatter: the view of Fred Dretske's semantictheory of information, the perspective adoptedby Peter Kosso in his interaction-informationaccount of scientific observation, and thesyntactic approach of Thomas Cover and JoyThomas. We will see that these views involvevery different concepts of information, eachone useful in its own field of application. This comparison will allow us to argue in favorof a terminological `cleansing': it is necessaryto make a terminological distinction among thedifferent concepts of information, in order toavoid conceptual confusions when the word`information' is used to elucidate relatedconcepts as knowledge, observation orentropy

The general question to be considered in this paper points to the nature of the world described by chemistry: what is macro-chemical ontology like? In particular, we want to identify the ontological categories that underlie chemical discourse and chemical practice. This is not an easy task, because modern Western metaphysics was strongly modeled by theoretical physics. For this reason, we attempt to answer our question by contrasting macro-chemical ontology with the mainstream ontology of physics and of traditional metaphysics. In particular, we introduce the distinction between stuff-ontology, proper of chemistry, and individual-ontology, proper of physics. These two ontologies differ from each other in the basic categories of their own structures. On this basis, we characterize individual-ontology in such a way that the features of stuff-ontology will arise by contrast with it

In this paper we argue that the emergence of the classical world from the underlying quantum reality involves two elements: self-induced decoherence and macroscopicity. Self-induced decoherence does not require the openness of the system and its interaction with the environment: a single closed system can decohere when its Hamiltonian has continuous spectrum. We show that, if the system is macroscopic enough, after self-induced decoherence it can be described as an ensemble of classical distributions weighted by their corresponding probabilities. We also argue that classicality is an emergent property that arises when the behavior of the system is described from an observational perspective.

In this paper we will address the problem of the existence of orbitals by analyzing the relationship between molecular chemistry and quantum mechanics. In particular, we will consider the concept of orbital in the light of the arguments that deny its referring character. On this basis, we will conclude that the claim that orbitals do not exist relies on a metaphysical reductionism which, if consistently sustained, would lead to consequences clashing with the effective practice of science in its different branches.

Since the nineteenth century, the problem of the arrow of time has been traditionally analyzed in terms of entropy by relating the direction past-to-future to the gradient of the entropy function of the universe. In this paper, we reject this traditional perspective and argue for a global and non-entropic approach to the problem, according to which the arrow of time can be defined in terms of the geometrical properties of spacetime. In particular, we show how the global non-entropic arrow can be transferred to the local level, where it takes the form of a non-spacelike local energy flow that provides the criterion for breaking the symmetry resulting from time-reversal invariant local laws.

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.

According to the environment-induced approach to decoherence, the split of the Universe into the degrees of freedom which are of direct interest to the observer and the remaining degrees of freedom is absolutely essential for decoherence. However, the EID approach offers no general criterion for deciding where to place the “cut” between system and environment: the environment may be “external” or “internal”. The main purpose of this paper is to argue that decoherence is a relative phenomenon, better understood from a closed-system perspective according to which the split of a closed quantum system into an open subsystem and its environment is just a way of selecting a particular space of relevant observables of the whole closed system. In order to support this claim, we shall consider the results obtained in a natural generalization of the simple spin-bath model usually studied in the literature. Our main thesis will lead us to two corollaries. First, the problem of identifying the system that decoheres is actually a pseudo-problem, which vanishes as soon as one acknowledges the relative nature of decoherence. Second, the usually supposed link between decoherence and energy dissipation is misguided. As previously pointed out, energy dissipation and decoherence are different phenomena, and we shall argue for this difference on the basis of the relative nature of decoherence

Scientific cosmology is an empirical discipline whose objects of study are the large-scale properties of the universe. In this context, it is usual to call the direction of the expansion of the universe the "cosmological arrow of time". However, there is no reason for privileging the ‘radius’ of the universe for defining the arrow of time over other geometrical properties of the space-time. Traditional discussions about the arrow of time in general involve the concept of entropy. In the cosmological context, the direction past-to-future is usually related to the direction of the gradient of the entropy function of the universe. But entropy is a thermodynamic magnitude that is typically associated with subsystems of the universe: the entropy of the universe as a whole is a very controversial matter. Moreover, thermodynamics is a phenomenological theory. Geometrical properties of space-time provide a more fundamental and less controversial way of defining an arrow of time for the universe as a whole. We will call the arrow defined only on the basis of the geometrical properties of space-time, independently of any entropic considerations, the "cosmological arrow of time". In this paper we will argue that: (i) it is possible to define a cosmological arrow of time for the universe as a whole, if certain conditions are satisfied, and (ii) the standard models of contemporary cosmology satisfy these conditions.

