User talk:YohanN7/Archive 3

ANI
Someone mentioned a comment you made at ANI. Here is the required ANI notice:

There is currently a discussion at Administrators' noticeboard/Incidents regarding an issue with which you may have been involved. Thank you. Sławomir Biały (talk) 12:33, 2 July 2016 (UTC)


 * It took me a while to figure out exactly how I was involved and where. Since the matter seems to have calmed down, and I don't want to dive into the details of the matter, I'll simply retire with the observation that the (mis-) quote of mine offers good advice this time as well. The ANI is full of crackpots seeking some sort of cyberspace careers there, and anyone brought there will defend in any way possible, whether legal or illegal. The best thing to do is probably to first alert "project pages" (the appropriate ones to which the article in question belongs). That way the fight is fought on the home turf. I do understand, however, why you brought this to ANI. If this particular crackpot somehow escalates the matter, I'll see if I can contribute with anything more specific and more to the point. YohanN7 (talk) 14:44, 4 July 2016 (UTC)

Math reference desk
Hi, I quickly skimmed your post to the math reference desk; I can't reply there .. not allowed, but thought I'd give a quick reply here directly. In short -- some of the qft functionals can be made mathematically rigorous, but if requires a math background far exceeding that available to a typical physics PhD (and teaching it would add on another 5 years to the students time-in-class). Yes, the WP articles on QFT are mostly abysmal, and it will take huge amounts of work to fix them, and show when/where more rigorous approaches are possible. The latest research, though is quite interesting: here's one from the grand-master Alain Connes himself: http://arxiv.org/abs/hep-th/9912092 from which I quote: "This paper gives a complete selfcontained proof of our result announced in hep-th/9909126 showing that renormalization in quantum field theory is a special instance of a general mathematical procedure of extraction of finite values based on the Riemann-Hilbert problem. We shall first show that for any quantum field theory, the combinatorics of Feynman graphs gives rise to a Hopf algebra $\Hc$ which is commutative as an algebra....". Going back in time... one reason that supersymmetry initially got so exciting is that many variants were finite and required no renormaliztion. There was also a huge amount of interest getting a better grip on differential eqns in general, e.g. exactly solvable models, one poster-child of which was the Yang-Baxter equation .. which for example, describes the quantum deformations of the classical and affine Lie algebras (among other things). Another approach is the operator product expansion which avoids the problem of time-ordering of the quantum field operators by focusing solely on the operators for measureable quantities. So there's a huge amount of material here, its just so big its hard to grasp, and yes the WP articles in this area all need major improvements. 67.198.37.16 (talk) 14:22, 19 September 2016 (UTC)


 * Re-reading your post -- maybe I can provide a much much simpler answer. First, there is no prescription for taking some diff eq describing some symplectic geometry (the diff eq of classical mechanics) and replacing the p's and q's by operators to get a valid first-quantized operator eqn. One can almost get there, the first steps are studied under the name of prequantization or geometric quantization, e.g. the Moyal bracket. One can perform a second quantization of lagrangians, though, and this is covered in almost any book on QFT. The mathematical methods thread their way through the theory of the Fredholm alternative, and lead into e.g. the trace-class operators and the study of topological vector spaces. The compact topological vector spaces are the same thing as universal enveloping algebras, thanks to the Gelfand–Naimark theorem (see also Tannaka-Krein duality). The quantum deformation of these leads to the quantum groups, for example, the Weyl algebra is the quantum deformation of the symplectic form --again anything with the word "symplectic" in it is really about classical mechanics.  There are some marvelous books on classical mechanics that cover this: a very old but-still-modernish one is Abraham and Marsden from the 1970's. Another example are the clifford algebras which are deformations of the ordinary quadratic form aka metric tensor. Note that clifford algebras describe spin, which is why spin manifolds are studied.  Lets see. Then the rotation group describes rotations in 3D space. Its covered by the spin group, which is covered by the string group which is covered by the 5-brane group in the Postnikov tower. So there is a huge effort to convert those squonky QFT theories, and to take any arbitrary lagrangian or hamiltonian, or poisson bracket and quantize it.  Note that most possion brackets end up turning into Hopf algebras, which is why there's so much focus on that.  The other key insight is that supersymmetry is the local, gauged version of the exterior algebra.  Since the exterior algebra is central for solving differential equations, (by means of jet bundles, its not surprising that the locally gauged version of it is even more interesting....  67.198.37.16 (talk) 14:54, 19 September 2016 (UTC)


