Let us take as an example this question. Consider whether you think it should be considered off-topic (for being purely mathematical in nature).

Should one's opinion on whether a mathematical question be closed be based on what one finds interesting, the specific written rules of this site, a combination, or something else entirely?

I do not think this question is trivially answered by referring to the site tour (see KyleKanos's comment below) because the tour says that what's allowed is

Mathematics in the context of physics

and states

Questions on mathematical details outside of physical context are off topic

The problem seems to be that there is enormous room for interpretation. A pure math question may have obvious physical implications even if the question doesn't explicitly reference those implications.

One approach is to take the question at face value and not allow for any benefit of the doubt with respect to implicit relevance to physics. With this approach, the example question linked above would be closed.

Another approach is to consider whether the mathematics in the question is directly relevant to physics or might simply be so common in physics settings that other users of the site would find it interesting and useful. From this perspective, the example question might be kept open.

  • $\begingroup$ If the down-voter would care to comment why this is a bad question I might stand to learn something. $\endgroup$
    – DanielSank
    Commented Oct 9, 2014 at 17:57
  • $\begingroup$ A good starting place would be here and here. Also useful is the privilege page for VTC $\endgroup$
    – Kyle Kanos
    Commented Oct 9, 2014 at 18:02
  • $\begingroup$ @KyleKanos: Indeed. I am trying to ask a more organic question, however. I am interested in how people actually decide their votes in practice. $\endgroup$
    – DanielSank
    Commented Oct 9, 2014 at 18:04
  • 1
    $\begingroup$ Now this doesn't really seem any different from DavidZ's post back in April $\endgroup$
    – Kyle Kanos
    Commented Oct 9, 2014 at 18:23
  • $\begingroup$ @KyleKanos: Quite similar. I'm trying to understand how the decision should be made, not what the written rules should be. The accepted answer to DavidZ's post says that questions devoid of physics should be moved to MathSE. However, this is not what happens as a matter of fact, so I'm trying to understand how people actually make this decision in reality. $\endgroup$
    – DanielSank
    Commented Oct 9, 2014 at 19:05
  • $\begingroup$ ...By looking at the questions (often times ones that have been flagged by someone else) and determining if it fits the criteria set out by the starting places I mentioned earlier. I'm not sure what more you are really trying to get at. $\endgroup$
    – Kyle Kanos
    Commented Oct 9, 2014 at 19:08
  • $\begingroup$ @KyleKanos: I'm not trying to "get at" anything more than to understand how people actually make this decision. I'm asking this because the sample of questions which are and aren't closed does not make sense to me yet. In other words, I haven't managed to identify the common pattern at work in practice. $\endgroup$
    – DanielSank
    Commented Oct 9, 2014 at 19:11
  • $\begingroup$ I don't believe that there is a common pattern, given that there's at least a dozen of us from varying backgrounds that vote on such questions. If you think a question is off-topic, feel free to flag it; that will bring it to the 3k+ review queue where we use our best judgment. $\endgroup$
    – Kyle Kanos
    Commented Oct 9, 2014 at 19:16

1 Answer 1


My procedure is the following when faced with a math question with no physical context given:

I am quite hesitant to migrate questions to math.SE and proceed in the following order:

  1. If the question is closeable under the homework policy here, I'll vote to close it as homework. People too lazy to read our policies before posting should not be given the convenience of migration to a site that will answer their question, since that does not discourage them from just posting here again next time.

  2. If I know the physical motivation for the question, I'll leave a comment asking the OP if that was their motivation, and not vote to close it. (In the question you cite, I didn't do that since the physical relevance of SU(N) representations is something I considered implicitly understood.) It would probably be best to make a habit of editing it in myself, but that would often change the original post considerably and thus be time-consuming.

  3. If I don't know the physical motivation, I'll vote for migration to math. (Sometimes leaving a comment asking the OP to add physical relevance)

Now, it is obvious that 2. and 3. depend on my personal knowledge (as most close votes do, at some point). But migrating away questions that I know to be connected to physics is just not the right thing to do, in my opinion. Nevertheless, we are told to judge questions as written, improve those we can, and close those we can't, so the cases in 3. must be voted to migrate by me even if there's some motivation behind them I cannot fathom.

It is important to remark that I don't consider this process to be any more subjective than other close votes, especially homework, where the spectrum from "lenient" to "harsh" close-voters is quite broad on this site.

