This question :https://physics.stackexchange.com/questions/74639/boeing-747-crashes-into-a-solid-diamond-skyscraper was highly downvoted, and put on hold recently giving a reason "Primarily opinion based".

There were no comments whatsoever, as to why this was opinion based or to explain the down-votes. Is this kind of behavior appropriate on this site?

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    $\begingroup$ The automated close reason is for the purpose that users don't necessarily have to add comments :) $\endgroup$ – Waffle's Crazy Peanut Aug 20 '13 at 12:47
  • $\begingroup$ We have no idea about what kind of an object it is, etc. That's primarily opinhion based . $\endgroup$ – Abhimanyu Pallavi Sudhir Aug 20 '13 at 12:57
  • $\begingroup$ @Dimension10, You talk like you have experimentally determined string theory or any other theory in physics yourself(:p). Isn't physics about predicting what would happen with something new and not seen before?(It could be that you were kidding and I vented out my frustration on you just for no reason...) $\endgroup$ – udiboy1209 Aug 20 '13 at 13:36
  • $\begingroup$ @udiboy: Um, no I meant that the properties of the objects involved are completely unknown here. What are the properties of this aircraft, diamond, etc, , . , P.S. I deleted my answer to the angular momentum question. I realised I had misinterpreted it very differently and that everyone had misinterpreted my answer very differently . . . $\endgroup$ – Abhimanyu Pallavi Sudhir Aug 20 '13 at 14:12
  • $\begingroup$ I.e. I had thought that that question was asking for a spinning object attached to a rope and then the rope getting chopped ooff. $\endgroup$ – Abhimanyu Pallavi Sudhir Aug 20 '13 at 14:29
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    $\begingroup$ @udiboy this question is really morbid and may well hurt the feelings of people who have lost beloved ones because of some sad events some years ago. The physics contained in the question could have been asked without using this particular "real world example". Unfortunately there is no morbidity close reason and I hope morbid questions will not become so frequent that we need it ... $\endgroup$ – Dilaton Aug 20 '13 at 14:33
  • $\begingroup$ @Dimension10, you understood it correctly, angular momentum thing and the angular momentum still doesn't drop to 0. But this is not the place to discuss this. $\endgroup$ – udiboy1209 Aug 20 '13 at 17:00
  • $\begingroup$ @udiboy: I meant that if the rope is cut, the object, the thing which wass spinning around on the other side of the rope, that would fly away. That's what I meant by the angular momentum of the system is conserved. $\endgroup$ – Abhimanyu Pallavi Sudhir Aug 21 '13 at 1:56

I think what happened here is that the post was deemed "Not Constructive", and was closed with the "modern" analogue of that close reason, "primarily opinion based". POB doesn't apply as well as NC does here.

You may ask, "what's wrong with the post then"? Well, it's basically what's called an "idle curiosity" question -- you're not really aiming to learn something specific out of it, rather you're hoping to get some "accidental learning" from the post. It's not really focused.

That in itself isn't that much of a problem on this SE site1, however there's another issue: It's not specific enough. There's not enough information about the system to get a meaningful answer2 (alternatively, a good answer would require tons of analysis to get anywhere), which is sort of supported by this:

I've asked many Physics teachers and each has their own theory.

Once it doesn't have a definitive answer and it's not really focused towards a concept, it basically becomes a discussion. Such questions are great to discuss in person. You do indeed learn a lot by seeing the approaches of others. But the question itself doesn't really focus on any concept -- the learning value derives from the possibility of one of the answers teaching you a good concept. Coupled with it being discussiony, that makes it rather unsuitable for this site.

1. While most SE sites deal with "problems you actually face", the science sites don't (Well, not exactly), as explained here.

2. I suspect that supplying enough information to fix this would then just convert this to a homework/engineering problem.

  • $\begingroup$ Did we have the NC close reason before? Why was it removed? $\endgroup$ – udiboy1209 Aug 20 '13 at 17:01
  • $\begingroup$ @udiboy See blog.stackoverflow.com/2013/06/the-war-of-the-closes. In the new paradigm the option to use would be a freeform off topic. $\endgroup$ – Manishearth Aug 20 '13 at 17:14
  • $\begingroup$ It does say "make it clear exactly what needs to be fixed, or is problematic". Thats what I was obsessing about. $\endgroup$ – udiboy1209 Aug 20 '13 at 17:23
  • $\begingroup$ @udiboy I know. I agree that some helpful comments could have been left, too. Usually the close reason description is good enough (especially for homework and similar questions), but that need not always be the case. $\endgroup$ – Manishearth Aug 20 '13 at 17:50
  • $\begingroup$ If you don't have a precise answer does not mean, some one else cannot give one. If any answer is opinion based down vote it. Don't close the question because you can't see the answer yourself. The only place where there is some ambiguity is what is the nature of the plane. I did ask the OP to clarify it. $\endgroup$ – Prathyush Aug 21 '13 at 9:46
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    $\begingroup$ @Prathyush This has nothing to do with not having a personal answer -- I doubt it was closed because the CVers couldn't answer. A question that effectively invites opinion based answers should be closed, instead of waiting to pounce on the answers. There is ambiguity in the structure of the skyscraper as well. Structural engineering is a very complex field; we can't hand-wave it away. $\endgroup$ – Manishearth Aug 21 '13 at 11:56
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    $\begingroup$ "pure, solid diamond" to me is not ambiguous. There is no structural complexity, atleast that was the intention of OP. I believe he clarified it in the new revision of the question. $\endgroup$ – Prathyush Aug 21 '13 at 12:29
  • $\begingroup$ @Prathyush Hmm, alright then. I still think it's a broad engineering question, though :/ $\endgroup$ – Manishearth Aug 21 '13 at 12:47
  • $\begingroup$ It seems like the OP deleted the question, what a waste. $\endgroup$ – Prathyush Aug 21 '13 at 13:25

