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"Physical theory"
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Joule’s Experiment as an Event Triggering a Formalization of a Baconian Science Till Up to an Alternative Theory to Newton’s One
A re-visitation of Joule’s experiment motivates a critical analysis of thermodynamic notions: heat, total energy, first principle, organization of a scientific theory, its relationships with logic and mathematics. A rational re-construction of thermodynamics is suggested according to the model of a problem-based organization, that Sadi Carnot applied to his formulation. The new formulation accomplishes the long time theoretical process started by Joule’s experiment within physicists community's collective mind, i.e. the process of exiting out Baconian science for suggesting a first theory out Newton’s paradigm, and eventually for introducing a pluralism of incompatible physical theories.
Journal Article
The Nature of Theory in Information Systems
The aim of this research essay is to examine the structural nature of theory in Information Systems. Despite the importance of theory, questions relating to its form and structure are neglected in comparison with questions relating to epistemology. The essay addresses issues of causality, explanation, prediction, and generalization that underlie an understanding of theory. A taxonomy is proposed that classifies information systems theories with respect to the manner in which four central goals are addressed: analysis, explanation, prediction, and prescription. Five interrelated types of theory are distinguished: (1) theory for analyzing, (2) theory for explaining, (3) theory for predicting, (4) theory for explaining and predicting, and (5) theory for design and action. Examples illustrate the nature of each theory type. The applicability of the taxonomy is demonstrated by classifying a sample of journal articles. The paper contributes by showing that multiple views of theory exist and by exposing the assumptions underlying different viewpoints. In addition, it is suggested that the type of theory under development can influence the choice of an epistemological approach. Support is given for the legitimacy and value of each theory type. The building of integrated bodies of theory that encompass all theory types is advocated.
Journal Article
Existence of an information unit as a postulate of quantum theory
Does information play a significant role in the foundations of physics? Information is the abstraction that allows us to refer to the states of systems when we choose to ignore the systems themselves. This is only possible in very particular frameworks, like in classical or quantum theory, or more generally, whenever there exists an information unit such that the state of any system can be reversibly encoded in a sufficient number of such units. In this work, we show how the abstract formalism of quantum theory can be deduced solely from the existence of an information unit with suitable properties, together with two further natural assumptions: the continuity and reversibility of dynamics, and the possibility of characterizing the state of a composite system by local measurements. This constitutes a set of postulates for quantum theory with a simple and direct physical meaning, like the ones of special relativity or thermodynamics, and it articulates a strong connection between physics and information.
Journal Article
Uncertainty Principle Determines the Nonlocality of Quantum Mechanics
Two central concepts of quantum mechanics are Heisenberg's uncertainty principle and a subtle form of nonlocality that Einstein famously called \"spooky action at a distance.\" These two fundamental features have thus far been distinct concepts. We show that they are inextricably and quantitatively linked: Quantum mechanics cannot be more nonlocal with measurements that respect the uncertainty principle. In fact, the link between uncertainty and nonlocality holds for all physical theories. More specifically, the degree of nonlocality of any theory is determined by two factors: the strength of the uncertainty principle and the strength of a property called \"steering,\" which determines which states can be prepared at one location given a measurement at another.
Journal Article
When does a physical system compute?
Computing is a high-level process of a physical system. Recent interest in non-standard computing systems, including quantum and biological computers, has brought this physical basis of computing to the forefront. There has been, however, no consensus on how to tell if a given physical system is acting as a computer or not; leading to confusion over novel computational devices, and even claims that every physical event is a computation. In this paper, we introduce a formal framework that can be used to determine whether a physical system is performing a computation. We demonstrate how the abstract computational level interacts with the physical device level, in comparison with the use of mathematical models in experimental science. This powerful formulation allows a precise description of experiments, technology, computation and simulation, giving our central conclusion: physical computing is the use of a physical system to predict the outcome of an abstract evolution. We give conditions for computing, illustrated using a range of non-standard computing scenarios. The framework also covers broader computing contexts, where there is no obvious human computer user. We introduce the notion of a 'computational entity', and its critical role in defining when computing is taking place in physical systems.
Journal Article
Are Newtonian Gravitation and Geometrized Newtonian Gravitation Theoretically Equivalent?
I argue that a criterion of theoretical equivalence due to Glymour (Noûs 11(3):227–251, 1977) does not capture an important sense in which two theories may be equivalent. I then motivate and state an alternative criterion that does capture the sense of equivalence I have in mind. The principal claim of the paper is that relative to this second criterion, the answer to the question posed in the title is \"yes\", at least on one natural understanding of Newtonian gravitation.
Journal Article
What is Shannon information?
Despite of its formal precision and its great many applications, Shannon's theory still offers an active terrain of debate when the interpretation of its main concepts is the task at issue. In this article we try to analyze certain points that still remain obscure or matter of discussion, and whose elucidation contribute to the assessment of the different interpretative proposals about the concept of information. In particular, we argue for a pluralist position, according to which the different views about information are no longer rival, but different interpretations of a single formal concept.
Journal Article
A glance beyond the quantum model
One of the most important problems in physics is to reconcile quantum mechanics with general relativity, and some authors have suggested that this may be realized at the expense of having to drop the quantum formalism in favour of a more general theory. Here, we propose a mechanism to make general claims on the microscopic structure of the Universe by postulating that any post-quantum theory should recover classical physics in the macroscopic limit. We use this mechanism to bound the strength of correlations between distant observers in any physical theory. Although several quantum limits are recovered, such as the set of two-point quantum correlators, our results suggest that there exist plausible microscopic theories of Nature that predict correlations impossible to reproduce in any quantum mechanical system.
Journal Article
Flexible Cooling Strategy for Hot-Rolled Steel Based on Physical Theories Coupled with Machine Learning
Based on the complex characteristics of nonlinearity, strong coupling, and multi-disturbance in hot-rolling steel production, developing a multi-objective optimization system for dynamic control of multi-scale process parameters is challenging. In this paper, novel solutions coupling physical mechanisms into the machine learning modeling are proposed, and their feasibility has been fully demonstrated by analyzing experimental verification and industrial trial production. By comparison with experimental data, the results show that the proposed model accurately describes the microstructure evolution during hot rolling and cooling under complex processing conditions. On this basis, the flexible cooling system is developed by multi-objective particle swarm optimization. Compared with the traditional purely data-driven optimization method, results show that the proposed model ensures that the optimization results meet the requirements of multiple property indicator collaborative optimization but also obtain the optimal comprehensive property and quality stability by controlling the cooling path. Finally, the established system applied to guide the industrial production of steel and the potential for matching optimum cooling parameters according to the fluctuation in steel composition and rolling parameters to achieve a compensatory effect is proved through metallographic observations of final microstructures under different cooling paths.
Journal Article