Usually people get mad because we close things too quickly without considering whether they are really on topic or not. But What are the next generation physics experiments? has been open for 2 days and only has 2 close votes, despite being the very definition of too broad.

Am I missing something on why this hasn't been closed yet, either by the community or by moderators? I'm really surprised that it hasn't been closed yet.

  • 1
    $\begingroup$ This was just being discussed in the chat room too. $\endgroup$
    – user10851
    Commented Apr 20, 2016 at 16:04
  • $\begingroup$ The review has been completed with 3 Leave Open: 1 Close vote. $\endgroup$
    – ACuriousMind Mod
    Commented Apr 20, 2016 at 16:05
  • $\begingroup$ How on Earth did this get 3 leave opens... I don't get it. $\endgroup$
    – tpg2114
    Commented Apr 20, 2016 at 16:13
  • $\begingroup$ @tpg2114 shouldn't someone comment in the other post with a link to this one? $\endgroup$ Commented Apr 20, 2016 at 16:20
  • $\begingroup$ @AccidentalFourierTransform Potentially, but since 3 people decided to leave it open, it's possible I just missed something or the community wants to have/see a shift in the scope of the site. I don't want to flame a post overtly (especially given the Hot Network presence it has for it's lifetime). I'd rather figure out if I am wrong -- I'm not trying to champion a cause over it. $\endgroup$
    – tpg2114
    Commented Apr 20, 2016 at 16:22
  • $\begingroup$ @ACuriousMind - your link has the URL inserted twice over. Just pointing out. :) $\endgroup$
    – 299792458
    Commented Apr 20, 2016 at 17:07
  • $\begingroup$ I think the explanation is that (at least three) people like it; they want to have this question here. One could complain that this is voting against policy, but that seems recently to have become acceptable here, and the new paradigm is that site policy will be set according to the whims of the reviewers. (I have had a couple of conversations with mods recently about people voting against policy and was surprised to get the response "it's supposed to be like that". Well, it isn't actually, and it's a terrible thing that we're letting it slide, but I think it's the explanation here as well.) $\endgroup$
    – N. Virgo
    Commented Apr 21, 2016 at 4:29
  • $\begingroup$ @Nathaniel Coming from an American (and hence English) common law background, I'm cool with the jury (close voters) determining policy (laws) even if they are against what the moderators (executive) and "legislature" (active Meta participants) decide as policy. That is all okay for me. But somehow I feel like I really missed the memo on this kind of question. I really thought it was so far off-topic that there was no question about it, no gray area, no subjectivity. This post was more about if I completely misjudged the community than if the question was/is off-topic. $\endgroup$
    – tpg2114
    Commented Apr 21, 2016 at 6:14
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    $\begingroup$ The question is well and truly in Too Broad territory, but to be fair, it has some very high quality answers. $\endgroup$ Commented Apr 21, 2016 at 11:19

2 Answers 2


This is how I read the question, which is admittedly a bit more concrete than the question text:

What are huge experiments which are going to run in the future and are currently under development (which means that at least part of the funding is already secured and people start building something). By "huge experiments" I mean experiments of the LHC,LIGO type, which means that a) thousands of people of all continents are involved and spend or will spend a majority of their time on the project and b) the experiment really is one big experiment (such as one telescope, one detector, etc.) and not a very tightly connected net of smaller experiments.

As such, it is a big-list question and, as you state, in principle off-topic. I don't think this is a reason to "close as off-topic", because it's just a general "big lists are off-topic". We should have a look at why big lists are off-topic. The best (?) reasons I could find are summarised by DavidZ: Why exactly are big-list questions discouraged? Shouldn't the FAQ say this prominently?

List questions are junk food for the site, in a way; they tend to be popular and attract a lot of attention, but they don't provide a basis for judging the correctness of answers (so the voting system is wasted on them) and they never really end, thus drawing attention away from other, better questions.

I would argue that these reasons are invalid for this particular question and that this particular question fits into the framework. Here are my reasons:

  • The question (as stated above) is precise, i.e. there is an objective way of judging the correctness of the answer: Is the experiment truly huge? Is it a physics experiment trying to explore physical concepts (on this ground, ITER might not really be a physics experiment) Is it past the initial exploration phase and under development? Is the experiment anticipated by parts of the physics community? This means that it is not overly opinion-based either.

  • The question is sufficiently focused. Indeed, I would argue that it is not too broad per se: the number of experiments that fits the bill won't be too huge. I bet there are less than twenty experiments.