 * Thanks for your detailed reply, and I apologize for my late response (I have been taking a little break from Wikipedia). It will take me some time (probably plenty) to digest what you have written here. Some of the concepts I just barely know the definition (or statement) of. Thanks again! YohanN7 (talk) 07:59, 29 September 2016 (UTC)

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Note
You might be interested in my remarks in Talk:Minkowski space. — Preceding unsigned comment added by 92.26.14.17 (talk) 10:12, 21 October 2016 (UTC)
 * A further edit has now appeared. — Preceding unsigned comment added by 92.26.14.17 (talk) 10:25, 21 October 2016 (UTC)
 * Thanks. I have that page on my watchlist. YohanN7 (talk) 11:22, 21 October 2016 (UTC)

grammar point
Hi dear dude Could please tell me what's the difference between "have to" and "gonna have to"? thanks Alborzagros (talk) 11:06, 3 December 2016 (UTC)

My two cents on representations of the Lorentz group
Hi YohanN7,

I took a look at the article over the weekend. It's a nicely written article and very thorough! It easily passes B/B+ criteria in my opinion. You've done a lot of nice work it and your barnstar above is well-earned for this and the other group articles you have worked on.

But you asked for advice about how to get it to GA status and the feasibility of doing so. So I'll concentrate to gap between the current article and GA status. First, I'll say that for highly technical article like this is pretty rare and application of GA criteria is very dependent on the editor performing the review. So this is just my personal opinion. The points that came up in reading the article:


 * 1) The lead in a GA article is primarily a summary of the content of the article The current lead is mostly about why these reps are important, especially to physics. Probably the introductory/significance/applications material in the lead could be moved into a intro section of the article and the lead rewritten to be mostly a summary of the rest of the article.
 * 2) For highly technical articles, writing in clear prose accessible to a wide audience is an impossible task. Typically for GA articles, a compromise is made, per WP:TECHNICAL, in that the lead and intro sections should be "written one level down." I consider this graduate level stuff, so perhaps write the intro sections for an undergraduate. In this case that would a mean brief description what you mean by a rep (matrices in the finite dimensional case, basis functions in the infinite case) and a quick review of the Lorentz group (as rotations, boosts, space inversion and time reversal, etc) and algebra. This will give the causal reader some basic idea of what the article is about; that may be all they want.
 * 3) Where are the nonlinear reps? The answer may be Wigner's theorem.
 * 4) There is some inconsistency in the notation of the article from use of different fonts. For a lie algebra, mathfrak is used for displayed equations and in the text, either ordinary bolded letters or math bolded letters are used. It made me think as to whether these were are meant to be the same objects or not.
 * 5) There is a lot of good detail in this article, not only about Lorentz group reps,  but also Lie correspondence, CBH, relations to other groups, algebraic vs geometric POVs, etc. All good stuff, but a non expert might get lost in the details. What might help is (a) a brief description description of the plan of attack: first concentrate on the restricted Lorentz group, get at group reps from the algebra reps and the Lie correspondence, then add back in partiy and time reversal components, and (b) highlight the main result: a list of the Lorentz group reps. I guess that the Properties of the (m, n) representations section is closest to a main results section in the finite case.
 * 6) The Common representations section seems like it should be in the Lorentz Lie algebra section.
 * 7) With regard to citations, GA requires a certain citation density. For technical articles WP:SCICITE is often used. In practice that means definitely a citation in each section, and probably a cite in each nontrivial paragraph. The idea is not necessarily to verify controversial statements, but to show the reader where the material is drawn from. Against that custom, this article is pretty well referenced, but there are sections like the infinite dimensional history section that need more sourcing. E.g., who says that infinite reps were first studied in 1947?
 * 8) There are other GA criteria, such as making sure images are legal, described in WP:GACR

