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Applicability of quantum statistics and the essence of bosons and fermions

+ 1 like - 1 dislike
3592 views

There is a known tale for undergraduate students:

  • Each species of “particle” has spin, a.k.a. intrinsic angular momentum, a  quantitative property that is measured in .
  • Particles with an integer spin are called bosons, and with half-integer – half-integer – fermions. It’s all that exists in 3D.
  • Particles of the same species are indistinguishable (both bosons and fermions, but in a different fashion).
  • Bosons obey Bose–Einstein statistics, fermions obey Fermi–Dirac statistics, and both are instances of quantum particle statistics.

I, Incnis Mrsi, am a self-educated theoretical physicist. I read few textbooks and possibly there are some books that explain all these things correctly, not for children. When I took part in arranging all this stuff in English Wikipedia, I had to clarify some nuances.

First of all, has any “particle” certain intrinsic angular momentum? One can read my reasoning about it at https://en.wikipedia.org/wiki/Talk:Spin%E2%80%93statistics_theorem#The_spin_can_be_uncertain.2C_but_bosons_never_mix_with_fermions In short, it depend on exact definition of a “species” that often relies on a traditional nomenclature, not objective criteria. There is no essential difference, IMHO, between π/ρ, p++, and singlet/triplet O2 situations, but for subatomic particles physicists traditionally speak about different particles, whereas for atoms and molecules scientists traditionally speak about different states of the same object.

A related question is: to which extent is quantum statistics applicable to composite particles? I tried to answer with the https://en.wikipedia.org/w/index.php?title=Particle_statistics&diff=599715275&oldid=581345617 sequence of edits (a cumulative diff is shown).

The third subtopic is now split to a separate posting http://physicsoverflow.org//22129/crowding-of-bosons-and-the-density-of-bose-condensate

As it was suggested at http://physicsoverflow.org//21978/review-of-wiki-edits-or-articles%C2%A0-would-it-be-appropriate , I put the topic into the Q&A category. Note that I am now indifferent about the fate of Wikipedia articles, but I am willing to hear your criticism. Thoughts?

Closed as per community consensus as the post is not graduate-level upward physics
asked Aug 12, 2014 in Closed Questions by Incnis Mrsi (-15 points) [ revision history ]
recategorized Jun 21, 2015 by Dilaton

I think you'd post the third subtopic as a different question, as it (being a collective property of a huge number of particles) has nothing to do with the other two (that concern single elementary or composite particles).

Should I post it at this site, or go to the “undergrad” one?

From my point of view, posting here is fine.

As said here even if we agree that reviewing Wikipedia texts is on topic, the corresponding posts should still meet the level of PhysicsOverflow (graduate-level upward) and should be expressed clearly using the correct technical language as needed. This post seem rather undergrad-level to me. Voting to close.





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