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Entropy, Volume 6, Issue 1 (March 2004) – 20 articles , Pages 1-232

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254 KiB  
Article
Markov Property and Operads
by Rémi Léandre
Entropy 2004, 6(1), 180-215; https://doi.org/10.3390/e6010180 - 31 Mar 2004
Cited by 5 | Viewed by 5726
Abstract
We define heat kernel measure on punctured spheres. The random field which is got by this procedure is not Gaussian. We define a stochastic line bundle on the loop space, such that the punctured sphere corresponds to a generalized parallel transport on this [...] Read more.
We define heat kernel measure on punctured spheres. The random field which is got by this procedure is not Gaussian. We define a stochastic line bundle on the loop space, such that the punctured sphere corresponds to a generalized parallel transport on this line bundle. Markov property along the sewing loops corresponds to an operadic structure of the stochastic W.Z.N.W. model. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
39 KiB  
Editorial
Special Issue on Quantum Limits to the Second Law of Thermodynamics
by Alexey V. Nikulov and Daniel P. Sheehan
Entropy 2004, 6(1), 1-10; https://doi.org/10.3390/e6010001 - 31 Mar 2004
Cited by 17 | Viewed by 6364
Abstract
Over fifty years ago Arthur Eddington wrote [1]: “The second law of thermodynamics holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's [...] Read more.
Over fifty years ago Arthur Eddington wrote [1]: “The second law of thermodynamics holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations – then so much the worse for Maxwell's equations. If it is found to be contradicted by observation, well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation”.[...] Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
145 KiB  
Article
A Collision Between Dynamics and Thermodynamics
by Craig Callender
Entropy 2004, 6(1), 11-20; https://doi.org/10.3390/e6010011 - 30 Mar 2004
Cited by 10 | Viewed by 6216
Abstract
Philosophers of science have found the literature surrounding Maxwell's demon deeply problematic. This paper explains why, summarizing various philosophical complaints and adding to them. The first part of the paper critically evaluates attempts to exorcise Maxwell's demon; the second part raises foundational questions [...] Read more.
Philosophers of science have found the literature surrounding Maxwell's demon deeply problematic. This paper explains why, summarizing various philosophical complaints and adding to them. The first part of the paper critically evaluates attempts to exorcise Maxwell's demon; the second part raises foundational questions about some of the putative demons that are being summoned. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
99 KiB  
Article
A Modified Szilard's Engine: Measurement, Information, and Maxwell's Demon
by Michael Devereux
Entropy 2004, 6(1), 102-115; https://doi.org/10.3390/e6010102 - 23 Mar 2004
Cited by 1 | Viewed by 7426
Abstract
Using an isolated measurement process, I've calculated the effect measurement has on entropy for the multi-cylinder Szilard engine. This calculation shows that the system of cylinders possesses an entropy associated with cylinder total energy states, and that it records information transferred at measurement. [...] Read more.
Using an isolated measurement process, I've calculated the effect measurement has on entropy for the multi-cylinder Szilard engine. This calculation shows that the system of cylinders possesses an entropy associated with cylinder total energy states, and that it records information transferred at measurement. Contrary to other's results, I've found that the apparatus loses entropy due to measurement. The Second Law of Thermodynamics may be preserved if Maxwell's demon gains entropy moving the engine partition. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>A) The classical Szilard engine contains a single gas molecule in a cylinder. The partition is inserted and the demon then determines which half of the cylinder confines the molecule. If the partition is replaced by a piston, the gas may expand, doing work. B) A quantum mechanical model of the Szilard engine. The infinite square well may be divided with a partition. Measurement of the gas location then limits the molecule to one side of the cylinder.</p>
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946 KiB  
Article
Delocalization and Sensitivity of Quantum Wavepacket in Coherently Perturbed Kicked Anderson Model
by Hiroaki Yamada
Entropy 2004, 6(1), 133-152; https://doi.org/10.3390/e6010133 - 21 Mar 2004
Viewed by 4200
Abstract
We consider quantum diffusion of the initially localized wavepacket in one-dimensional kicked disordered system with classical coherent perturbation. The wavepacket localizes in the unperturbed kicked Anderson model. However, the wavepacket get delocalized even by coupling with monochromatic perturbation. We call the state "dynamically [...] Read more.