  • 1
    $\begingroup$ +1 for answering the question so clearly. It's interesting that you say you vote for migration if you don't know the possible relevance to physics. Given that close/hold/migration occurs when a small number of users vote for it, this essentially means that a minority of people unfamiliar with possible applications of a mathematical technique or idea can cause closure of a question which might be of interest to many. This precludes extension of the site's scope to areas of physics less practiced by existing members. This is why I asked whether people vote out of personal interest or site law. $\endgroup$
    – DanielSank
    Commented Oct 9, 2014 at 23:53
  • $\begingroup$ @DanielSank: true, but how much effort is it for the OP to add a sentence indicating the motivation for the question? Compare with with the effort required to read the question and try to figure out its physical significance, if any (multiplied by five for the required five VTCs). $\endgroup$ Commented Oct 10, 2014 at 6:03
  • 1
    $\begingroup$ @JohnRennie: That sounds like an argument for not giving the OP the benefit of the doubt. Seems reasonable, but then see ACuriousMind's answer were he specifically says he does give the benefit of the doubt if he feels the math topic is relevant to physics topics he knows about. $\endgroup$
    – DanielSank
    Commented Oct 10, 2014 at 6:56
  • $\begingroup$ @DanielSank: and I feel much the same as ACuriousMind when I can see the physical motivation, but I'm an experimental scientist and don't have ACuriousMind's mathematical sophistication. The point is that if I can see no physical motivation and the OP hasn't provided one should I remain paralysed by doubt about my own inadequacies or should I VTC? $\endgroup$ Commented Oct 10, 2014 at 7:10
  • 1
    $\begingroup$ @JohnRennie: First of all, thank you for actually engaging me in this discussion. I don't know whether or not you should be paralyzed by doubt, but I do think the current system is messed up. Using your and ACuriousMind's approach, if a small number of people with voting privileges who aren't familiar enough with a mathematical topic to guess its relevance to physics view a question about that topic, the question gets canned. This seems backwards. Why should the ignorance of a small number of users be allowed to close a question which might be of interest to others? $\endgroup$
    – DanielSank
    Commented Oct 10, 2014 at 9:22
  • 1
    $\begingroup$ @JohnRennie: As an example, suppose there are 1000 users and 10 of them don't know what linear algebra is. Suppose someone asks a question about linear algebra which is of intense intereste to 990 users. The other 10 see that question and think "Hm, that doesn't sound like something I use in my physics work, so I vote to close." The question is canned, and unless someone makes a meta post that's the end of it. Doesn't that seem screwed up to you? $\endgroup$
    – DanielSank
    Commented Oct 10, 2014 at 9:24
  • 2
    $\begingroup$ @DanielSank: if the post started "I'm trying to use linear algebra to describe <insert physical system of your choice> ..." and it still got closed I'd agree, but how often do such questions get unfairly closed? I guess there will be occasions when the OP thinks it's obvious what the physical significance is and doesn't bother to mention it, and maybe the more mathematically sophicated site members will agree. However I maintain that if OPs don't make the effort to show some physical significance they can't complain if their questions get closed. It's their responsibility not ours. $\endgroup$ Commented Oct 10, 2014 at 9:56
  • $\begingroup$ @DanielSank: The review system is designed so that a minority will rarely close a question, since three leave open votes will remove a question from the queue, and the minority closers would then have to visit the question by themselves to vote to close (not that that's impossible, but it's less likely). $\endgroup$
    – ACuriousMind Mod
    Commented Oct 10, 2014 at 13:31
  • $\begingroup$ @DanielSank: this would be a good example. The Schechter function is used to describe luminosity in astronomy, but the OP has neglected to say so. If the question is closed as too mathy that's really the OP's fault. (Actually it's likely to be closed as homework :-) $\endgroup$ Commented Oct 10, 2014 at 15:27
  • $\begingroup$ @JohnRennie: I'm not arguing that mathy questions should be left open. My OP just asks how people make this decision because I'm trying to understand how the site works. It appears to me that whether a mathy question is left open or not is somewhat random, but depends a lot on whether the math topic is something that particle theorist like. That doesn't seem sensible to me so I'm just trying to understand what's going on. $\endgroup$
    – DanielSank
    Commented Oct 10, 2014 at 15:47
  • $\begingroup$ On point 2: if you have to ask the OP whether something was their motivation, then you don't know the physical motivation... $\endgroup$
    – David Z
    Commented Oct 11, 2014 at 19:15

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