Boltzmann Definition and 211 Threads

For context, this is when deriving the Boltzmann distribution by using a canonical ensemble (thermodynamics). omega is a function to represent number of microstates. According to wikipedia... is the first order expansion around 0 (Maclaurin series). My confusion: What are even...

New Scientist recently published an article entitled 'A Bold New Take on Quantum Theory'. I found interesting Unfortunately, it is behind a paywall, but I will give my precis. How QM, which only predicts probabilities, gives rise to the solid, well-defined world around us is still a mystery...

so I was studying H theorem from Richard Fitzpartic's site. https://farside.ph.utexas.edu/teaching/plasma/Plasma/node35.html Given H, they consider the following equation and set the constants as I want to understand how they got these particular values for a, b &c can we consider the...

LBM model for phase change- relevant equations found here. Also here. #Thermal LBM #solves 1D 1 phase phase-change #D2Q5 Lattice nx=100 # the number of nodes in x direction lattice direction ny=5 # the number of nodes in y...

In classical statistical physics, entropy can be defined either as Boltzmann entropy or Gibbs entropy. In quantum statistical physics we have von Neumann entropy, which is a quantum analog of Gibbs entropy. Is there a quantum analog of Boltzmann entropy?

Hi. I'm not sure where to put this question, thermodynamics or the quantum physics forum (or somewhere else). For a system in equillibrium with a heat bath at temperature T, the Boltzman distribution can be used. We have the probability of finding the system in state n is given by ##p_n =...

1.Does the Maxwell Boltzmann distribution change depending on the shape of the container? Pressure and the volume is constant. How is the Distribution affected whether the gas is in: a,sphere b,cube c,cuboid? Why does/doesn’t the distribution change depending on the shape of the container...

I (mechanical engineer) have researched this question but can't get to an answer. The equilibrium condition for confined particle diffusion of a solute in a solvent is reached when the solute spatial density is uniform (= zero density gradient), and entropy is max. But per Boltzmann, when...

Page 51 in <Moderator's note: link to copyrighted material removed, see instead http://dx.doi.org/10.1119/1.2967703> The image is showing functions: y1=e^(ln(n0)-x) y2=invDigamma(digamma(n0+1)-x)-1 where y2 is the "exact" version. How exactly is it exact? For this example (with 7 particles)...

In Lectures on Gas Theory (Dover Books on Physics) (p. 74), Boltzmann states “In nature, the tendency of transformations is always to go from less probable to more probable states”, by which he means what are now called macrostates. Thus he claims that an ideal gas almost always evolves to the...

Boltzmann entropy definition is given by: $$ S = k_B lnW $$ where ##W## is the weight of the configuration which has the maximum number of microstates. This equation is used everywhere in statistical thermodynamics and I saw it in the derivation of Gibbs entropy. However, I can't find the...

I was reading about thermodynamics postulates when i came over the differnetial fundamental equation: I understand that the second element is just pressure and last element is chemical energy, but he problem is i don't understand what is the use of entropy and how does it contribute to a...

Hello! Amateur question alert! Please excuse any misuse of terms. Answers gratefully received. :smile: I have a question about the energy that can be drawn from the vacuum through quantum fluctuations. My understanding is there are very strict limits on how much energy can be borrowed for how...

I (mechanical engineer) have researched this question but can't get to an answer. My question concerns the validity of the Boltzmann distribution. We start with "particles in a box". These particles (at t-zero) may exhibit a range of energies. We place this box of particles in a heat bath for...

I assume you people are all so preoccupied with all the hard sciencemastering going on that you're missing out on the more basic [sic] research abundantly present under the "Popular Physics" header at arxiv.org. Particularly: Futurama, Marvel's Supervillains and Boltzmann Brains. I'm not...

https://scholar.harvard.edu/files/schwartz/files/7-ensembles.pdf https://mcgreevy.physics.ucsd.edu/s12/lecture-notes/chapter06.pdf On page 3 of both the notes above, the author merely claims that $$P \propto \Omega_{\text{reservoir}}$$ But isn't $$P \propto...

Hello Can anyone explain what formula (or parameters) was used to create the exponential Boltzmann distribution in fig 2a of this document? http://image.sciencenet.cn/olddata/kexue.com.cn/upload/blog/file/2009/5/20095251352697121.pdf I figure it must be something like y=e^(ln(600)-b*x) for some b?