  • The Stack Exchange framework does allow for a number of good answers and can, in principle, support small lists (I'm not so sure about lists like on mathoverflow with dozens of pages) and it is particularly good for questions where maybe not one person has the complete answer, but a complete picture emerges from several good answers.

  • While the question might not really "end", activity is very restricted. Only every few years will there be new experiments that fit the bill. Also, by the nature of the question, even without additions it will stay up-to-date for several years, if not a decade. For me, this is stable enough (who knows what happens with Stack Exchange in ten years?).

  • The question is interesting to researchers and enthusiasts alike. Hardly anyone knows all of these experiments, but many like to know whats going on outside their fields at least a bit.

There are two points that might be problematic:

  • In a sense, this gives a lot of reputation for easy answers, because of the popularity of the question. To counteract this, one might impose a similar rule as on mathoverflow, where all answers are immediately community-wiki. Then again, almost everybody gets their reputation from easy answers, so maybe this is not a real problem.

  • Clearly, the question garners a lot of attention. Maybe it draws away attention from better questions. I do not have a good counterargument other than that I feel this is true for almost all hot network questions, whether they are on-topic or not. Often, the physical content is even less than one can learn from the answers to this question.

In summary: I think that this is one of the very rare instances where such a list-based question should actually be on-topic for this site and I argued that the reasoning behind the close-policies allow for such a question to be off-topic.

  • $\begingroup$ A word on scale. A hundred people isn't big. Essentially every experiment that runs in JLAB's Hall C has at least 100 collaborators, and you can get away with simpler organizational principle until between 200 and 400 people by which time it becomes imperative to institute an additional layer of hierarchy. Then another one between 1000 and 2000 people (though I've never worked on a project of that scale personally). $\endgroup$ Commented Apr 20, 2016 at 20:02
  • $\begingroup$ You certainly read way more details into it than I did (or than I think the question contains). Which could arguably justify closing it as unclear, rather than too broad, since we seem to have reached really different ideas about the scope of it. $\endgroup$
    – tpg2114
    Commented Apr 20, 2016 at 20:29
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    $\begingroup$ @dmckee: Yes, I was actually thinking to say "thousands", but I didn't know the approximate numbers for many experiments - and I have no idea whether all these people work more or less full time on it or have a number of experiments they are on at the same time... I'll change it, nevertheless. $\endgroup$
    – Martin
    Commented Apr 20, 2016 at 21:48
  • $\begingroup$ @tpg2114: I agree that it's somewhat unclear - that is why I pinpointed exactly how I think the question can be read so that one can argue for "on-topic". I basically took the first sentence of the question to mean: I want a list of experiments of the scope comparable to the LHC or maybe a somewhat smaller LIGO. I tried to pinpoint what that means but you are definitely right that this should have been done in the question. $\endgroup$
    – Martin
    Commented Apr 20, 2016 at 21:55

I can offer the moderator perspective (well, at least my own): when I last looked at it, it had zero close votes, and I didn't feel like it was obviously enough off topic to close it unilaterally.

  • $\begingroup$ I'm curious for what reasons you thought it was on-topic -- I see a lot of borderline questions, but I thought this was incredibly clear cut. I'm open to being wrong on my interpretation of it if I missed, or misinterpreted, something. $\endgroup$
    – tpg2114
    Commented Apr 20, 2016 at 16:18
  • $\begingroup$ what's your opinion now that it has several close votes? $\endgroup$ Commented Apr 20, 2016 at 16:18
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    $\begingroup$ @tpg2114 I didn't think it was on topic. I mean, I personally thought it was clearly not appropriate, and if I were the site's dictator I would have closed it ;-) My logic was as follows: if I was right about it being clearly off topic, other community members would have stepped up with their own close votes, whereas if I was wrong, then it would have been an inappropriate use of moderator power to close the question. Evidently the latter is the case. Don't ask me why people think that way, but they do. $\endgroup$
    – David Z
    Commented Apr 20, 2016 at 17:00
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    $\begingroup$ I guess there is the fact that, other than being too broad and possibly not a good fit for the SE model, it's a pretty decent question. Personally I would say that makes it a good question for some other website, not for us - but in any case that does also make me reluctant to unilaterally close it. Given its current level of popularity, and the fact that it's been reviewed for closure and people voted to leave it open, I probably wouldn't vote to close at this point unless I was the 5th voter. $\endgroup$
    – David Z
    Commented Apr 20, 2016 at 17:04
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    $\begingroup$ @DavidZ it has 4 close votes now $\endgroup$
    – 410 gone
    Commented Apr 21, 2016 at 3:40

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