The aim of this paper is to consider in what sense the modal-Hamiltonian interpretation of quantum mechanics satisfies the physical constraints imposed by the Galilean group. In particular, we show that the only apparent conflict, which follows from boost-transformations, can be overcome when the definition of quantum systems and subsystems is taken into account. On this basis, we apply the interpretation to different well-known models, in order to obtain concrete examples of the previous conceptual conclusions. Finally, we consider the role played by the Casimir operators of the Galilean group in the interpretation

The many-faced relationship between chemistry and physics is one of the most discussed topics in the philosophy of chemistry. In his recent book Reducing Chemistry to Physics. Limits, Models, Consequences, Hinne Hettema conceives this relationship as a reduction link, and devotes his work to defend this position on the basis of a “naturalized” concept of reduction. In the present paper I critically review three kinds of issues stemming from Hettema’s argumentation: philosophical, scientific and methodological

The aim of this paper is to analyze time-asymmetric quantum mechanics with respect to the problems of irreversibility and of time's arrow. We begin with arguing that both problems are conceptually different. Then, we show that, contrary to a common opinion, the theory's ability to describe irreversible quantum processes is not a consequence of the semigroup evolution laws expressing the non-time-reversal invariance of the theory. Finally, we argue that time-asymmetric quantum mechanics, either in Prigogine's version or in Bohm's version, does not solve the problem of the arrow of time because it does not supply a substantial and theoretically founded criterion for distinguishing between the two directions of time.

El propósito del presente artículo es evaluar en qué sentido y bajo qué condiciones la ergodicidad es relevante para explicar el éxito de la mecánica estadística. Se objeta la positión de quienes sostienen que la ergodicidad es irrelevante para tal explicatión, y se señala que las propiedades ergódicas desempeñan diferentes papeles en la mecánica estadística del equilibrio y en la descriptión de la evolución hacia el equilibrio: es posible prescindir de la ergodicidad en el primer caso pero no en el segundo. Sobre esta base, se reformularán las definiciones de ergodicidad y mezcla, relativizándolas a la macrovariable particular cuya evolución irreversible se desea describir. Finalmente, se enfatiza la importancia de tomar en cuenta la elaboratión de modelos para evaluar la utilizatión de los métodos de Gibbs. /// The aim of this paper is to consider in what sense and under what conditions ergodicity is relevant for explaining the success of Statistical Mechanics. We argue against those who claim that ergodicity is irrelevant to this explanation, by noting that ergodic properties play different roles in equilibrium Statistical Mechanics and in the description of the approach to equilibrium: it is possible to do without it in the first case but not in the second one. On this basis, we reformulate the definitions of ergodicity and mixing, relativizing them to the particular macrovariable whose irreversible evolution is to be described. Finally, we stress the relevance of taking into account model-construction for evaluating the use of Gibbs' methods.

Christopher Timpson proposes a deflationary view about information, according to which the term ‘information’ is an abstract noun and, as a consequence, information is not part of the material contents of the world. The main purpose of the present article consists in supplying a critical analysis of this proposal, which will lead us to conclude that information is an item even more abstract than what Timpson claims. From this view, we embrace a pluralist stance that recognizes the legitimacy of different interpretations of the concept of information.

The aim of this paper is to analyze the concepts of time-reversal invariance and irreversibility in the so-called 'time-asymmetric quantum mechanics'. We begin with pointing out the difference between these two concepts. On this basis, we show that irreversibility is not as tightly linked to the semigroup evolution laws of the theory -which lead to its non time-reversal invariance- as usually suggested. In turn, we argue that the irreversible evolutions described by the theory are coarse-grained processes.

RESUMEN: El propósito del presente trabajo consiste en analizar los vínculos entre la interpretación modal-hamiltoniana de la mecánica cuántica y las transformaciones de Galileo, a fin de poner de manifiesto que el grupo de tales transformaciones permite reformular la regla de actualización de un modo más básico desde un punto de vista teórico, aplicable a otras teorías cuánticas. Además se argumentará que, bajo esta nueva forma, la regla de actualización manifiesta explícitamente su invariancia frente al grupo de Galileo.ABSTRACT: The purpose of the present work consists in analyzing the links between the modal-Hamiltonian interpretation of quantummechanics and the Galilean transformations, with the aim of showing that the group of such transformations allows to reformulate the actualization rule in a theoretically more basic way, applicable to other quantum theories. Moreover, it will be argued that, under this new form, the actualization rule explicitly manifests its invariance with respect to the Galilean group.

En su libro "Time's Arrow and Archimedes' Point", Huw Price critica los argumentos de algunos cosmólogos contemporáneos acerca del origen cosmológico de la flecha del tiempo, quienes supuestamente no logran adoptar un punto de vista atemporal. En este artículo se analizan las criticas de Price a la propuesta de Stephen Hawking, argumentando que sus conclusiones se basan en supuestos cuestionables desde un punto de vista científico. Esta tarea abre el camino hacía un enfoque global no-entrópico de la flecha del tiempo, que permite establecer un nuevo diálogo con la propuesta de Price

The problem of the reduction of chemistry to physics has been traditionally addressed in terms of classical structural chemistry and standard quantum mechanics. In this work, we will study the problem from the perspective of the Quantum Theory of Atoms in Molecules, proposed by Richard Bader in the nineties. The purpose of this article is to unveil the role of QTAIM in the inter-theoretical relations between chemistry and physics. We argue that, although the QTAIM solves two relevant obstacles to reduction by providing a rigorous definition of chemical bond and of atoms in a molecule, it appeals to concepts that are unacceptable in the quantum–mechanical context. Therefore, the QTAIM fails to provide the desired reduction. On the other hand, we will show that the QTAIM is more similar to Bohmian mechanics and that the basic elements of both theories are closely related.