We consider quantum diffusion of the initially localized wavepacket in one-dimensional kicked disordered system with classical coherent perturbation. The wavepacket localizes in the unperturbed kicked Anderson model. However, the wavepacket get delocalized even by coupling with monochromatic perturbation. We call the state "dynamically delocalized state". It is numerically shown that the delocalized wavepacket spread obeying diffusion law, and the perturbation strength dependence of the diffusion rate is given. The sensitivity of the delocalized state is also shown by the time-reversal experiment after random change in phase of the wavepacket. Moreover, it is found that the diffusion strongly depend on the initial phase of the perturbation. We discuss a relation between the "classicalization" of the quantum wave packet and the time-dependence of the initial phase dependence. The complex structure of the initial phase dependence is related to the entropy production in the quantum system. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
28 KiB  
Article
Smoluchowski's Trapdoor
by Lyndsay G.M. Gordon
Entropy 2004, 6(1), 96-101; https://doi.org/10.3390/e6010096 - 21 Mar 2004
Cited by 4 | Viewed by 6909
Abstract
A mechanism of a gated pore in a membrane is described. Fluxes of gas molecules pass through the pore and produce a pressure gradient in a process that challenges the second law. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>A magnified view of the membrane pore and the gating particle or trapdoor shown in the closed position.. The membrane contains a large number of gated pores oriented in the same direction. The resident times in open and closed positions are long in comparison with transition times.</p>
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<p>The potential energy profile of the trapdoor between its open and closed states. At the extremes of the profile the potential energy rises steeply above the activation energy barrier. The standard free energy (potential energy) between states is shown.</p>
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38 KiB  
Article
A Maxwellian Valve based on centrifugal forces
by Lyndsay G.M. Gordon
Entropy 2004, 6(1), 87-95; https://doi.org/10.3390/e6010087 - 21 Mar 2004
Cited by 6 | Viewed by 5094
Abstract
A mechanism is described which can create a chemical potential gradient from a single heat reservoir. The mechanism is equivalent to a Maxwellian valve. Heat supplies the energy through thermal fluctuations to form the gradient contrary to the second law. A quantitative analysis [...] Read more.
A mechanism is described which can create a chemical potential gradient from a single heat reservoir. The mechanism is equivalent to a Maxwellian valve. Heat supplies the energy through thermal fluctuations to form the gradient contrary to the second law. A quantitative analysis of the system is given. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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Figure 1
<p>Four states of an enzyme are shown. Two of the states, P and Q, are conformers of the enzyme and the two other states are the same conformers SP and SQ respectively on which a solute molecule of S is adsorbed. The enzyme is embedded in a membrane with its x-axis perpendicular to the membrane. The adsorption sites on P and SP lie on one side of the membrane and those of Q and SQ lie on the other. The sites, occupied or empty, pass through the membrane intact during conformational changes. Q has a different moment of inertia from the other states.</p>
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<p>Apore in a membrane which facilitates cation transport. The pore extends into solution ‘A’ and cations are required to exit and enter from ‘A’ via an orifice in the side of the pore. The pore rotates by Brownian motion.</p>
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74 KiB  
Article
The Decrease in Entropy via Fluctuations
by Lyndsay G.M. Gordon
Entropy 2004, 6(1), 38-49; https://doi.org/10.3390/e6010038 - 21 Mar 2004
Cited by 10 | Viewed by 5836
Abstract
Classical and quantum aspects of fluctuations are reviewed in a discussion on the universality of the second law. Consideration is given to the need of information and the requirement of a ratchet and pawl-type mechanism for the utilization of energy from fluctuations. Some [...] Read more.
Classical and quantum aspects of fluctuations are reviewed in a discussion on the universality of the second law. Consideration is given to the need of information and the requirement of a ratchet and pawl-type mechanism for the utilization of energy from fluctuations. Some aspects of the quantum theory of the Copenhagen school are compared to those of Bohm within the discussion. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>The device of Szilard. (A) The load has been coupled to the piston by an intelligent being and simultaneously the trapdoor has been closed. (B) Work has been accomplished by the gas expansion. (C) The trapdoor has been opened and simultaneously the load has been uncoupled and supported. (D) The piston has been moved to a central position. The cycle recommences at A with the gas molecule on the same or opposite side of the piston.</p>
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<p>The device of Popper as perceived by the author<a href="#fn001-entropy-06-00038" class="html-fn">1</a>. The same operations as in Szilard’s device (<a href="#entropy-06-00038-f001" class="html-fig">Fig. 1</a>) except a converter is added to replace the intelligent <span class="html-italic">being</span>. The Plate P attached to the piston rod pushes or pulls the plates fixed to the converter belt. (See the text for details.)</p>
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<p>A device as described in <a href="#entropy-06-00038-f002" class="html-fig">Fig. 2</a> but with an additional wheel that is fixed to the axle of a converter wheel and makes a second linkage (one of control via a pawl and trapdoor) between the converter and the Szilard engine. The first linkage is via the piston rod.</p>
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<p>Plan view of the device illustrated in <a href="#entropy-06-00038-f003" class="html-fig">Fig. 3</a>. The pawl and the trapdoor are fixed to the same axle lying vertically in the plane of the paper. The pawl is engaged, the trapdoor is open (not shown) at indicated position.</p>
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138 KiB  
Article
Thomson's formulation of the second law for macroscopic and finite work sources
by Armen E. Allahverdyan, Roger Balian and Theo M. Nieuwenhuizen
Entropy 2004, 6(1), 30-37; https://doi.org/10.3390/e6010030 - 18 Mar 2004
Cited by 5 | Viewed by 5821
Abstract
Thomson's formulation of the second law states: no work can be extracted from an equilibrium system through a cyclic process. A simple, general proof is presented for the case of macroscopic sources of work. Next the setup is generalized towards situations, where the [...] Read more.
