scholarly journals Entropy generation and momentum transfer in the superconductor–normal and normal–superconductor phase transformations and the consistency of the conventional theory of superconductivity

2018 ◽  
Vol 32 (13) ◽  
pp. 1850158 ◽  
Author(s):  
J. E. Hirsch
Keyword(s):  
Momentum Transfer ◽  
Entropy Generation ◽  
Meissner Effect ◽  
The Body ◽  
Alternative Theory ◽  
Conventional Theory ◽  
Laws Of Thermodynamics ◽  
Zero Entropy ◽  
First Order Phase ◽  
Theory Of Superconductivity

Since the discovery of the Meissner effect, the superconductor to normal (S–N) phase transition in the presence of a magnetic field is understood to be a first-order phase transformation that is reversible under ideal conditions and obeys the laws of thermodynamics. The reverse (N–S) transition is the Meissner effect. This implies in particular that the kinetic energy of the supercurrent is not dissipated as Joule heat in the process where the superconductor becomes normal and the supercurrent stops. In this paper, we analyze the entropy generation and the momentum transfer between the supercurrent and the body in the S–N transition and the N–S transition as described by the conventional theory of superconductivity. We find that it is not possible to explain the transition in a way that is consistent with the laws of thermodynamics unless the momentum transfer between the supercurrent and the body occurs with zero entropy generation, for which the conventional theory of superconductivity provides no mechanism. Instead, we point out that the alternative theory of hole superconductivity does not encounter such difficulties.

scholarly journals Thermodynamic inconsistency of the conventional theory of superconductivity

2020 ◽  
Vol 34 (19) ◽  
pp. 2050175
Author(s):  
J. E. Hirsch
Keyword(s):  
Magnetic Field ◽  
Alternative Theory ◽  
Type I ◽  
Conventional Theory ◽  
London Penetration Depth ◽  
Final State ◽  
Temperature Changes ◽  
Laws Of Thermodynamics ◽  
Thermodynamic Inconsistency ◽  
Theory Of Superconductivity

A type I superconductor expels a magnetic field from its interior to a surface layer of thickness [Formula: see text], the London penetration depth. [Formula: see text] is a function of temperature, becoming smaller as the temperature decreases. Here we analyze the process of cooling (or heating) a type I superconductor in a magnetic field, with the system remaining always in the superconducting state. The conventional theory predicts that Joule heat is generated in this process, the amount of which depends on the rate at which the temperature changes. Assuming the final state of the superconductor is independent of history, as the conventional theory assumes, we show that this process violates the first and second laws of thermodynamics. We conclude that the conventional theory of superconductivity is internally inconsistent. Instead, we suggest that the alternative theory of hole superconductivity may be able to resolve this problem.

scholarly journals The Law of Entropy Increase and the Meissner Effect

Entropy ◽  
2022 ◽  
Vol 24 (1) ◽  
pp. 83
Author(s):  
Alexey Nikulov
Keyword(s):  
Electric Current ◽  
Normal State ◽  
Irreversible Process ◽  
Meissner Effect ◽  
Joule Heat ◽  
Persistent Current ◽  
Conventional Theory ◽  
Entropy Increase ◽  
The Law ◽  
Theory Of Superconductivity

The law of entropy increase postulates the existence of irreversible processes in physics: the total entropy of an isolated system can increase, but cannot decrease. The annihilation of an electric current in normal metal with the generation of Joule heat because of a non-zero resistance is a well-known example of an irreversible process. The persistent current, an undamped electric current observed in a superconductor, annihilates after the transition into the normal state. Therefore, this transition was considered as an irreversible thermodynamic process before 1933. However, if this transition is irreversible, then the Meissner effect discovered in 1933 is experimental evidence of a process reverse to the irreversible process. Belief in the law of entropy increase forced physicists to change their understanding of the superconducting transition, which is considered a phase transition after 1933. This change has resulted to the internal inconsistency of the conventional theory of superconductivity, which is created within the framework of reversible thermodynamics, but predicts Joule heating. The persistent current annihilates after the transition into the normal state with the generation of Joule heat and reappears during the return to the superconducting state according to this theory and contrary to the law of entropy increase. The success of the conventional theory of superconductivity forces us to consider the validity of belief in the law of entropy increase.