I'm going to start by commenting the word "appropriate" in the context of getting downvotes.

People sometimes seem to come to meta looking for a ruling that the crowd was wrong, but that is not how it works. We rely on the crowd to get things right.

Votes (up and down) are plenary: excepting vote fraud people are empowered to vote any way they like. Nor are down votes a bad thing: they are an integral part of the evaluation this site does on posted material.

Some people also seem to be of the opinion that downvotes are intrinsically rude. Well, I disagree: there are things in this world that are not any good at all; that fail to meet even lax and minimum standards for quality. A correct evaluation of them should conclude that they are bad. On Stack Exchange sites posts which don't meet a minimum standard should be downvoted. I'd go so far as to say that if you don't cast several percent of your votes as down (when you have the power), then you are not doing your part.

In this instance I suspect that the OP is being punished for either being insensitive or for sensationalism. In either case that is the privilege of the people doing the voting. Of course it is appropriate.

To the close reason, I don't like "Opinion based" for this very much because a correct answer could arrived out after much simulation using a large cluster or supercomputer and person months of specialized materials simulation physicist or engineers. On the other hand, no one has done that work so you are in practice inviting people to guess or to have a "conversation" on the topic.

I will not be reopening this question.

  • $\begingroup$ I didn't mean to emphasize on the down-votes particularly, although I usually leave a reason for down-voting(It says to do so when I down-vote). My question was about the close reason. I mean you could have left "a correct answer could arrived out after much simulation using a large cluster or supercomputer and person months of specialized materials simulation physicist or engineers." in the comments, and I wouldn't have said a thing after that. $\endgroup$ – udiboy1209 Aug 20 '13 at 16:53
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    $\begingroup$ @udiboy Fair enough. I wasn't involved in the decision to close the question and I'm not sure what reason I could have picked even though I don't like the question. I haven't downvoted either but that is because of a distaste for piling on (especially when the OP is a new user). $\endgroup$ – dmckee --- ex-moderator kitten Aug 20 '13 at 17:51
  • $\begingroup$ Huh. I didn't know I was supposed to vote depending on how strong feelings I have about something. $\endgroup$ – delete000 Aug 21 '13 at 6:33

I wasn't even aware of this situation when it happened, and I'm not sure how I personally would have voted/dealt with close votes, but consider this:

Our close reasons often overlap, and the "primarily opinion-based" consensus could probably have been phrased in terms of our engineering close reason:

This question appears to be about engineering, which is the application of scientific knowledge to construct a solution to solve a specific problem. As such, it is off topic for this site, which deals with the science, whether theoretical or experimental, of how the natural world works. For more information, see this meta post.

Problems where the solution depends on too many variables, or where the variables are not particularly constrained or even fully defined, are considered off-topic by association with engineering. The reason is, the correctness of any answer given depends sensitively on all sorts of extra information, much of it not necessarily related to any particular physics concept. For example, the scaling for how a beam deflects under a load may be a valid physics question, but a question that relies on the exact dimensions and material properties of some particular beam is not.

When the problem goes beyond universally-accepted underlying physical concepts, the only way to generate any solution at all is to make a number of assumptions. Thus engineering questions are generally also off-topic as opinion-based, simply by virtue of the fact that they ask a bunch of physicists/physics enthusiasts for their opinions to fill in the blanks.

As mentioned elsewhere, there were plenty of downvotes and surrounding controversy. I suspect the wording of the question was such as to amplify whatever response it was going to get anyway, and as I've explained above, the response was likely to be "this doesn't belong here" for one reason or another. This isn't to say that a little whimsy or an attempt to connect to current events/the Zeitgeist isn't allowed (I'm certainly guilty of titling questions so as to make them more attention grabbing), but understand that this method will amplify negative reactions as much as positive and so is inherently risky.


I will only address the closure, not the down votes in this meta answer.