Thomson's formulation of the second law states: no work can be extracted from an equilibrium system through a cyclic process. A simple, general proof is presented for the case of macroscopic sources of work. Next the setup is generalized towards situations, where the corresponding work-source is not macroscopic. It is shown that using such a source one can extract energy from an equilibrium system by means of a cyclic process. However, this extraction is accompanied by an entropy increase of the source, in a manner resembling the Clausius inequality. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
256 KiB  
Article
On Expansion of a Spherical Enclosure Bathed in Zero-Point Radiation
by Jirí J. Mares, Václav Spicka, Jozef Kristofik and Pavel Hubik
Entropy 2004, 6(1), 216-222; https://doi.org/10.3390/e6010216 - 17 Mar 2004
Viewed by 5464
Abstract
In the present contribution a simple thought experiment made with an idealized spherical enclosure bathed in zero-point (ZP) electromagnetic radiation and having walls made of a material with an upper frequency cut-off has been qualitatively analysed. As a result, a possible mechanism of [...] Read more.
In the present contribution a simple thought experiment made with an idealized spherical enclosure bathed in zero-point (ZP) electromagnetic radiation and having walls made of a material with an upper frequency cut-off has been qualitatively analysed. As a result, a possible mechanism of filling real cavities with ZP radiation based on Doppler's effect has been suggested and corresponding entropy changes have been discussed. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>Illustration of trapping of the ZP radiation by expanding spherical enclosure based on Doppler’s effect. The shell of the enclosure is made of reflecting material with the cut-off frequency <span class="html-italic">ω<sub>K</sub></span>.</p>
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171 KiB  
Article
Second Law Violation By Magneto-Caloric Effect Adiabatic Phase Transition of Type I Superconductive Particles
by Peter Keefe
Entropy 2004, 6(1), 116-127; https://doi.org/10.3390/e6010116 - 17 Mar 2004
Cited by 13 | Viewed by 6733
Abstract
The nature of the thermodynamic behavior of Type I superconductor particles, having a cross section less than the Ginzburg-Landau temperature dependent coherence length is discussed for magnetic field induced adiabatic phase transitions from the superconductive state to the normal state. Argument is advanced [...] Read more.
The nature of the thermodynamic behavior of Type I superconductor particles, having a cross section less than the Ginzburg-Landau temperature dependent coherence length is discussed for magnetic field induced adiabatic phase transitions from the superconductive state to the normal state. Argument is advanced supporting the view that when the adiabatic magneto-caloric process is applied to particles, the phase transition is characterized by a decrease in entropy in violation of traditional formulations of the Second Law, evidenced by attainment of a final process temperature below that which would result from an adiabatic magneto-caloric process applied to bulk dimensioned specimens. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>The thermodynamic state of a bulk dimensioned tin specimen during an adiabatic phase transition is illustrated using equations developed in part A of the Discussion, where the starting temperature is .65T<sub>C</sub>. Shown is the variation in superconductive phase volume as a function of reduced temperature during a bulk size specimen adiabatic magneto-caloric process starting in the superconductive phase and ending in the normal phase. The final temperature achieved is 0.416T<sub>C</sub>.</p>
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<p>The adiabatic magneto-caloric effect phase transition dependency on specimen cross-section is indicated by plotting the variation in the process reduced final temperature, T<sub>f</sub>, as a function of specimen thickness in units of ξ(T). For reference, the final temperature for a bulk dimensioned specimen adiabatic magneto-caloric effect is 0.348T<sub>c</sub>, and the lowest T<sub>f</sub> plotted is 0.174T<sub>c</sub>. For all T<sub>f</sub> lower than 0.348T<sub>c</sub>, the Second Law is violated.</p>
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150 KiB  
Article
Internal Structure of Elementary Particle and Possible Deterministic Mechanism of Biological Evolution
by Alexei V. Melkikh
Entropy 2004, 6(1), 223-232; https://doi.org/10.3390/e6010223 - 16 Mar 2004
Cited by 2 | Viewed by 7147
Abstract
The possibility of a complicated internal structure of an elementary particle was analyzed. In this case a particle may represent a quantum computer with many degrees of freedom. It was shown that the probability of new species formation by means of random mutations [...] Read more.
