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Recently, I was unable to perform a physical calculation correctly, and I could not find any explicit proof of it, not online or in any book, to understand what I was doing wrong.

This calculation involved more than a page of passages and when I asked about it, I asked for a source or an hint, but I didn't ask, for example, if someone that had done it in the past could post his/her result. I read the policy of the site, but I don't understand if a specific long and tedious proof is something that can be explicitly asked.

Thanks for any clarification on this.

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    $\begingroup$ Possibly related: Should any check-my-work questions be made on topic? $\endgroup$
    – Peter Mortensen
    Nov 5, 2022 at 18:48
  • $\begingroup$ @PeterMortensen Actually it's not exactly a check-my-work question, because I didn't post my faulty derivation: anyway the answer made by ACuriousMind in the question you linked seems to say I'm allowed to do so. I still don't want to do it, because I'm more interested in checking by myself a working calculation despite asking for what is wrong in mine. In any case, thanks for your interest. $\endgroup$
    – Rob Tan
    Nov 5, 2022 at 19:08
  • $\begingroup$ when I asked about it You really need a link to the question you asked. $\endgroup$
    – StephenG - Help Ukraine
    Nov 6, 2022 at 10:10
  • $\begingroup$ @StephenG-HelpUkraine physics.stackexchange.com/questions/734700/… I didn't want the attention on the specific question, just to understand if was possible to ask something like this if the question involves a result of physical relevance, in this case curvature variation under Weyl transformation. Thanks for your interest $\endgroup$
    – Rob Tan
    Nov 6, 2022 at 12:42
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    $\begingroup$ @RobTan "Actually" it is a check-my-work or homework-like question. You can not wiggle out of this on a technicality such as "I didn't post my faulty derivation." The question does not have to literally be homework or literally request checking of work. You need to approach this non-literally. You need to think about: would a reasonable person reasonably think that this question could or should be categorized as homework-like or check-my-work-like. $\endgroup$
    – hft
    Nov 11, 2022 at 20:52
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    $\begingroup$ @hft Yes I did, in fact I did not post my derivation, just the results and asked for the correct derivation. There is a lot of attention on the specific question, that I sincerely don't understand, and what I'm understanding is that certain physical questions, and I still don't grasp the criteria, just cannot be asked: is too complex. I value many advices here and constructive critics, but all seems just too much for a question about a calculation like many others in physics $\endgroup$
    – Rob Tan
    Nov 12, 2022 at 8:04

2 Answers 2

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The difficulty of this question as it currently stands is that it is of limited interest to anyone but yourself, i.e. it is of limited value to the site. In addition, it is severely lacking context (what is $n$).

Maybe there’s a way for you to turn this into some that has broader appeal. You could provide better context for one, provide multiple sources to confirm to confirm you are incorrect, and identify exactly where things go sideways. It would likely still be specialized and of the check-my-work type, but at least you will earn some good will by clearly identifying where conceptually you are diverging from the known solutions.

