All Questions
Tagged with definition statistical-mechanics
86 questions
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How does one know that the entropy in the microcanonical ensemble is unique?
In my statistical mechanics course, we derived a form of entropy for the microcanonical ensemble. To do this, we imagined a system where there are two subsystems separated by a thermally conducting ...
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Locality in statistical field theory
In a lot of introductions to Landau-Ginzburg theory, which gives the partition function in the form of a functional integral $$\mathcal{Z}[F]=\int \mathcal{D}\phi e^{-\beta F(\phi)}$$
it is said that ...
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Definition of entropy and microstates (Huang)
The definition of Boltzmann entropy given in Ref. 1 appears to be different from most sources I've seen up to this moment. Let me start from the latter: typically textbooks assume that in a given ...
- 2,169
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Meaning of $n$-critical point
My lecture notes about field theory refer to a tricritical point as a point in which a continuous phase transition line meets a discontinuous phase transition line.
In the following it refers to a ...
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Clarifying the definition of pressure in statistical physics
I am studying David Tong's lecture note on statistical physics, and I have a question regarding the precise definition of pressure. I checked other postings in this community, but was unable to get ...
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Exact definition of entropy [duplicate]
Sometimes it is described as a state of disorder and sometimes it is called the inavalability of the thermal of energy of the system to do mechanical work.
So
How exactly is entropy defined?
Also, ...
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Is an entropy maximum being unique a tacit assumption in thermodynamics?
In Chapter 1 of his famous textbook on thermodynamics, Callen gives (among various other posulates) the following postulate:
Postulate II There exists a function ( called the entropy S) of the ...
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Difference between spontaneous and irreversible process?
I am confused about the difference between a spontaneous process and an irreversible process. Based on what I read so far, both processes increase universe's entropy. I never heard of any reversible ...
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What is the difference between Clausius' entropy and Boltzmann's?
We can only speak of entropy change, $dS$, when I mention Clausius as
$$dS=δQ/T$$
However, according to Boltzmann, entropy is defined as $S=K\ln\Omega$
My question is, is the $S$ according to ...
- 1,046
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Theory of physical causality?
There's a fairly well-developed tradition of "causal structure" in relativity theory and in relativistic quantum theory, which essentially determines which events in spacetime are "...
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Role of information in physics [duplicate]
The fact that information is preserved is often stated as a fundamental fact in physics.
Not being a physicist I do not understand how information enters physics at all. What is it an attribute of? ...
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Definition of the Ashkin-Teller model
There seems to be two different definitions of the so-called "Ashkin-Teller model", and I'm not sure which one is the one assumed by physicists (or which one is of more interest).
First, in ...
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What is the difference between an equation of state, and a state function?
Wikipedia seems to list them as two different things, (Equation of State, State Function); however, it seems like both pages are describing the same thing. Is there really any difference between the ...
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How is free energy defined for a single state?
In thermodynamics, in the canonical ensemble, it is said that the state of the system with the lowest free energy will be the equilibrium one.
However, I don't understand how we can defined the free ...
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What is the intuitive meaning of the typical value $e^{\left\langle \log X \right\rangle}$ of a random variable $X$?
The notion of the typical value $e^{\left\langle \log X \right\rangle}$ of a random variable $X$ comes up often in the study of disordered systems. For examples see the short paragraph above eq. (4) ...
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