The possibility of a complicated internal structure of an elementary particle was analyzed. In this case a particle may represent a quantum computer with many degrees of freedom. It was shown that the probability of new species formation by means of random mutations is negligibly small. Deterministic model of evolution is considered. According to this model DNA nucleotides can change their state under the control of elementary particle internal degrees of freedom. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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414 KiB  
Article
A New Thermodynamics from Nuclei to Stars
by Dieter H.E. Gross
Entropy 2004, 6(1), 158-179; https://doi.org/10.3390/e6010158 - 16 Mar 2004
Cited by 21 | Viewed by 7900
Abstract
Equilibrium statistics of Hamiltonian systems is correctly described by the microcanonical ensemble. Classically this is the manifold of all points in the N-body phase space with the given total energy. Due to Boltzmann's principle, eS=tr(δ(E-H)), its geometrical size is related to [...] Read more.
Equilibrium statistics of Hamiltonian systems is correctly described by the microcanonical ensemble. Classically this is the manifold of all points in the N-body phase space with the given total energy. Due to Boltzmann's principle, eS=tr(δ(E-H)), its geometrical size is related to the entropy S(E,N,...). This definition does not invoke any information theory, no thermodynamic limit, no extensivity, and no homogeneity assumption, as are needed in conventional (canonical) thermo-statistics. Therefore, it describes the equilibrium statistics of extensive as well of non-extensive systems. Due to this fact it is the fundamental definition of any classical equilibrium statistics. It can address nuclei and astrophysical objects as well. All kind of phase transitions can be distinguished sharply and uniquely for even small systems. It is further shown that the second law is a natural consequence of the statistical nature of thermodynamics which describes all systems with the same -- redundant -- set of few control parameters simultaneously. It has nothing to do with the thermodynamic limit. It even works in systems which are by far than any thermodynamic "limit". Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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Figure 1
<p>Global phase diagram or contour plot of the curvature determinant (Hessian), eqn. (7), of the 2-dim Potts-3 lattice gas with 50 ∗ 50 lattice points, <span class="html-italic">n</span> is the number of particles per lattice point, <span class="html-italic">e</span> is the total energy per lattice point. The line (-2,1) to (0,0) is the ground-state energy of the lattice-gas as function of <span class="html-italic">n</span>. The most right curve is the locus of configurations with completely random spin-orientations (maximum entropy). The whole physics of the model plays between these two boundaries. At the dark-gray lines the Hessian is det = 0,this is the boundary of the region of phase separation (the triangle <span class="html-italic">AP<sub>m</sub>B</span>) with a negative Hessian (<span class="html-italic">λ</span><sub>1</sub> &gt; 0, <span class="html-italic">λ</span><sub>2</sub> &lt; 0). Here, we have Pseudo-Riemannian geometry. At the light-gray lines is a minimum of det(<span class="html-italic">e</span><span class="html-italic">, n</span>) in the direction of the largest curvature (v<sub><span class="html-italic">λ<sub>max</sub></span></sub> · ∇det = 0) and det = 0,these are lines of second order transition. In the triangle <span class="html-italic">AP<sub>m</sub>C</span> is the pure ordered (solid) phase (det &gt; 0, <span class="html-italic">λ</span><sub>1</sub> &lt; 0). Above and right of the line <span class="html-italic">CP<sub>m</sub>B</span> is the pure disordered (gas) phase (det &gt; 0, <span class="html-italic">λ</span><sub>1</sub> &lt; 0). The crossing <span class="html-italic">P<sub>m</sub></span> of the boundary lines is a multi-critical point. It is also the critical end-point of the region of phase separation (det &lt; 0, <span class="html-italic">λ</span><sub>1</sub> &gt; 0, <span class="html-italic">λ</span><sub>2</sub> &lt; 0). The light-gray region around the multi-critical point <span class="html-italic">P<sub>m</sub></span> corresponds to a flat, horizontal region of det(<span class="html-italic">e</span>, <span class="html-italic">n</span>) ∼ 0 and consequently to a somewhat extended cylindrical region of <span class="html-italic">s</span>(<span class="html-italic">e</span>, <span class="html-italic">n</span>) and ∇<span class="html-italic">λ</span><sub>1</sub>∼ 0, details see [<a href="#B6-entropy-06-00158" class="html-bibr">6</a>, <a href="#B7-entropy-06-00158" class="html-bibr">7</a>]; <span class="html-italic">C</span> is the analytically known position of the critical point which the ordinary <span class="html-italic">q</span> = 3 Potts model (without vacancies) <span class="html-italic">would have in the thermodynamic limit</span></p>