scholarly journals Dynamic Equilibrium Equations in Unified Mechanics Theory

2021 ◽  
Vol 2 (1) ◽  
pp. 63-80
Author(s):  
Noushad Bin Jamal Bin Jamal M ◽  
Hsiao Wei Lee ◽  
Chebolu Lakshmana Rao ◽  
Cemal Basaran
Keyword(s):  
Energy Loss ◽  
Entropy Generation ◽  
Equilibrium Equation ◽  
Dynamic Equilibrium ◽  
Free Vibration Analysis ◽  
Newtonian Mechanics ◽  
Equilibrium Equations ◽  
Time Coordinate ◽  
Proposed Model ◽  
Laws Of Thermodynamics

Traditionally dynamic analysis is done using Newton’s universal laws of the equation of motion. According to the laws of Newtonian mechanics, the x, y, z, space-time coordinate system does not include a term for energy loss, an empirical damping term “C” is used in the dynamic equilibrium equation. Energy loss in any system is governed by the laws of thermodynamics. Unified Mechanics Theory (UMT) unifies the universal laws of motion of Newton and the laws of thermodynamics at ab-initio level. As a result, the energy loss [entropy generation] is automatically included in the laws of the Unified Mechanics Theory (UMT). Using unified mechanics theory, the dynamic equilibrium equation is derived and presented. One-dimensional free vibration analysis with frictional dissipation is used to compare the results of the proposed model with that of a Newtonian mechanics equation. For the proposed entropy generation equation in the system, the trend of predictions is comparable with the reported experimental results and Newtonian mechanics-based predictions.

scholarly journals Distribution of magnetic field around simply and multiply connected supraconductors

1936 ◽  
Vol 157 (890) ◽  
pp. 132-146 ◽  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Flux ◽  
Meissner Effect ◽  
The Body ◽  
Persistent Current ◽  
Closed Circuit ◽  
Multiply Connected ◽  
Constant Flux ◽  
Connected Body

The experiments to be described in this paper arose from a suggestion by M. von Laue that it would be of interest to examine more closely the behaviour of simply and multiply connected supraconducting bodies in an external magnetic field. If a closed circuit be taken wholly within a supraconducting body, sufficiently far from the surface, the magnetic flux through the circuit should be constant as long as no part of the body is subjected to a magnetic field greater than the critical field strength. For a simply connected body, if the spontaneous ejection of flux on cooling through the transition point, the so-called Meissner effect, is complete, the constant flux through any circuit should be zero. For a multiply connected body, it should be equal to the value immediately after the body became supraconducting. Only in the case of a multiply connected body, that is, a closed circuit, can there be a resultant current through any cross-section in the steady state. This may be taken as a definition of the current I in the circuit, the so-called persistent current. Let L be the self-inductance of the circuit, calculated for the supraconducting state on the assumption that the current flows entirely in a layer very close to the surface. Let ϕ be the calculated magnetic flux through the circuit due to external magnetic field, allowing for the distortion of the field by the presence of supraconducting material. Then, if it can be assumed that the maintenance of the constant flux through the closed circuit is due to a persistent current in the above sense, the law of constant flux can be written in the form LI + ϕ = ϕ 0 . (1)

Direct numerical calculation of acoustics: solution evaluation through energy analysis

1993 ◽  
Vol 254 ◽  
pp. 267-281 ◽  
Author(s):  
Kenneth S. Brentner
Keyword(s):  
Entropy Generation ◽  
Acoustic Waves ◽  
Fundamental Problem ◽  
Entropy Change ◽  
Inviscid Flow ◽  
The Body ◽  
Acoustic Energy ◽  
Cylinder Surface ◽  
Flow Solver ◽  
Temporal And Spatial Characteristics

The propagation of acoustic energy from a sound source to the far field is a fundamental problem of acoustics. In this paper the use of computational fluid dynamics (CFD) to directly calculate the acoustic field is investigated. The two-dimensional, compressible, inviscid flow about an accelerating circular cylinder is used as a model problem. The time evolution of the energy transfer from the cylinder surface to the fluid, as the cylinder is moved from rest to some non-negligible velocity, is shown. Energy is the quantity of interest in the calculations since various components of energy have physical meaning. By examining the temporal and spatial characteristics of the numerical solution, a distinction can be made between the propagating acoustic energy, the convecting energy associated with the entropy change in the fluid, and the energy following the body. In the calculations, entropy generation is due to a combination of physical mechanisms and numerical error. In the case of propagating acoustic waves, entropy generation seems to be a measure of numerical damping associated with the discrete flow solver.