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    $\begingroup$ Thanks for your answer. Sorry but I disagree: the result for which I'm looking for a proof is used in the context of conformal transformations, that are a broad topic with many ramifications and that is analyzed in every text I saw about quantum field theory in curved spacetime. So, I can agree on the fact that not everyone is interested in proving how curvature changes under conformal transformation, but I can't agree on the fact that it is not of physical, but only on personal interest to prove it. $\endgroup$
    – Rob Tan
    Nov 7, 2022 at 8:49
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    $\begingroup$ In fact the result has consequences like imposing value to constant parameters of the theory depending on the spacetime dimension $n$: it doesn't affect me personally, that should be a concern of physics and so of everyone studying it. Also, I already tried what you suggest, but I can provide more sources attesting the result I have at the moment is wrong. Thanks again. $\endgroup$
    – Rob Tan
    Nov 7, 2022 at 8:57
  • $\begingroup$ @RobTan most of what you just said is context that should be in original question. If someone is interested in QFT in curved spacetime, they would be lucky to find your question. $\endgroup$
    – ZeroTheHero
    Nov 7, 2022 at 9:08
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    $\begingroup$ Say what you want about my criticism, you are the one trying to get people to answer your question, which unfortunately for you only has 35 views after 5 days. $\endgroup$
    – ZeroTheHero
    Nov 7, 2022 at 9:09
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    $\begingroup$ Maybe we are equivocating each other. I'm saying every question is personal, because it affects you personally and your will of knowledge; this doesn't mean that a question, that is personal, is only that and is not of physical interest. I'm not trying to force anyone to answer my question. I didn't even link it in the first place since that was not the intention: if the answer to what I asked here was affirmative I edited the question asking for a long proof and start a bounty. That's it. Thank you for answering. $\endgroup$
    – Rob Tan
    Nov 7, 2022 at 9:17
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    $\begingroup$ I’m not claiming your question has no physical interest, or that any question of the “proof” type you are discussing has no physical interest. Just that it needs to bring value to the site. This is harder to discern if you ask for a long proof about an overly specific problem or, contrariwise, is easier to discern if you are clear about the context. Your question (as an example) is not clear about context and thus likely to have difficulty in generating answers. That’s all. $\endgroup$
    – ZeroTheHero
    Nov 7, 2022 at 9:24
  • $\begingroup$ Ok thanks for the suggestion $\endgroup$
    – Rob Tan
    Nov 7, 2022 at 9:54
  • $\begingroup$ @RobTan "conformal transformations, that are a broad topic with many ramifications and that is analyzed in every text I saw about quantum field theory in curved spacetime. " That is an extremely narrow niche. Is it even physics? You ask for a proof, but apparently mean a mathematical proof. We prove things in physics by experiment and observation. Maybe you should ask your question in the mathematics forum. Or do you have an experiment in mind? $\endgroup$
    – John Doty
    Nov 8, 2022 at 15:27
  • $\begingroup$ @JohnDoty It is a general relativity calculation $\endgroup$
    – Rob Tan
    Nov 8, 2022 at 16:42
  • $\begingroup$ @RobTan Until you make contact with observable phenomena, a GR calculation is mathematics. Where is that contact? $\endgroup$
    – John Doty
    Nov 8, 2022 at 16:53
  • $\begingroup$ @JohnDoty I don't agree, you are basically saying that all theoretical physics is mathematics. Observable phenomena are formalized logically by physics, that means mathematically: is inevitable that a physical calculation is a mathematical calculation, but the subject is physical. What about every other general relativity calculation then? Or about Dirac formalism and so on. Anyway, I thank you also for the critics, but we are diverging from the subject of the question. Everyone seems to be concerned about the specific question I asked, but I didn't even want to link it to avoid this $\endgroup$
    – Rob Tan
    Nov 8, 2022 at 18:08
  • $\begingroup$ @RobTan GR was immediately connected to reality through the precession of Mercury's orbit. Einstein was (properly) excited by this. Eddington'e experiment followed. That's physics: theory and experiment guiding each other. $\endgroup$
    – John Doty
    Nov 8, 2022 at 18:21
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Consider how long it would it take you to write up your full derivation. Then consider how long it would take an answerer to check your derivation and then write an answer that confirms or disconfirms your derivation. If you are asking yourself to spend over an hour just to write your question, you are probably asking too much. If your question is essentially asking an answerer to spend over an hour to check your derivation and then to write an answer, you again are probably asking too much. Even half an hour is pushing the limit of what most answerers are willing to contribute per answer as pro bono (i.e., no charge) consultants.

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  • $\begingroup$ Eventually, before the question was closed, I would have asked to copy-paste the derivation someone may have done for personal interest, maybe highlighting the parts in which the problematic term appeared: it is a five minutes job and even less. Anyway, the question is closed now, so thank you for your interest in this $\endgroup$
    – Rob Tan
    Nov 13, 2022 at 16:04

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