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<p>MMMC [<a href="#B7-entropy-06-00158" class="html-bibr">7</a>] simulation of the entropy <span class="html-italic">s</span>(<span class="html-italic">e</span>) per atom (<span class="html-italic">e</span> in eV per atom) of a system of <span class="html-italic">N</span><sub>0</sub> = 1000 sodium atoms at an external pressure of 1 atm. At the energy <span class="html-italic">e</span> ≤ <span class="html-italic">e</span><sub>1</sub> the system is in the pure liquid phase and at <span class="html-italic">e</span> ≥ <span class="html-italic">e</span><sub>3</sub> in the pure gas phase, of course with fluctuations. The latent heat per atom is <span class="html-italic">q<sub>lat</sub></span> = <span class="html-italic">e</span><sub>3</sub> − <span class="html-italic">e</span><sub>1</sub>. <span class="underline">Attention:</span> the curve <span class="html-italic">s</span>(<span class="html-italic">e</span>) is artificially sheared by subtracting a linear function 25 + <span class="html-italic">e</span>∗11.5 in order to make the convex intruder visible. <span class="html-italic">s</span>(<span class="html-italic">e</span>) <span class="html-italic">is always a steep monotonic rising function</span>. We clearly see the global concave (downwards bending) nature of <span class="html-italic">s</span>(<span class="html-italic">e</span>) and its convex intruder. Its depth is the entropy loss due to additional correlations by the interfaces. It scales ∝ <span class="html-italic">N</span><sup>−1/3</sup> . From this one can calculate the surface tension per surface atom <span class="html-italic">σ<sub>surf</sub></span>/<span class="html-italic">T<sub>tr</sub></span> = ∆<span class="html-italic">s<sub>surf</sub></span> ∗ <span class="html-italic">N</span><sub>0</sub>/<span class="html-italic">N<sub>surf</sub></span>. The double tangent (Gibbs construction) is the concave hull of <span class="html-italic">s</span>(<span class="html-italic">e</span>). Its derivative gives the Maxwell line in the caloric curve <span class="html-italic">T</span>(<span class="html-italic">e</span>) at <span class="html-italic">T<sub>tr</sub></span>. In the thermodynamic limit the intruder would disappear and <span class="html-italic">s</span>(<span class="html-italic">e</span>) would approach the double tangent from below. Nevertheless, even there, the probability ∝ <span class="html-italic">e<sup>Ns</sup></span> of configurations with phase-separations are suppressed by the (infinitesimal small) factor <math display="inline"> <semantics> <mrow> <msup> <mi>e</mi> <mrow> <mo>−</mo> <msup> <mi>N</mi> <mrow> <mn>2</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mrow> </msup> </mrow> </semantics> </math> relative to the pure phases and the distribution remains <span class="html-italic">strictly</span> <span class="html-italic">bimodal</span><span class="html-italic">in the canonical ensemble</span>. The region <span class="html-italic">e</span><sub>1</sub> &lt; <span class="html-italic">e</span> &lt; <span class="html-italic">e</span><sub>3</sub> of phase separation gets lost.</p>
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<p>Potts model, (<span class="html-italic">q</span> = 10) in the region of phase separation. At <span class="html-italic">e</span><sub>1</sub> the system is in the pure ordered phase, at <span class="html-italic">e</span><sub>3</sub> in the pure disordered phase. A little above <span class="html-italic">e</span><sub>1</sub> the temperature <span class="html-italic">T</span> = 1<span class="html-italic">/β</span> is higher than a little below <span class="html-italic">e</span><sub>3</sub>. Combining two parts of the system: one at the energy <span class="html-italic">e</span><sub>1</sub> + <span class="html-italic">δe</span> and at the temperature <span class="html-italic">T</span><sub>1</sub>, the other at the energy <span class="html-italic">e</span><sub>3</sub> − <span class="html-italic">δe</span> and at the temperature <span class="html-italic">T</span><sub>3</sub><span class="html-italic">&lt; T</span><sub>1</sub> will equilibrize with a rise of its entropy, a drop of <span class="html-italic">T</span><sub>1</sub> (cooling) and an energy flow (heat) from 3 → 1: i.e.: Heat flows from cold to hot! Clausius formulation of the second law is violated. Evidently, this is not any peculiarity of gravitating systems! This is a generic situation within classical thermodynamics even of systems with short-range coupling and <span class="html-italic">has nothing to do with long range interaction.</span></p>
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<p>Experimental excitation energy per nucleon <span class="html-italic">e</span>* versus apparent temperature <span class="html-italic">T<sub>app</sub></span> for backward <span class="html-italic">p</span>, <span class="html-italic">d</span>, <span class="html-italic">t</span> and <span class="html-italic">α</span> together with heavy evaporation residues out of incomplete fusion of 701 Mev <sup>28</sup>Si+<sup>100</sup>Mo. The dotted curves give the Fermi-gas caloric curves for the level-density parameter a = 6 to 12. (Chbihi et al. Eur.Phys.J. A 1999)</p>