scholarly journals Meissner Effect: History of Development and Novel Aspects

2021 ◽  
Author(s):  
Vladimir Kozhevnikov
Keyword(s):  
Fluid Model ◽  
Meissner Effect ◽  
Quantization Condition ◽  
Electromagnetic Properties ◽  
Equal Weight ◽  
Single Root ◽  
History Of ◽  
Zero Entropy ◽  
Standard Picture ◽  
Properties Of Superconductors

Abstract The discovery of the Meissner (Meissner–Ochsenfeld) effect in 1933 was an incontestable turning point in the history of superconductivity. First, it demonstrated that superconductivity is an unknown before equilibrium state of matter, thus allowing to use the power of thermodynamics for its study. This provided a justification for the two-fluid model of Gorter and Casimir, a seminal thermodynamic theory founded on a postulate of zero entropy of the superconducting (S) component of conduction electrons. Second, the Meissner effect demonstrated that, apart from zero electric resistivity, the S phase is also characterized by zero magnetic induction. The latter property is used as a basic postulate in the theory of F. and H. London, which underlies the understanding of electromagnetic properties of superconductors. Here the experimental and theoretical aspects of the Meissner effect are reviewed. The reader will see that, in spite of almost nine decades age, the London theory still contains questions, the answers to which can lead to a revision of the standard picture of the Meissner state (MS) and, if so, of other equilibrium superconducting states. An attempt is made to take a fresh look at electrodynamics of the MS and try to work out with the issues associated with this the most important state of all superconductors. It is shown that the concept of Cooper's pairing along with the Bohr–Sommerfeld quantization condition allows one to construct a semi-classical theoretical model consistently addressing properties of the MS and beyond, including non-equilibrium properties of superconductors caused by the total current. As follows from the model, the three “big zeros” of superconductivity (zero resistance, zero induction and zero entropy) have equal weight and grow from a single root: quantization of the angular momentum of paired electrons. The model predicts some yet unknown effects. If confirmed, they can help in studies of microscopic properties of all superconductors. Preliminary experimental results suggesting the need to revise the standard picture of the MS are presented.

scholarly journals COMPARISON OF TWO INTERPRETATIONS OF THE JOSEPHSON EFFECT

2010 ◽  
Vol 24 (30) ◽  
pp. 5847-5860
Author(s):  
I. M. YURIN
Keyword(s):  
Quantum Physics ◽  
Josephson Effect ◽  
Bcs Theory ◽  
Alternative Theory ◽  
Theory Of Superconductivity

This paper puts forward an interpretation of the Josephson effect based on the alternative theory of superconductivity (ATS). A comparison of the ATS- and BCS-based interpretations is provided. It is demonstrated that the ATS-based interpretation, unlike that based on the BCS theory, does not require a revision of fundamentals of quantum physics.

Performativity and the Intellectual Historian's Re-enactment of Written Works

2009 ◽  
Vol 3 (2) ◽  
pp. 167-186 ◽  
Author(s):  
Colin Tyler
Keyword(s):  
The Body ◽  
Alternative Theory ◽  
Family Resemblances

AbstractThis article develops and defends a performative conception of historical re-enactment as a fruitful method by which intellectual historians can interpret texts. Specifically, it argues that, in order to understand properly any given text, the intellectual historian should re-enact the performative activities of the writer of that text. The first section analyses one of the most influential and powerful theories of historical re-enactment, namely that found in the later writings of Robin George Collingwood. Drawing on Wittgenstein's theory of family resemblances, certain key insights are identified in Collingwood's theory. Crucially, certain limitations are also stressed. The second section argues that an alternative theory of re-enactment can be developed by drawing on Judith Butler's theory of "performativity". The interpretative implications of a writer's genre, mode of experience, presuppositions, deliberate inventiveness and unintended failures are highlighted. The particularized nature of texts is shown to problematize the writing of unilinear histories of written debates. The article concludes by summarizing briefly the key methodological implications of performative re-enactment as they have been identified in the body of the article.

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