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?
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.
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.
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.
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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.
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.
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."
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.