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<p>Cluster fragmentation</p>
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<p>Phases and Phase-Separation in Rotating, Self-Gravitating Systems, Physical Review Letters–July 15, 2002, cover-page, by (Votyakov, Hidmi, De Martino, Gross)</p>
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<p>Microcanonical phase-diagram of a cloud of self-gravitating and rotating system as function of the energy and angular-momentum. Outside the dashed boundaries only some singular points were calculated. In the mixed phase the largest curvature <span class="html-italic">λ</span><sub>1</sub> of <span class="html-italic">S</span>(<span class="html-italic">E</span>, <span class="html-italic">L</span>) is positive. Consequently the heat capacity or the correspondent susceptibility is negative. This is of course well known in astrophysics. However, the new and important point of our finding is that within microcanonical thermodynamics this is <span class="html-italic">a generic property of all phase transitions of first order, independently of whether there is a short- or a long-range force that organizes the system</span>.</p>
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<p>The compact set <math display="inline"> <semantics> <mrow> <mi mathvariant="bold-italic">M</mi> <mrow> <mo>(</mo> <mrow> <msub> <mi mathvariant="bold-italic">t</mi> <mn mathvariant="bold">0</mn> </msub> </mrow> <mo>)</mo> </mrow> </mrow> </semantics> </math>, left side, develops into an increasingly folded “spaghetti”-like distribution in phase-space with rising time <span class="html-italic">t</span>, Gibbs’ ”ink-lines”. The right figure shows only the early form of the distribution. At much larger times it will become more and more fractal and finally dense in the new phase space. The grid illustrates the boxes of the box-counting method. All boxes which overlap with <math display="inline"> <semantics> <mrow> <mi mathvariant="bold-italic">M</mi> <mrow> <mo>(</mo> <mi mathvariant="bold-italic">t</mi> <mo>)</mo> </mrow> </mrow> </semantics> </math> are counted in <b><span class="html-italic">N<sub>δ</sub></span></b> in eq.(20)</p>
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108 KiB  
Article
Entropic localization in non-unitary Newtonian gravity
by Sergio Filippo De and Filippo Maimone
Entropy 2004, 6(1), 153-157; https://doi.org/10.3390/e6010153 - 16 Mar 2004
Cited by 6 | Viewed by 5180
Abstract
The localizing properties and the entropy production of the Newtonian limit of a nonunitary version of fourth order gravity are analyzed. It is argued that pure highly unlocalized states of the center of mass motion of macroscopic bodies rapidly evolve into unlocalized ensembles [...] Read more.
The localizing properties and the entropy production of the Newtonian limit of a nonunitary version of fourth order gravity are analyzed. It is argued that pure highly unlocalized states of the center of mass motion of macroscopic bodies rapidly evolve into unlocalized ensembles of highly localized states. The localization time and the final entropy are estimated. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
73 KiB  
Article
A Concise Equation of State for Aqueous Solutions of Electrolytes Incorporating Thermodynamic Laws and Entropy
by Raji Heyrovská
Entropy 2004, 6(1), 128-132; https://doi.org/10.3390/e6010128 - 16 Mar 2004
Cited by 4 | Viewed by 6054
Abstract
Recently, the author suggested a simple and composite equation of state by incorporating fundamental thermodynamic properties like heat capacities into her earlier concise equation of state for gases based on free volume and molecular association / dissociation. This work brings new results for [...] Read more.
Recently, the author suggested a simple and composite equation of state by incorporating fundamental thermodynamic properties like heat capacities into her earlier concise equation of state for gases based on free volume and molecular association / dissociation. This work brings new results for aqueous solutions, based on the analogy of the equation of state for gases and solutions over wide ranges of pressures (for gases) and concentrations (for solutions). The definitions of entropy and heat energy through the equation of state for gases, also holds for solutions. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
240 KiB  
Article
Modified Feynman ratchet with velocity-dependent fluctuations
by Jack Denur
Entropy 2004, 6(1), 76-86; https://doi.org/10.3390/e6010076 - 15 Mar 2004
Cited by 7 | Viewed by 7924
Abstract
The randomness of Brownian motion at thermodynamic equilibrium can be spontaneously broken by velocity-dependence of fluctuations, i.e., by dependence of values or probability distributions of fluctuating properties on Brownian-motional velocity. Such randomness-breaking can spontaneously obtain via interaction between Brownian-motional Doppler effects --- which [...] Read more.