Well, sorry about all the apparent criticism. Just my two cents on what might be brought up during a GA review. Best, --Mark viking (talk) 20:55, 5 December 2016 (UTC)


 * Thank you Mark for your thorough review. I'll think about all items on your list. That only is going to take some time, and I really want to do some careful thinking before I comment on specific items. In the meanwhile, I also have some "legwork" to do on the article that doesn't require deep thought. It is now certain that I will go thorough with the nomination. The only question is when. Again, thank you very much for your input. Criticism is precisely what I wanted. Half barnstars are highly appreciated, tank you Cuzkatzimhut, encouraging (and were even decisive whether to go or not go), and good for the ego of an, at least yet, undeserving receiver, but not as useful as criticism. YohanN7 (talk) 10:51, 6 December 2016 (UTC)


 * @Mark viking, do you mind if I copy the above list to the article talk page when I comment (which is not quite yet)? It would also be practical in this case to allow for editing inside the list, providing proper indentation and use of signatures is used. (This is technically "writing inside someone else's post", but would be practical here if someone wants to chip in.) YohanN7 (talk) 08:20, 7 December 2016 (UTC)
 * Hi YohanN7, Sure, please feel free to copy it over and comment however you like. --Mark viking (talk) 09:56, 7 December 2016 (UTC)

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asymptotic particle state
thanks for clarifying this in S-matrix, but this is what I had in mind: A similar phrase appears in other contexts, Virtual_particle, Quantum field theory in curved spacetime

I was hoping the redlink could be a redirect to an anchor defining clearly what this is (perhaps somewhere in the article on scattering? "glossary of scattering".. "glossary of feynman diagram jargon")

Have you seen the 'hovercard feature'? it's nifty, giving users a definition hovering under the cursor. Eventually this will be extended to handle anchors

Any thoughts?

it should be trivially easy - you see a piece of jargon and if you dont get it, you either hover or click, you get a direct definition , right there (and the original author is free to use jargon without having to assume too much about what the reader does/doesn't know). I seem to run into a lot of friction with other users in trying to achieve this .. (objection to anchors, objection to trivially small articles, objection to adding a glossary page or small glossary section at the end) - very surprising

Fmadd (talk) 12:46, 11 February 2017 (UTC)


 * I'm in a hurry, and will reply properly later. YohanN7 (talk) 12:49, 11 February 2017 (UTC)


 * Okay, I see in part what you mean. But a red link is just that. A red link. These do not improve articles, and they do not have the effect of making people trip over themselves in eagerness to write a new article or whatever you intend. Hence I can also see where the friction you mention comes from. YohanN7 (talk) 09:23, 13 February 2017 (UTC)
 * So I see that glossary of particle physics redirects to glossary of string theory. would that be a good place to put a definition? Sounds to me like it's NOT specific to string theory. Another alternative would be to make a disambiguation page ... 'asymptotic particle state' can refer to:- <...>? then people can fill in the definition, and make a redirect. (it's a way of constructively "asking the community" for clarification.) Fmadd (talk) 11:39, 13 February 2017 (UTC)

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Spacetime Drive-by tagging
Only way to stop the "Son of Ref" tagger is to quickly add a bunch of references.

I've been working on them! No sweat. I think that I've located the primary sources for most of the later, poorly referenced sections. It seems to me that a bunch of guys who wanted to show off their "advanced" level of understanding looked up some graduate level texts and just added stuff randomly, not caring that most of the material that they added was totally irrelevant to the typical Wikipedia user.

Being a pack rat, I'm reluctant to section blank this stuff, despite its poor quality, until I've provided a good substitute.

