Statistical mechanics and macrostates

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Discussion Overview

The discussion revolves around the concept of macrostates in statistical mechanics, particularly in the context of a system of atoms in a box divided by a partition. Participants explore the relationship between the number of atoms and the number of macrostates, as well as the implications of particle identity and statistics on this relationship.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant claims that for n atoms in a box, there are n + 1 macrostates, citing examples with 4 and 8 atoms.
  • Another participant questions the statistics involved, suggesting that if the atoms are identical, different statistical mechanics apply (Maxwell-Boltzmann, Fermi-Dirac, Bose-Einstein).
  • A participant clarifies that if the macrostate is defined as the number of atoms on one side of the box, the assertion about macrostates holds true.
  • There is a repeated inquiry about the number of macrostates if the particles are photons, indicating a potential distinction based on particle type.
  • One participant emphasizes that the type of particles (billiard balls, fermions, bosons) affects the discussion of macrostates.

Areas of Agreement / Disagreement

Participants express differing views on the implications of particle identity and statistics on the number of macrostates, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

There are limitations regarding the assumptions made about particle identity and the definitions of macrostates, which are not fully explored in the discussion.

Nylex
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In my Statistical Physics and Entropy module, we did something about atoms in a box with an imaginary partition down the middle, so atoms could either be on the left or the right. If there were 4 atoms in the box, the system would have 5 macrostates. If there were 8, there would be 9.

Is is true that for n atoms in such a box, there are n + 1 macrostates, for any n?

Thanks.
 
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Wrt what statistics...?If those atoms are identical,then u'd have 3 possible cases:Maxwell-Boltzmann statistics,Fermi-Dirac and Bose-Einstein.

If they're not identical,then it wouldn't matter what classical/quantum description u adopt...

Either way,a macrostate would be described through a n-tuplet (1,2,...,n) for distinguishable particles or (1,1,...,1) for indistinguishable particles.

Daniel.
 
If your macrostate is defined as the number of atoms in the left side of the box, then yes, since you can have 0,1,2,..., or n atoms on the left.
 
dextercioby said:
Wrt what statistics...?If those atoms are identical,then u'd have 3 possible cases:Maxwell-Boltzmann statistics,Fermi-Dirac and Bose-Einstein.

If they're not identical,then it wouldn't matter what classical/quantum description u adopt...

Either way,a macrostate would be described through a n-tuplet (1,2,...,n) for distinguishable particles or (1,1,...,1) for indistinguishable particles.

Daniel.

As usual, I have no idea what you mean.

Galileo said:
If your macrostate is defined as the number of atoms in the left side of the box, then yes, since you can have 0,1,2,..., or n atoms on the left.

Thanks.
 
If those 4 particles are photons,how many macrostates do you have there...?

Daniel.
 
dextercioby said:
If those 4 particles are photons,how many macrostates do you have there...?

Daniel.

:confused:
 
It was the easiest example to what i'd been trying to tell...It matters what kind of particles you have there...It's not the same thing if they're billiard balls,fermions or bosons...:wink:

Daniel.
 

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