Talk:Indistinguishable particles
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"Symmetry Operator"
editSection "Exchange Symmetry" under "Quantum Mechanical Description of Identical Particles" says of an operator "Because it is unitary, it can be regarded as a symmetry operator," where the phrase "symmetry operator" is linked to the Wikipedia article Symmetry (physics).
The linked wiki page does not use the phrase "symmetry operator." Would someone please change the wording or define the term for non-expert readers? (Sorry, @CYD:!)
Identical vs Indistinguishable
editI think it is not nice to use identical and indistinguishable as synonym as it is done in the introduction and title. In a Boltzmann description the particles are identical but certainly distinguishable by their trajectory (this is formulated nicely in the first paragraph). — Preceding unsigned comment added by 2A02:1205:500A:DD40:61AB:D719:E302:3339 (talk) 09:05, 17 August 2019 (UTC)
- I agree. See next topic. Johnjbarton (talk) 03:19, 4 January 2024 (UTC)
Proposal to move this article to Indistinguishable particles
editMost of the descriptions I have read start a discussion of a system containing "identical particles" and proceed to show that QM predicts "indistinguishable particles". That is, we start with 5 unlabeled electrons, throw them in the QM machinery and discover that they have special properties: they are "indistinguishable".
For example Whittaker v2 p306: "Heisenberg and Dirac now investigated the general quantum mechanical theory of a system containing several identical particles, eg electrons. If the positions of two of the electrons are interchanged, the new state of the atom is physically indistinguishable from the original one."
The Gottfried, Kurt reference in the article says: "Their papers were the first to recognize that indistinguishability has profound consequences in quantum mechanics that have no counterpart whatsoever in classical physics."
I don't think that "identical" and "indistinguishable" are truly synonyms in English. "Identical" implies a kind of theoretical or mathematical equivalence; "indistinguishable" implies an operational difference.
If we consider classical theory with "identical particles" we will always be able to "distinguish" the states by trajectory. But in quantum theory with "identical particles", these particles will be "indistinguishable".
Since I believe this article intends to discuss the unusual issue in QM of indistinguishability, the title should be changed accordingly. Johnjbarton (talk) 03:21, 4 January 2024 (UTC)
- Identical particles are used sometimes in statistical physics. In this sense, it leads to interesting effects like Gibbs paradox. Note that this identicability is not the same as the quantum one. I support this move for clarity.--ReyHahn (talk) 09:40, 4 January 2024 (UTC)
- @ReyHahn Perhaps we should:
- Move this content to indistinguishable particles
- Change this article to overview, summarize Gibbs and indistinguishable particles.
- Johnjbarton (talk) 17:43, 7 January 2024 (UTC)
- Ok step one is done. Johnjbarton (talk) 18:32, 7 January 2024 (UTC)
- @ReyHahn Perhaps we should:
Exchange interaction
editWe have exchange interaction which is not linked in this article.
I added a section to exchange interaction based on Griffiths and some other refs. IMHO is better than most of what is in this article :-( Johnjbarton (talk) 03:03, 17 February 2024 (UTC)