I closed OP's question (v4) as primarily opinion based, not because there isn't a definite scientific answer that in principle could be reach, but because to reach a scientific sound conclusion would mean to perform a tremendous amount of rigorous analysis, which almost certainly does not exist in the literature, which would be too much work to lay on potential answerers, which would be technical rather than conceptional in nature, with a too1 localized scope, which cannot be easily generalized to other situations, to be interesting or enlightening to anyone.

Short of such scientific rigorous answers, the answers to this question will tend to be almost entirely based on opinions, as indicated in the reason for closure.


1 This does not imply that one is not allowed to ask difficult advanced research questions at Phys.SE that might take a lot of work to answer fully. But there should be a reasonable potential scientific or intellectual payoff, which is completely lacking in this case, cf. comment below by Nathaniel.

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    $\begingroup$ That's a terrible reason to close a question. Does this mean we can't ask advanced research questions here any more? The answers to those will not be found in the literature either. $\endgroup$ – Nathaniel Aug 20 '13 at 13:26
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    $\begingroup$ This should be mentioned in the comments while closing, or we should have this as another close reason, because "primarily opinion based" doesn't imply that. And I agree with @Natheniel. $\endgroup$ – udiboy1209 Aug 20 '13 at 13:37
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    $\begingroup$ @Nathaniel There should be a close reason for morbidity. This is what would have fitted the bill here exactly. In view of some very bad happenings some years ago, asking such a question could well hurt the feelings of some people. $\endgroup$ – Dilaton Aug 20 '13 at 14:28
  • $\begingroup$ @Dilaton I do agree with you, but that doesn't change the fact that this is a really bad reason for closing it. There's no justification for closing something because it's "too much work" for the answerers according to any policy document that I'm aware of, and the idea that no answer could be "enlightening to anyone" is a pre-emptive value judgement that makes no sense to me. If Qmechanic had said "well, really I closed it because it's a bit morbid, but there's no official close reason that applies to that" then I would have much less of a problem with it. $\endgroup$ – Nathaniel Aug 21 '13 at 0:07

I was the first downvoter on the question and I downvoted it now, again after the question was edited.

The reason for the downvote is that the poster seems to have no compassion to the relatives of those who perished 12 years ago.

Generally, I don't have to explain the reasoning behind my downvotes. But for this one, I think an exception is in order.

I will post this as a comment to the main question as well.

  • $\begingroup$ I think formulation could have made it less tasteless, but that wasn't the case here. $\endgroup$ – Bernhard Aug 22 '13 at 18:30

Given the assumptions, I believe the question is well posed. In the real engineering world, this type of calculation is frequently performed and simulated, and the results are far from "opinion based." It seems most people that are against this question are more inclined to theoretical physics / high level math. While I'm sure this question can have a highly-theoretical answer, it's most likely best answered as you answer "how much torque can I apply to this beam before it breaks." You answer it with having some material properties of the material (which were found by experimentation). A very good "engineering" way to answer the question would be to do pen-and-paper calculations using Mohr's circles and check to see if anything exceeds diamond's ultimate shear/tensile stresses (which should be straight-forward on a rectangular structure) and "check" the results by simulating it in a FEA program such as Catia, assuming you know the diamond properties and just model the plane crash as a impact force... and see what happens. I don't see how that result would be "opinion based."

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    $\begingroup$ I agree with the view posted here. $\endgroup$ – Prathyush Aug 21 '13 at 9:42

Given the sensitive nature of the question, I've decided that it is now beyond the point of repair. I made the mistake of including sensitive details, which were too closely linked with the events of the past.

Changing my question to make it less descriptive would simply ruin it's purpose. I have for those reasons decided to delete the question.

I stand corrected.


While I might not be capable of answering this question, the question itself has been extremely well posed, I think it should have a well defined answer.

I think the correct analysis of the stress required to fracture a material must be involved in some way. This question is not very different atleast conceptually from a slightly different question, "How much force do I need to apply on a diamond rod to break it?"

For these reasons I request reopening of the question.

However, I think that the OP must clarify what the mass of the plane is and so on.

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    $\begingroup$ I don't agree that the question is well-posed. What happens would depend greatly on the fine details of the building's design. Structural engineering with nano-scale diamond fabrication is not a well understood subject. Asking the people who hang out here to invent it to answer this dippy question is asking too much. $\endgroup$ – user1504 Aug 20 '13 at 20:55
  • $\begingroup$ @user1504 it says it is made of "pure, solid diamond". Would you say the same to the question "How much force do i need to apply to break a diamond rod?" $\endgroup$ – Prathyush Aug 21 '13 at 8:24
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    $\begingroup$ If it is literally made of pure solid diamond, it is not a building. $\endgroup$ – user1504 Aug 21 '13 at 11:16
  • $\begingroup$ @user1504 The OP claified that in the new revision of the question. $\endgroup$ – Prathyush Aug 21 '13 at 12:34

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