I've been spending the last few weeks writing an Introduction section which I hope to be accessible to an intelligent high school student who is willing to put some effort into understanding the material. I've so far managed to limit myself to two (2) equations, preferring to substitute diagrams for math. The majority of the diagrams are mine, many newly created for this article.

Anyhow, leave the template alone. In a few weeks, I should have the article sufficiently referenced that I should be able to remove the tag and not be afraid of "Son of Ref" restoring it.

Thanks! Stigmatella aurantiaca (talk) 17:51, 13 April 2017 (UTC)


 * I've been enjoying myself with your article Representation theory of the Lorentz group. Not the whole article, just the prerequisites section. Face-smile.svg All of the material that you presented in this hidden section was thoroughly familiar to me once upon a time about 40 years ago, before I switched majors from physics to biology.
 * Anyhow, I've been considering adding a hidden Summary section to the Introduction section of the Spacetime article, sort of like your prerequisites section. What I am thinking about is something like this summary on the Spacetime "Talk" page. Unfortunately, the template doesn't work on mobile, and a non-hidden Summary section would be very detrimental to the user experience of somebody accessing the article on a phone.
 * Is there any precedent for creating an entirely separate Wikipedia article whose sole purpose is to be optionally wikilinked to?
 * If such a thing is allowed, then maybe I would title the article something like "Spacetime/Introduction Summary"? Then I could have something like this, which should work equally well on desktops and mobile:

Summary
Spacetime/Introduction Summary


 * What do you think? Stigmatella aurantiaca (talk) 05:05, 18 April 2017 (UTC)


 * I'll get back later and respond with more detail. But as far as the tag goes, it is no longer there. The point (at least my point) is that every article needs more citations, but no article needs the tag. Especially not "popular" ones. It is obvious to everyone. At any rate, this article had about 30 citations when I removed the tag (and about 40 now). This is well above the average for a C-class article. YohanN7 (talk) 07:19, 19 April 2017 (UTC)


 * I sort of hope in the future to develop a second section covering the Lorentz transformation to introduce the math of spacetime. In doing so, I want to stay as far away from the two-postulates approach as I possibly can. I may or may not want to follow Taylor and Wheeler as a model. I envision the second section as being non-calculus-based and accessible to a high school senior. A third section will introduce weak fields, and I don't see how to avoid calculus. I do, however, think that it should be possible to make the material accessible to a high school AP or freshman college science student. Stigmatella aurantiaca (talk) 20:21, 19 April 2017 (UTC)

Another possibility. The subheading itself should have the link.

Link to Spacetime/Introduction Summary
Stigmatella aurantiaca (talk) 22:59, 19 April 2017 (UTC)

Your GA nomination of Representation theory of the Lorentz group
Hi there, I'm pleased to inform you that I've begun reviewing the article Representation theory of the Lorentz group you nominated for GA-status according to the criteria. This process may take up to 7 days. Feel free to contact me with any questions or comments you might have during this period. Message delivered by Legobot, on behalf of SparklingPessimist -- SparklingPessimist (talk) 18:01, 21 April 2017 (UTC)

Your GA nomination of Representation theory of the Lorentz group
The article Representation theory of the Lorentz group you nominated as a good article has been placed on hold. The article is close to meeting the good article criteria, but there are some minor changes or clarifications needing to be addressed. If these are fixed within 7 days, the article will pass; otherwise it may fail. See Talk:Representation theory of the Lorentz group for things which need to be addressed. Message delivered by Legobot, on behalf of SparklingPessimist -- SparklingPessimist (talk) 16:20, 11 May 2017 (UTC)

GAN
It is possible that my wording in the current GAN was not unambiguous. I did not mean to say you plagiarize a text-book, but that the exposition is like in a textbook (concerning of the level of detail).

Since you were digging your heels into the Good Article Criteria, I cannot refrain from applying these criteria, applied to the current version of the article.

