Questions tagged [thermodynamics]

Covers the study of (primarily homogeneous) macroscopic systems from a heat/energy/entropy point of view. Consider also using the tag: [statistical-mechanics].

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Can Lee-Yang zeros theorem account for triple point phase transition?

Now the prominent Lee-Yang theorem (or Physical Review 87, 410, 1952) has almost become a standard ingredient of any comprehensive statistical mechanics textbook. If the volume tends to infinity, ...
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Phil Anderson's Criticism of Existence of Stable Dissipative Structures

In this book chapter (1987), titled "Broken symmetry, emergent properties, dissipative structures, life," Phil Anderson and Daniel Stein criticize defining life as a dissipative structure (a ...
stochastic's user avatar
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Demystifying jamming in many-body systems

From a theoretical point of view, what has been the most successful approach to understanding jamming phenomena? I understand there's still a lot of debate around this subject, namely whether a ...
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Radiative equilibrium in orbit of a black hole

According to Life under a black sun, Miller's planet from Interstellar, with a time dilation factor of 60,000, should be heated to around 890C by blue-shifted cosmic background radiation. How they ...
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Quantum pressure and chemical potential for a Schwarzschild black hole?

Just as Hawking showed that even Schwarzschild black holes have a temperature, shouldn't they also have a pressure and chemical potential? Are there any analytical formulae of those as well as $$ T_{...
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Photon pumping in Laser

Let's consider a ring laser where the laser must pass through the gain material before it is sent toward a partially reflective surface $\ R=1-T $. The other mirrors are perfect reflectors with $\ R_1=...
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Why there is no chemical potential on this thermodynamic relation?

I was following the book by Landau and Lifshitz, Fluid Mechanics (2nd edition) and got stuck trying to understand one of their arguments. On the chapter about Relativistic Fluid Dynamics it is stated ...
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How does adiabatic cooling make a nebula colder than the CMB?

According to measurements, the gas from the Boomerang Nebula is expanding so fast that it's colder than the cosmic microwave background radiation... how does such a simple mechanic work on such a ...
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Time for which a drop stays in the leidenfrost point

Is there any way to find out the time required for a drop of given dimensions to vaporize after attaining Leidenfrost point?
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Relation between maximally mixed state and thermal state

Hawking calculated the density matrix of the outgoing radiation to be a thermal state. I have heard people say this is a maximally mixed state. Is this because given a fixed average energy in the ...
Weyl Dog 's user avatar
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How does renormalization relate to emergence?

In statistical mechanics renormalization is often related to coarse-graining which in turn allows to calculate some macroscopic states. The resulting macroscopic description is sometimes called ...
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Can a substance have zero vapour pressure above absolute zero?

According to this Reddit thread, the answer is no, vapor pressure can't be zero when temperature is above absolute zero. I suspect the answer might actually be yes according to a precise definition I ...
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Are order parameters ultimately subjective?

I keep bumping into order parameters in scientific papers, reviews, articles, etc, but I can never get a firm grip on them. Order parameters seem terribly subjective to me. Basically the way I ...
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On Ricci flow and 'nonlinear relativistic heat equation

This is somewhat related to a previous question, but is different at the core. I proposed a Relativistic Ricci flow equation that takes the form $$\frac{\partial R}{\partial t} = \alpha \Box^2 R = -...
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Violations of Onsager reciprocity?

As far as I understand it, the modern statement of Onsager reciprocity is that the linear-response transport coefficient matrix, when transposed, is equal to that of the time-reversed system (reversed ...
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What is the link between free energy and lagrangian?

Free energy is a generalization of energy when the system exchanges heat with the environment. Energy, in its turn, can be extracted from lagrangian under the symmetry of time $(\frac{\partial L}{\...
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The surface area to volume ratio of a sphere and the Bekenstein bound

I am trying to relate the surface-area-to-volume-ratio of a sphere to the Bekenstein bound. Since the surface-area-to-volume-ratio decreases with increasing volume, one would surmise that, per unit of ...
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Thermodynamic inaccessibility and its consequences

Caratheodory's principle, namely, that in any neighborhood of an arbitrary equilibrium state there are states not accessible via adiabatic reversible path, leads to the existence of an integrating ...
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Saddle point contributions to the gravitational path integral

In his lectures on black holes and quantum information, Tom Hartman states that the gravitational path integral can be approximated as $$ Z(\beta) \approx \sum_{g_\text{cl}} e^{-I_E[g_\text{cl}, \phi]}...
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Why one-particle irreducible functional is closely related to pressure (electroweak phase transition)?

Consider the following system: the SM lagrangian somewhat below the EW transition, where we keep only bilinear terms, only the heaviest fermion -- $t$-quark, and plus the potential terms for a VEV $\...
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Apparent contradictions in stability conditions for diamagnetic materials

I was looking at Herbert B Callen's book on thermodynamics, specially Chapter 8 on the Stability of Thermodynamic systems. In it, he states that for a system to be in a stable thermodynamical ...
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Unruh effect, temperature and energy density

The Unruh effect basically states that an accelerated observer will see warm gas of particles following a blackbody distribution with some temperature T, where as an inertial observer would see none. ...
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Nose-Hoover Barostat

Much can be found about the Nose-Hoover Thermostat. However I seem to be having difficulty finding out details about the Nose-Hoover Barostat, and how it is implemented. Would anyone be able to give ...
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Validity of topological thermodynamics?