Hi. I've just come across something rather strange, I believe, about the micro-canonical derivation of the BE-distribution (as well as the Boltzmann and FD-distributions). See for example https://en.wikipedia.org/wiki/Bose%E2%80%93Einstein_statistics#Derivation_from_the_microcanonical_ensemble...

I am dealing with restricted Boltzmann machines to model distributuins in my final degree project and some question has come to my mind. A restricted Boltzmann machine with v visible binary neurons and h hidden neurons models a distribution in the following manner: ## f_i= e^{ \sum_k b[k]...

Context Boltzmann first defined his entropy as S = k log(W). This seems to be pretty consistently taught. However, the exact definitions of S & W seem to vary slightly. Some say S is the entropy of a macrostate, while others describe it as the entropy for the system. Where the definition of...

Hello, I was wondering if someone could show me how to determine the number of orbitals available for a state and the number of electrons in that state. For calcium in the ground state, the electron config is 1s2 2s2 2p6 3s2 3p6 4s2. For the first excited state I assumed 1s2... 4s1 3d1. From...

Hi With the exact Boltzmann distribution, ni = InverseDigamma(-α-β*εi)-1: https://studyres.com/doc/269738/revision-of-boltzmann-statistics-for-a-finite-number-of-p... Shouldn't I be able to get (n0, n1, n2, n3, n4, n5, n6, n7) = (6, 3, 2, 0, 0, 0, 0, 0) for some α and β, if N=11, E=7 and Δε=1...

Suppose you have an experiment of 2 possible outcomes 0 and 1 with probabilities p and 1-p respectively. I've been told in University that Restricted Boltzmann machines (RBM) can be used to infer probability distributions so I guess that one could built a RBM in order to infer p in the example...

I'm struggling with my Final Degree Project. I would like to perform a quantum simulation and perform quantum tomography for a single-qubit using a resrticted Boltzmann machine. In order to do so I'm trying to follow the recipe in the paper "Neural Network quantum state tomography, Giacomo...

Quantum mechanics is often said to be equivalent with Feynman path ensemble, which "after Wick rotation" becomes Boltzmann path ensemble, also called euclidean path integrals (popular for numerical calculations), or random walk/diffusion MERW (maximal entropy random walk). But Boltzmann path...

In the Aschcroft & Mermin solid state book there is a curve to compare F.D and M.B distribution. I can't understand the concept of M.B curve; what does mean exactlly when x =0? It means the probability of zero energy for particles is most or ...?

I was reading about the Debye-Huckle theory for electrolytes solutions (https://en.wikipedia.org/wiki/Debye–Hückel_theory). In all the books, notes, and in the wikipedia age too, there is this statement that troubles me: Shouldn't I have the "normalization factor" (i.e ##1/Z##) in the above...

Hi everyone, I am currently trying to work something out in regards to non-equilibrium thermodynamics. If I have a block of metal in vacuum that is being heated by a laser with a constant power P, is it even possible to be able to describe the emission of radiation by the block via the Stefan...

Let's look at the Boltzmann equation $$ \frac {p_{i}} {p_{j}} = e^{\frac{E_{j}-E_{i}} {kT}},$$ and take infinitely high temperature, the RHS becomes 1. I interpreted that this means every energy level is occupied by equal number of electrons. But if T is high enough, wouldn't the hydrogen atom...

When Boltzmann brains are mentioned in physics, they're often seen as a problem. An idea that is forbidden. Physicists like Sean Carroll actively tried to come up with new theories that avoid Boltzmann brains. Others like Leonard Susskind have also labled them as problems. Why is this, what's so...

I think this refutes the standard picture since if ylour universe would just keep expanding we should be a Boltzmann brain. https://en.wikipedia.org/wiki/Boltzmann_brain https://arxiv.org/pdf/0802.0233 I would bet on the "big rip" (dark energy getting stronger) since that would also resolve...

Hi, You could skip these details and find the main question at the bottom. I added the details for the sake completeness and context. Thanks. Boltzmann distribution of molecular speeds provides an insight into the different speeds the molecules of a gas are moving around with. It provides you...