The randomness of Brownian motion at thermodynamic equilibrium can be spontaneously broken by velocity-dependence of fluctuations, i.e., by dependence of values or probability distributions of fluctuating properties on Brownian-motional velocity. Such randomness-breaking can spontaneously obtain via interaction between Brownian-motional Doppler effects --- which manifest the required velocity-dependence --- and system geometrical asymmetry. A non random walk is thereby spontaneously superposed on Brownian motion, resulting in a systematic net drift velocity despite thermodynamic equilibrium. The time evolution of this systematic net drift velocity --- and of velocity probability density, force, and power output --- is derived for a velocity-dependent modification of Feynman's ratchet. We show that said spontaneous randomness-breaking, and consequent systematic net drift velocity, imply: bias from the Maxwellian of the system's velocity probability density, the force that tends to accelerate it, and its power output. Maximization, especially of power output, is discussed. Uncompensated decreases in total entropy, challenging the second law of thermodynamics, are thereby implied. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>Modified Feynman ratchet with velocity-dependent fluctuations.</p>
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179 KiB  
Article
From Randomness to Order
by Jorge Berger
Entropy 2004, 6(1), 68-75; https://doi.org/10.3390/e6010068 - 12 Mar 2004
Cited by 2 | Viewed by 6023
Abstract
I review some selected situations in which order builds up from randomness, or a losing trend turns into winning. Except for Section 4 (which is mine), all cases are well documented and the price paid to achieve order is apparent. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>Model considered in Ref. [<a href="#B3-entropy-06-00068" class="html-bibr">3</a>]. The dashed lines are transparent to the molecules and rigid to the piston.</p>
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<p>Potential energy of the particle, as a function of position, at some fixed time.</p>
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<p>Superconducting loop, composed of two unequal segments, that encloses a magnetic flux Φ. V is the average voltage between the points where both segments meet.</p>
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<p>Voltage between the extremes of the segments of the superconducting loop. The voltage is an odd function of the magnetic flux Φ, and is periodic with period Φ<sub>0</sub>, where Φ<sub>0</sub> = 2.07×10<sup>-15</sup> Tm<sup>2</sup> is the quantum of flux.</p>
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585 KiB  
Article
Langevin approach to the Porto system
by Jirí Bok and Vladislav Cápek
Entropy 2004, 6(1), 57-67; https://doi.org/10.3390/e6010057 - 12 Mar 2004
Cited by 8 | Viewed by 5361
Abstract
M. Porto (Phys. Rev. E 63 (2001) 030102) suggested a system consisting of Coulomb interacting particles, forming a linear track and a rotor, and working as a molecular motor. Newton equations with damping for the rotor coordinate on the track x, with a [...] Read more.
M. Porto (Phys. Rev. E 63 (2001) 030102) suggested a system consisting of Coulomb interacting particles, forming a linear track and a rotor, and working as a molecular motor. Newton equations with damping for the rotor coordinate on the track x, with a prescribed time-dependence of the rotor angle Θ, indicated unidirectional motion of the rotor. Here, for the same system, the treatment was generalized to nonzero temperatures by including stochastic forces and treating both x and Θ via two coupled Langevin equations. Numerical results are reported for stochastic homogeneous distributions of impact events and Gaussian distributions of stochastic forces acting on both the variables. For specific values of parameters involved, the unidirectional motion of the rotor along the track is confirmed, but with a mechanism that is not necessarily the same as that one by Porto. In an additional weak homogeneous potential field U(x)=const.x acting against the motion, the unidirectional motion persists. Then the rotor accumulates potential energy at the cost of thermal stochastic forces from the bath. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>Plot of the dimensionless rotor-track potential energy <span class="html-italic">ψ</span> for <span class="html-italic">γ</span> = +1 as a function of <span class="html-italic">X</span> and Θ.</p>
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<p>Time dependence of angle Θ as a function of <span class="html-italic">T</span> for <span class="html-italic">γ</span> = +1 and the same values of all the input parameters as specified in the main text. In all three cases, the impact times as well as the random forces were identical. Only in time intervals between any two individual impacts, different integration time steps (1/32, 1/16, 1/10, 1/8 and 1/7 for curves a) to e), respectively) were used. The onset of chaos appears at about <span class="html-italic">T</span> = 1200. At <span class="html-italic">T</span> = 1000, the values of Θ obtained still coincided to 5 digits.</p>
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<p>The same for <span class="html-italic">X</span> as a function of <span class="html-italic">T</span> for the same values of all the input parameters. At <span class="html-italic">T</span> = 1000, the values of <span class="html-italic">X</span> obtained still coincided to 6 digits. Notice that all the curves increase with increasing time.</p>
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<p>Dependence of X on T for five different sequences of the random numbers involved for the ‘forward gear’ <span class="html-italic">γ</span> = +1.</p>
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<p>The same for the ‘reverse gear’ <span class="html-italic">γ</span> = −1. The same sequences of random numbers as in <a href="#entropy-06-00057-f004" class="html-fig">Figure 4</a> were used.</p>