1a: ❌ (not free of spelling errors, the prose is often both verbose and lacking precision)

1b: ✅

2a-2d: ✅

3a: I am not an expert, from what I can tell though: ✅

3b: ❌ (fails badly)

4: ✅

5: ❌ [under the current changes]

6a-6b: ✅

7: ❌

Good luck with the article. Jakob.scholbach (talk) 18:02, 18 May 2017 (UTC)

Representation theory of the Lorentz group
Hi! Thank you for the work you have been doing on that page, I just wanted to make two suggestions:
 * 1) Lets change the in-line Lie algebra notation. Doesn't $$\mathfrak{sl}(2, \mathbf{C})$$ looks far better than $sl(2, C)$ for example? If you agree let me know and I will make the changes.
 * 2) The table in 3.3.2.2.1 needs to change. Why purple? Why bold?? One sees the diagonal there is no need to use boldface as a reminder! Also having the sums for $$m\neq n$$ in the same cell of the table as the $$(m,n)$$ representation strikes me as confusing. Let's have a table that only does $$(m,n)$$ pairs with an added row and column for $$\tfrac{3}{2}$$ and talk about the direct sums separately.

Latex-yow (talk) 20:01, 23 May 2017 (UTC)


 * Both excellent suggestions!


 * Some "history" about the inline notation: It used to be that PNG was default rendering, and inline Latex looked worse than awful, sometimes the size was double that of surrounding text and alignment was off. It was also the case that neither MathML nor MathJax could render all Latex in the article. Inline HTML math templates looks decent (but no more) on all devices. This has changed; now MathML is default, and some show-stopping bugs have been fixed.


 * Maybe the table could go up to 2? (Thinking gravitons here.) But this is not important, and would perhaps leave too many blank cells.


 * By the way, do you (or anyone) know which one corresponds to the adjoint representation? For the real (not complexified!) Lie algebra it is one of the irreducible ones since $$\mathfrak{so}(3, 1)$$ is simple (has no non-trivial ideals). It is not $$(1, 0) \oplus (0, 1)$$ as has been suggested, though this works out for the complexified Lie algebra. Counting dimensions, it has to be one of $$(\tfrac{5}{2}, 0)$$, $$(1, \tfrac{1}{2})$$, $$(\tfrac{1}{2}, 1)$$, or $$(0, \tfrac{5}{2})$$, but with any of these, there are other problems (funny spin content) when one looks at the restrictions to $$\mathfrak{so}(3)$$ of the adjoint action. I am honestly confused about this. YohanN7 (talk) 07:43, 24 May 2017 (UTC)


 * And oh, this belongs better on the article talk page than here. YohanN7 (talk) 12:05, 24 May 2017 (UTC)


 * Yes we should copy some of this conversation on the talk page. At any rate I have started no. 1 and redid the table into a plain looking one with added row and column for 3/2. Will add 2 right after this. As for your question I don't know the answer but I will try to look it up.


 * Thanks. There was an error (now corrected) in my candidates for the adjoint representation. The list is built by counting the dimension $(2m + 1)(2n + 1))$ of the candidates, which must be 6, the dimension of the Lie algebra itself. YohanN7 (talk) 07:07, 26 May 2017 (UTC)

Your GA nomination of Representation theory of the Lorentz group
The article Representation theory of the Lorentz group you nominated as a good article has passed ; see Talk:Representation theory of the Lorentz group for comments about the article. Well done! If the article has not already been on the main page as an "In the news" or "Did you know" item, you can nominate it to appear in Did you know. Message delivered by Legobot, on behalf of SparklingPessimist -- SparklingPessimist (talk) 14:02, 1 September 2017 (UTC)


 * Thank you YohanN7 (talk) 14:03, 1 September 2017 (UTC)

Incomplete DYK nomination
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DYK nomination of Representation theory of the Lorentz group
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DYK for Representation theory of the Lorentz group
Vanamonde (talk) 12:02, 25 September 2017 (UTC)