Entropy

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163 KiB

Open AccessArticle

Statistical Vibroacoustics and Entropy Concept

by Alain Le Bot, Antonio Carcaterra and Denis Mazuyer

Entropy 2010, 12(12), 2418-2435; https://doi.org/10.3390/e12122418 - 13 Dec 2010

Cited by 25 | Viewed by 7815

Abstract

Statistical vibroacoustics, also called statistical energy analysis (SEA) in the field of engineering, is born from the application of statistical physics concepts to the study of random vibration in mechanical and acoustical systems. This article is a discussion on the thermodynamic foundation for [...] Read more.

Statistical vibroacoustics, also called statistical energy analysis (SEA) in the field of engineering, is born from the application of statistical physics concepts to the study of random vibration in mechanical and acoustical systems. This article is a discussion on the thermodynamic foundation for that approach with particular emphasis devoted to the meaning of entropy, a concept missing in SEA. The theory focuses on vibration confined to the audio frequency range. In this frequency band, heat is defined as random vibration that is disordered vibration and temperature is the vibration energy per mode. Always in this frequency band, the concept of entropy is introduced and its meaning and role in vibroacoustics are enlightened, together with the related evolutionary equation. It is shown that statistical vibroacoustics is non-equilibrium thermodynamics applied to the audio range. Full article

(This article belongs to the Special Issue Nonequilibrium Thermodynamics)

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281 KiB

Open AccessArticle

Cultural Naturalism

by Arto Annila and Stanley Salthe

Entropy 2010, 12(6), 1325-1343; https://doi.org/10.3390/e12061325 - 26 May 2010

Cited by 24 | Viewed by 10290

Abstract

Culture can be viewed as the means by which a society can live in its surroundings by acquiring and consuming free energy. This naturalistic notion assumes that everything can be valued in terms of energy, hence also social changes can be described as [...] Read more.

Culture can be viewed as the means by which a society can live in its surroundings by acquiring and consuming free energy. This naturalistic notion assumes that everything can be valued in terms of energy, hence also social changes can be described as natural processes that are influenced by the 2nd Law of Thermodynamics. This universal law, when formulated as an equation of motion, reveals that societies emerge, evolve and eventually extinguish after tapping, exploiting and finally depleting their resources, which we can say are ultimately valued in energetic terms. The analysis reveals that trajectories of societies are, however, inherently non-integrable, i.e., unpredictable in detail because free energy as the driving force, being finite, is inseparable from the flows of energy. Nonetheless, the universal tendency to diminish energy differences within a system and with respect to its surroundings in the least possible time gives rise to highly economical but seemingly immaterial means of energy transduction that associate with cultural codes, habits, traditions, taboos and values. Moreover, cultural naturalism clarifies that identities develop and mature in interactions, and that class structure results from the quest for maximum entropy partition. While social changes in complex societies are inherently intractable, the profound principle allows us to recognize universal tendencies in diverse cultural characteristics, and to rationalize prospects for the future. Full article

(This article belongs to the Special Issue Nonequilibrium Thermodynamics)

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1242 KiB

Open AccessArticle

Emergence of Animals from Heat Engines – Part 1. Before the Snowball Earths

by Anthonie W. J. Muller

Entropy 2009, 11(3), 463-512; https://doi.org/10.3390/e11030463 - 18 Sep 2009

Cited by 4 | Viewed by 12614

Abstract

The origin of life has previously been modeled by biological heat engines driven by thermal cycling, caused by suspension in convecting water. Here more complex heat engines are invoked to explain the origin of animals in the thermal gradient above a submarine hydrothermal [...] Read more.

The origin of life has previously been modeled by biological heat engines driven by thermal cycling, caused by suspension in convecting water. Here more complex heat engines are invoked to explain the origin of animals in the thermal gradient above a submarine hydrothermal vent. Thermal cycling by a filamentous protein ‘thermotether’ was the result of a temperature-gradient induced relaxation oscillation not impeded by the low Reynolds number of a small scale. During evolution a ‘flagellar proton pump’ emerged that resembled Feynman’s ratchet and that turned into today’s bacterial flagellar motor. An emerged ‘flagellar computer’ functioning as Turing machine implemented chemotaxis. Full article

(This article belongs to the Special Issue Nonequilibrium Thermodynamics)

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Review

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553 KiB

Open AccessReview

Thermodynamics and Fluctuations Far From Equilibrium

by John Ross and Alejandro Fernández Villaverde

Entropy 2010, 12(10), 2199-2243; https://doi.org/10.3390/e12102199 - 21 Oct 2010

Cited by 17 | Viewed by 9484

Abstract

We review a coherent mesoscopic presentation of thermodynamics and fluctuations far from and near equilibrium, applicable to chemical reactions, energy transfer and transport processes, and electrochemical systems. Both uniform and spatially dependent systems are considered. The focus is on processes leading to and [...] Read more.

We review a coherent mesoscopic presentation of thermodynamics and fluctuations far from and near equilibrium, applicable to chemical reactions, energy transfer and transport processes, and electrochemical systems. Both uniform and spatially dependent systems are considered. The focus is on processes leading to and in non‑equilibrium stationary states; on systems with multiple stationary states; and on issues of relative stability of such states. We establish thermodynamic state functions, dependent on the irreversible processes, with simple physical interpretations that yield the work available from these processes and the fluctuations. A variety of experiments are cited that substantiate the theory. The following topics are included: one-variable systems, linear and nonlinear; connection of thermodynamic theory with stochastic theory; multivariable systems; relative stability of different phases; coupled transport processes; experimental determination of thermodynamic and stochastic potentials; dissipation in irreversible processes and nonexistence of extremum theorems; efficiency of oscillatory reactions, including biochemical systems; and fluctuation-dissipation relations. Full article

(This article belongs to the Special Issue Nonequilibrium Thermodynamics)

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1273 KiB

Open AccessReview

Sub-Quantum Thermodynamics as a Basis of Emergent Quantum Mechanics

by Gerhard Grössing

Entropy 2010, 12(9), 1975-2044; https://doi.org/10.3390/e12091975 - 10 Sep 2010

Cited by 25 | Viewed by 10145

Abstract

This review presents results obtained from our group’s approach to model quantum mechanics with the aid of nonequilibrium thermodynamics. As has been shown, the exact Schrödinger equation can be derived by assuming that a particle of energy is actually a dissipative system maintained [...] Read more.

This review presents results obtained from our group’s approach to model quantum mechanics with the aid of nonequilibrium thermodynamics. As has been shown, the exact Schrödinger equation can be derived by assuming that a particle of energy is actually a dissipative system maintained in a nonequilibrium steady state by a constant throughput of energy (heat flow). Here, also other typical quantum mechanical features are discussed and shown to be completely understandable within our approach, i.e., on the basis of the assumed sub-quantum thermodynamics. In particular, Planck’s relation for the energy of a particle, the Heisenberg uncertainty relations, the quantum mechanical superposition principle and Born’s rule, or the “dispersion of the Gaussian wave packet”, a.o., are all explained on the basis of purely classical physics. Full article

(This article belongs to the Special Issue Nonequilibrium Thermodynamics)

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