# Tag Info

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### Is thermodynamics only applicable to systems in equilibrium?

It entirely depends on what you think "thermodynamics" is. The traditional idea of thermodynamics dealing with systems whose macrostate can be fully described by e.g. temperature, pressure and volume ...
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### What is "Dynamical phase transition"?

Different people have different definitions of dynamical phase transition. At present, a widely accepted one is by Heyl et al. See their original paper Dynamical Quantum Phase Transitions in the ...
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### How is Newton's first law compatible with transport equations?

In order to have a (constant, non-zero) flux you need either no force at all or else a balance of forces. The situations ordinarily under discussion here are where there is either friction or a ...
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### Book recommendation for nonequilibrium thermo/stat mech

You may want to check 'Elements of Non-Equilibrium Statistical Mechanics' by V. Balakrishnan. The book does not cover too large a ground but focuses on the basic probabilistic tools of the subject. It ...

### What is the intuition behind the statement that non-equilibrium systems with static disorder are self-averaging?

I think the response by user kapaw is largely correct; I will try to simply expand on it in relation to the formalism. Indeed, the replica trick can be circumvented provided we ensure that the ...
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### Can Liouville's theorem describe the passage from nonequilibrium to equilibrium?

The fact that Liouville's Theorem appears to contradict the increase in entropy with time was one of the objections to the statistical mechanical definition of entropy when it was proposed by ...
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### Why turbulence is non-equilibrium?

I believe that indeed equilibrium/nonequilibrium here refers to thermal equilibrium/nonequilibrium. Informally, a system is in equilibrium if you leave it be and wait long enough, so that all currents ...
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### What happens to entropy when half the particles are removed?

Let the container be insulated and rigid, and let the initial entropy of the 2N particles be 2$S_0$. If a rigid partition is first inserted to separate the two sets of particles without letting the ...
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"most radiation described as black body radiation is in strongly non-equilibrium state, being a flux flowing from a hot object (such as a lamp filament or a star) to much colder surroundings"...
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Of your possibilities it is the second one that means that the blackbody approximation can be used in some cases. Ideal blackbodies are really hard to produce in nature because of the interface you ...
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### Equation of motion of a gas's center of mass due to heating

The natural convection problem you are envisioning can be solved for the time- and spatial variations of the temperature, the velocity, and density using the basic spatially differentiated transport ...
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### Is Fourier's law of conduction a consequence of the second principle?

When we speak about heat conduction we must use the laws of continuum thermomechanics, where quantities like temperature, internal energy, etc. can vary from place to place. The second law of ...
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### Non equilibrium statistical mechanics

There is no consistent and general formulation of non-equilibrium statistical mechanics because of three problems: (i) the lack of equilibrium constraints, (ii) irreversibility --the time-arrow ...
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### How to prove the Bose enhancement factor $(1+f)$ and the Pauli blocking factor $(1-f)$ in Boltzmann equation?
A proper derivation of the Boltzmann equation from non-equilibrium quantum field theory (which will give the factors $1\pm f$ in the weak coupling, quasi-particle dominated, limit) is a difficult ...