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<p>Details of time-dependence of <span class="html-italic">X</span>(<span class="html-italic">T</span>) (<span class="html-italic">γ</span> = +1) for curve ‘c’ of <a href="#entropy-06-00057-f004" class="html-fig">Figure 4</a> before the first impact event in Θ occurs. Times <span class="html-italic">T</span> of the first six impacts in <span class="html-italic">X</span> were 4.4506, 5.0489, 5.9216, 9.7589, 9.9581, and 10.7401. The first impact in Θ appears at <span class="html-italic">T</span> = 216.8751. Worth noticing is how the impacts cause, because of the periodicity of <span class="html-italic">ψ</span>, sudden changes of <span class="html-italic">X</span> = <span class="html-italic">x</span>/<span class="html-italic">b</span> (on the vertical axis) by integers.</p>
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<p>Dependence of X on T for five different sequences of the random numbers involved for the ‘forward gear’ <span class="html-italic">γ</span> = +1. All the input parameters as well as the random forces were identical as in <a href="#entropy-06-00057-f004" class="html-fig">Figure 4</a>, but with the linear potential <span class="html-italic">c</span> · <span class="html-italic">X</span>, <span class="html-italic">c</span> = 0.01 added to <span class="html-italic">ψ</span>(<span class="html-italic">X</span>, Θ).</p>
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Article
The adiabatic piston: a perpetuum mobile in the mesoscopic realm
by Bruno Crosignani, Paolo Porto Di and Claudio Conti
Entropy 2004, 6(1), 50-56; https://doi.org/10.3390/e6010050 - 11 Mar 2004
Cited by 9 | Viewed by 8772
Abstract
A detailed analysis of the adiabatic-piston problem reveals, for a finely-tuned choice of the spatial dimensions of the system, peculiar dynamical features that challenge the statement that an isolated system necessarily reaches a time-independent equilibrium state. In particular, the piston behaves like a [...] Read more.
A detailed analysis of the adiabatic-piston problem reveals, for a finely-tuned choice of the spatial dimensions of the system, peculiar dynamical features that challenge the statement that an isolated system necessarily reaches a time-independent equilibrium state. In particular, the piston behaves like a perpetuum mobile, i.e., it never comes to a stop but keeps wandering, undergoing sizeable oscillations around the position corresponding to maximum entropy; this has remarkable implications on the entropy changes of a mesoscopic isolated system and on the limits of validity of the second law of thermodynamics in the mesoscopic realm. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>The adiabatic piston: an insulating cylinder divided into two regions A and B by a movable, frictionless, insulating piston. T<sub>A</sub>, T<sub>B</sub> and P<sub>A</sub>,P<sub>B</sub> are the initial temperatures and pressures in the two sections.</p>
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<p>Time evolution of the normalized root-mean-square deviation of the piston position from its initial normalized value ξ(0)=1/2, for M/M<sub>g</sub>=0.5 and N=3x10<sup>4</sup>, over 1000 realizations.</p>
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<p>Time evolution of the normalized entropy change, for the same case as in <a href="#entropy-06-00050-f002" class="html-fig">Fig.2</a>.</p>
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<p>Normalized entropy change as a function of μ=M/M<sub>g</sub> for N=3x10<sup>4</sup>, averaged over 1000 realizations (dots). The continuous line is after Eq. (4).</p>
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Article
The Deep Physics Behind the Second Law: Information and Energy As Independent Forms of Bookkeeping
by Todd L. Duncan and Jack S. Semura
Entropy 2004, 6(1), 21-29; https://doi.org/10.3390/e6010021 - 11 Mar 2004
Cited by 16 | Viewed by 8170
Abstract
Even after over 150 years of discussion, the interpretation of the second law of thermodynamics continues to be a source of confusion and controversy in physics. This confusion has been accentuated by recent challenges to the second law and by the difficulty in [...] Read more.
Even after over 150 years of discussion, the interpretation of the second law of thermodynamics continues to be a source of confusion and controversy in physics. This confusion has been accentuated by recent challenges to the second law and by the difficulty in many cases of clarifying which formulation is threatened and how serious the implications of a successful challenge would be. To help bring clarity and consistency to the analysis of these challenges, the aim of this paper is to suggest a simple formulation of the deep physics of the second law, and to point out how such a statement might help us organize the challenges by level of seriousness. We pursue the notion that the second law is ultimately a restriction operating directly on the dynamics of information, so the existence of this law can be traced to the need for a system of "information bookkeeping" that is independent of the bookkeeping for energy. Energy and information are related but independent, so the dynamical restrictions for one cannot be derived from those for the other. From this perspective, we also suggest the possibility that the foundation of the second law may be linked to the finite capacity of nature to store bookkeeping information about its own state. Full article
(This article belongs to the Special Issue Quantum Limits to the Second Law of Thermodynamics)
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<p>When energy and information are exchanged between two systems, the dynamics of energy exchange does not uniquely determine the information exchanged.</p>
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