Linked Questions

37
votes
6answers
8k views

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 ...
37
votes
8answers
5k views

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 ...
27
votes
5answers
4k views

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 ...
15
votes
2answers
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?
22
votes
4answers
6k views

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 ...
8
votes
3answers
764 views

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 ...
3
votes
2answers
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 ...
3
votes
3answers
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 ...
6
votes
1answer
612 views

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 ...
4
votes
3answers
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 ...
3
votes
1answer
502 views

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, ...
2
votes
3answers
101 views

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, ...
1
vote
1answer
153 views

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?
3
votes
1answer
62 views

Regarding the Boltzmann entropy formula, is the Boltzmann constant really arbitrary?

In the top answer to this question (Is the Boltzmann constant really that important?) I read that the Boltzmann constant is just a dummy factor which converts energy to temperature. But that allows ...