Probability distributions for Maxwell-Boltzmann, B-E, F-D

In summary, Maxwell-Boltzmann distribution describes the statistical distribution of particle speeds in an ideal gas at thermal equilibrium, applicable to distinguishable particles. Bose-Einstein (B-E) distribution applies to indistinguishable bosons, predicting phenomena like superfluidity and Bose-Einstein condensation, where multiple particles occupy the same quantum state. Fermi-Dirac (F-D) distribution is for indistinguishable fermions, adhering to the Pauli exclusion principle, which governs the behavior of electrons in metals and leads to the formation of electron shells in atoms. Each distribution highlights unique statistical behaviors based on particle type and quantum mechanical principles.
  • #1
george743
1
0
Homework Statement
From Arfken Math Methods, chapter 23 (prob and stats), problem 23.1.6:

Determine directly or by mathematical induction the probability of a distribution of N (Maxwell-Boltzmann) particles in k boxes with $N_1$ in Box 1, $N_2$ in Box 2, . . . , $N_k$ in the kth box for any numbers $N_j$ ≥ 1 with $N_1$ + $N_2$ + · · · + $N_k$ = N , k < N . Repeat this for Fermi-Dirac and Bose-Einstein particles.
Relevant Equations
N/A
I don't even understand what question is being posed here. The answers given by the author are as follows:

Screenshot 2024-07-06 at 12.52.30.png


These are numbers, potentially very large ones.
 
Physics news on Phys.org
  • #2
george743 said:
Homework Statement: From Arfken Math Methods, chapter 23 (prob and stats), problem 23.1.6:

Determine directly or by mathematical induction the probability of a distribution of N (Maxwell-Boltzmann) particles in k boxes with $N_1$ in Box 1, $N_2$ in Box 2, . . . , $N_k$ in the kth box for any numbers $N_j$ ≥ 1 with $N_1$ + $N_2$ + · · · + $N_k$ = N , k < N . Repeat this for Fermi-Dirac and Bose-Einstein particles.
Relevant Equations: N/A

I don't even understand what question is being posed here. The answers given by the author are as follows:

View attachment 347872

These are numbers, potentially very large ones.
The answer definitely doesn't give probabilities.

To me it looks like the number of possible arrangements for distinguishable particles at the top and then indistinguishable fermions and bosons.
 
  • #3
george743 said:
Homework Statement: From Arfken Math Methods, chapter 23 (prob and stats), problem 23.1.6:

Determine directly or by mathematical induction the probability of a distribution of N (Maxwell-Boltzmann) particles in k boxes with $N_1$ in Box 1, $N_2$ in Box 2, . . . , $N_k$ in the kth box for any numbers $N_j$ ≥ 1 with $N_1$ + $N_2$ + · · · + $N_k$ = N , k < N . Repeat this for Fermi-Dirac and Bose-Einstein particles.
Relevant Equations: N/A

I don't even understand what question is being posed here. The answers given by the author are as follows:

View attachment 347872

These are numbers, potentially very large ones.
There's a lot that's strange here.

k < N is not possible for fermions.

The answer for BE is problematic if k < Ni.

The first answer simplifies to kN, which is the total number of arrangements of N distinguishable particles among k boxes.

My impression is that the question is about how many ways there are to place N1
particles in box 1 etc.. This is not really a probability, but it's proportional to one.

For indistinguishable particles I would say there is always only one way.
For example if you have 2 boxes and 5 bosons there is only one way to put 3 particles in box 1 and 2 in box 2. The answer given doesn't make sense to me. Maybe they're not asking about that after all.
 
Last edited:

FAQ: Probability distributions for Maxwell-Boltzmann, B-E, F-D

What is the Maxwell-Boltzmann distribution?

The Maxwell-Boltzmann distribution describes the distribution of speeds of particles in a gas that is in thermal equilibrium. It is applicable to classical particles that do not obey quantum statistics, and it is characterized by the temperature of the gas and the mass of the particles. The distribution shows that most particles have speeds around a certain value, with fewer particles at very low or very high speeds.

What are Bose-Einstein and Fermi-Dirac distributions?

Bose-Einstein (B-E) distribution describes the statistical distribution of indistinguishable particles that do not obey the Pauli exclusion principle, known as bosons. This distribution allows for multiple particles to occupy the same quantum state. In contrast, the Fermi-Dirac (F-D) distribution applies to fermions, which are particles that obey the Pauli exclusion principle, meaning no two fermions can occupy the same quantum state. Both distributions are essential for understanding quantum statistical mechanics.

How do Maxwell-Boltzmann, Bose-Einstein, and Fermi-Dirac distributions differ?

The primary difference between these distributions lies in the type of particles they describe and the statistical rules governing those particles. Maxwell-Boltzmann applies to classical particles that are distinguishable and do not exhibit quantum effects. Bose-Einstein applies to indistinguishable bosons, allowing multiple occupancy of quantum states. Fermi-Dirac applies to indistinguishable fermions, which cannot occupy the same state. These differences lead to distinct physical behaviors, especially at low temperatures.

In what scenarios are these distributions applicable?

The Maxwell-Boltzmann distribution is applicable in classical ideal gas scenarios at high temperatures and low densities, where quantum effects are negligible. The Bose-Einstein distribution is relevant in systems with low temperatures where bosons, such as photons or helium-4 atoms, can occupy the same quantum state, leading to phenomena like Bose-Einstein condensation. The Fermi-Dirac distribution is used in systems of fermions, such as electrons in metals, especially at low temperatures where quantum effects become significant.

Can you explain the significance of temperature in these distributions?

Temperature plays a crucial role in all three distributions. In the Maxwell-Boltzmann distribution, temperature affects the spread of particle speeds: as temperature increases, the average speed of particles also increases. For Bose-Einstein and Fermi-Dirac distributions, temperature determines the occupancy of energy states. At low temperatures, bosons can condense into the lowest energy state, while fermions fill energy levels up to the Fermi energy, with the distribution of particles changing significantly with temperature variations.

Back
Top