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### Why isn't temperature measured in Joules?

If we set the Boltzmann constant to $1$, then entropy would just be $\ln \Omega$, temperature would be measured in $\text{joules}$ ($\,\text{J}\,$), and average kinetic energy would be an integer ...
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### What is the proof that the universal constants ($G$, $\hbar$, $\ldots$) are really constant in time and space?

Cavendish measured the gravitation constant $G$, but actually he measured that constant on the Earth. What’s the proof that the value of the gravitation constant if measured on Neptune would remain ...
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### What is the definition of temperature, once and for all? [duplicate]

Can someone please explain to me what the formal definition of temperature is? Neither my textbook, nor my professor, nor any of the online sources I've checked are able to give me a proper ...
3k views

### Can negative absolute temperature be achieved?

Thermodynamics does not allow the attainment of the absolute zero of temperature. Is then the term "negative temperature" a misnomer?
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### Is there a fundamental reason why gravitational mass is the same as inertial mass?

The principle of equivalence - that, locally, you can't distinguish between a uniform gravitational field and a non-inertial frame accelerating in the sense opposite to the gravitational field - is ...
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### Why is there a constant in the ideal gas law?

Why do we have constants? Consider, for example, the ideal gas law, $$PV = nRT \, . \tag{ideal gas law}$$ Sometimes I believe that the constant is there in order to make the equation work (make the ...
3k views

### Significance of the the Lagrange multipliers in statistical mechanics

In classic thermodynamics one can derive the Maxwell Boltzmann statistics by solving a Lagrange multipliers equation. In this process a new parameter $\beta$ is introduced to take account of the total ...
651 views

### Problems with units of entropy in statistical thermodynamics

The statistical thermodynamics definition of entropy: $S = kN \ln (W)$ troubles me a lot with the problem of dimenstions. where $S$ is entropy; $k$, the Boltzmann constant; $N$ the number of particles ...
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### Entropy and intuition about it's units

Trying to grasp Entropy not from the combinatorics point of view (I understand the micro-macro states thing pretty good now), but from the phenomenological point of view. So Entropy is: What ...
743 views

### How do we define temperature?

I was watching this video What is Temperature?. It states that when we measure temperature we are measuring $dU\over dS$ at equilibrium. But at equilibrium, how the entropy and the internal energy are ...
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### entropy for just one electron

Can we talk about the entropy for just one electron, such as the electron in hydrogen atom by the famous Boltzmann's formula? $$S=k_B\ln\Omega$$ I guess the answer is OK. But in thermodynamics, ...
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### How can temperature be defined as it is if entropy isn't a function of energy?

I've been taught that for large systems, the temperature of a system is defined as $$\frac{1}{T} \equiv \left(\frac{\partial S}{\partial U}\right)_{N, V}.$$ I have a problem with this definition, ...
### Is Boltzmann constant $k_B$ constant?
I heard in a lecture that Boltzmann constant $k_B$ is not constant in some special cases. Do you know the title of the article which contains this one? Do you think this idea is true?