I've been reading some material by R. Kiehn, developing a topological approach to non-equilibrium thermodynamics through Cartan forms, where the fundamental claim is that irreversible processes are ...
Robert Mastragostino's user avatar
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Lattice model completely constrained by boundary data

I am dealing with a lattice model that has the peculiar property that if I specify all the spins on the boundary, by local conservation laws, the whole lattice configuration (throughout the whole ...
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An explanation for the Landauer's principle

Has anyone understood the Landauer's principle? What is the current status? In specific, is there a theoretical derivation of the Landauer's Principle?(not the heuristic one based on Salizard's ...
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experiment proposal to validate microcausality

I've been wondering about microcausality for some time now (a recent question of mine regarding the topic) and i'm wondering if its possible to devise an experiment to detect potential violations I ...
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Freshman-level justification for the use of $(x,p)$ in thermodynamic phase space

I'm looking for an elementary explanation, at the freshman level, of why we use position and momentum for phase space rather than, say, position and velocity. At this level, it's not going to work to ...
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Calculate the entropy per atom in Bohmian Mechanics

Bohmian mechanics description of a large number of interacting atoms would require a large phase space due to the large number of classical degrees of freedom. The entropy per atom is given as the ...
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Bose-Einstein condensation and phase transition

I would like to ask the following question for which I cannot find a definite answer in the literature. Of what ORDER is the phase transition leading to Bose-Einstein condensation for a ideal and ...
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Long-range fluctuations induced forced (or the classical Casimir effect)

According to literature, the Casimir effect refers to attraction of two parallel neutral metal plates due to the wavelength cutoff of quantum fluctuations between the two plates. I come from condensed ...
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In statistical mechanics, why is one "allowed" to treat classical systems probabilistically?

Is the essential argument that these systems are microscopically chaotic enough that we can approximate their evolution as random (vastly simplifying calculations) and still make accurate experimental ...
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Empirical equivalence of shifted chemical potential $\mu_i$

It is often said that, in classical thermodynamics, entropy $S$ and energy $U$ are defined only up to an additive constant proportional to the total amount of substance $N=\sum_i N_i$ (where the sum ...
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How is this paper published in Physical Review E not claiming to break the second law of thermodynamics?

This paper has the following abstract: We theoretically consider a graphene ripple as a Brownian particle coupled to an energy storage circuit. When circuit and particle are at the same temperature, ...
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Can an LED emit photons with energy (in $\rm eV$) larger than the voltage drop across it (in $\rm V$)?

I recently had a discussion with someone who told me that they have a UVC (260 nm - 270 nm) LED with a forward voltage of 3.3 V. I told them that this must be impossible, because an electron dropping ...
MaxParadiz's user avatar
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How large is large $N$?

I once heard Lenny Susskind relate the question: "how many particles do you need in a box for the ideal gas law to 'pretty much' hold?" Obviously this question requires a notion of 'pretty ...
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How to obtain hydrodynamics from many-body quantum mechanics?

Background: It is well known that the Schrodinger equation is equivalent to the Euler equation (with a "quantum potential" term) plus the probability conservation equation (which is formally ...
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When is temperature not equal to average kinetic energy?

Defining temperature $T\equiv\left(∂S/∂U\right)^{-1}$ is universal. It applies even with negative temperature. Except for negative temperature, when does defining temperature as average kinetic ...
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Why is the Fokker-Planck equation only valid for the forward and backward velocities but not for the flux velocity?

I noticed that the Fokker-Planck equation is often only written for the forward velocity $\vec b$ and the backward velocity $\vec b^*$: \begin{align} \partial_t \rho + \nabla (\vec b \rho) &= D \...
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What happens to topological insulators at finite temperature?

There is a similar question here, but I had a few things I wanted to ask. So basically pretty much all analysis/ theory of topological insulators is for pure wave-functions and conservative ...
Janet Zhong's user avatar
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Bose Condensation; interacting vs. non-interacting

I have some problems unifying, the two way I learned how a Bose condensate appears. The main problem is that the observables seem to be quite different. In statistical physics lecture one starts with ...
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Grand potential physical meaning

Take the classical Grand canonical ensemble. Its grand potential $J$ could be defined as: $$J=\langle U \rangle-T\langle S \rangle-\mu\langle N\rangle = \langle F\rangle-\mu\langle N\rangle$$ $F$, ...
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Bekenstein bound and "dimensionality" of information (entropy)

The Bekenstein bound says that the maximum entropy which can be contained in a (spherical) volume of space with a given amount of energy is proportional to the amount of energy multiplied by the "...
Robin Saunders's user avatar
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Is there an equation of state for a non-ideal Fermi gas?

For a gas of self-interacting electrons (i.e. a non-ideal Fermi gas), is there is there any sense in trying to define an equation of state? If so, what is the equation of state for a gas of electrons? ...
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How to calculate the energy transfer between working coil and working piece and dissipated energy of working piece in induction heating?

For who don't know how does induction heating work, a short description can be found here. However, my question is about physics. Assume I have a coil inductor calculated carefully 50 uH as below: ...
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Thermodynamic equilibrium or thermal equilibrium and equipartition theorem

In all derivations of the equipartition theorem I can find a thermodynamic equilibrium distribution is used to show it's validity. But more vague sources (physics.stackexchange answer by Luboš Motl, ...
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What happens to the observed thermal energy of objects at relativistic speeds?

When an object is observed to move near the speed of light, what difference in thermal energy is observed? Does time dilation imply that it's colder?
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Experimental results regarding non-extensivity in small systems

From a statistical mechanics point of view, the extensivity of thermodynamics arises from the fact that we can neglect interaction terms in the Hamiltonian. This allows us to infer that when we put ...
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What groups of symmetry are most suited for filling uniformely a spherical 3D space, whilst possessing the lowest possible surface-to-volume ratio?

I am looking for the closest known approximate solution to Kelvin foams problem that would obey a spherical symmetry. One alternative way of formulating it: I am looking for an equivalent of Weaire–...
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