I would like to see a derivation of the exact Maxwell-Boltzmann distribution shown as (16) in this document: https://www.researchgate.net/publication/222670999_Exact_Maxwell-Boltzmann_Bose-Einstein_and_Fermi-Dirac_Statistics This is my starting point (f being the function to maximize, g and h...

One thing that confuses me is the physical speed and sound speed. The lattice sound speed cs=1/sqrt{3} corresponds to the physical sound speed for isothermal flow (sqt{RT}). Why isn't the physical speed (e.g. inlet speed up of lid cavity) converted and use accoringly? $$c_p=\sqrt{RT}≈330m/s...

Hello, The relationship between entropy ##S##, the total number of particles ##N##, the total energy ##U(β)##, the partition function ##Z(β## and a yet to be defined constant ##β## is: $$S(\beta)=k_BN \cdot \ln(Z(\beta)) - \beta k_B \cdot U(\beta)$$ Which leads to: $$\frac{dS}{d\beta} =...

For a canonical ensemble the probability of occupying a certain microstate varies depending on the energy, however I thought that every microstate has an equal chance of being occupied. So what part of the canonical ensemble have I misunderstood?

Hello guys, i am currently studying for my msc thesis in theoretical physics and i need to find the derivation of relativistic Boltzmann equation, any suggestions ? Because i ve searched for papers/books for it and couldn't find anything. Any ideas? Thx in advance

Hi, I am working on a Boltzmann equation question and I know that the solution I am looking for is that: log(nij/nji)=log(gij/gji)-Eij(eV)(5040/T) The only thing I don't understand is why log(e-Eij/kt) = θ = 5040/T From what I have read in textbooks, it is just a given, but I really want to...

What justifies the use of multinomial coefficient in the combinatorics used by Boltzmann? The particles are distinct but counts as identical when they are in the same energy state?

Dear community, I am studying some equations related to the acceleration of cosmic rays(CRs) in magnetized plasma and I have seen a couple the equations I am not able to understand. First, I see that it is used as time-dependent Boltzmann equation for the CRs ∂ƒ/∂t + (vx + u)∂ƒ/∂x -...

Hi everyone, I have a few questions I'd like to ask regarding what I have read/heard about these two definitions of entropy. I also believe that I have some misconceptions about entropy and as such I'll write out what I know while asking the questions in the hope someone can correct me. Thanks...

Hello What is the meaning of the average velocity of gas molecules calculated by Boltzmann distribution (in kinetic theory of gases)? Does all molecules have the same average velocity?

Hello! I read today, in the context of DM, about the Boltzmann equation: $$L[f]=C[f]$$ where ##L[f]## is the Liouville operator (basically ##\frac{df}{dt}##), with ##f(x,v,t)## being the phase-space distribution of the system and ##C[f]## being the collision operator. I am a bit confused about...

When do we use the Boltzmann equation for density in a Fermi plasma? n in [cm-3] and when do we use the ρ=m/V, ρ in [Kg/m3 ] (this is not an example, I just added the equations to make my question more understandable) Is the ideal gas only when we have electron and ions? Is the Boltzmann...

‘Everything can happen, will happen’ so the saying goes. So given infinite time a universe is meant to generate infinite Boltzmann brains. But I was thinking about this: - Things that are possible can become impossible (example: heat death making Boltzmann brains formation impossible) -...

I was reading the derivation of Boltzmann distribution using the reservoir model. lets call the reservoir by index R and the tiny system by index A. In the derivation they proposed that the probability for being at energy e (for A) is proportional to the number of states in reservoir. I didn't...

In Vol III, 14-4 and 14-5 of the Feynman Lectures (http://www.feynmanlectures.caltech.edu/III_14.html), Feynman gives a discussion of the p-n junction, in which he derives the diode characteristic equation via a nice, simple and convincing application of the Boltzmann distribution to the...

Greg Bernhardt submitted a new PF Insights post Statistical Mechanics Part II: The Ideal Gas Continue reading the Original PF Insights Post.

Many textbooks claim that particles that obey Boltzmann statistics have to be indistinguishable in order to ensure an extensive expression for entropy. However, a first principle derivation using combinatorics gives the Boltzmann only for distinguishable and the Bose Einstein distribution for...