Updated 8 Aug 2022

Here are 20 most viewed questions that need answers. Some of these questions may have answers with negative votes. Only questions with upvotes will be removed from this list. This list will be updated as questions are answered (which will be replaced with other questions that need attention.)

How you can help:

  1. Answer some of these questions!
  2. Edit questions to make them more polished.
  3. Start a bounty on some of the more interesting questions.
  4. Support askers and answerers with upvotes where deserved. If you take a look at the edits made to this question, you can find questions that have been answered by the lovely members of the community.
  5. If the question is not appropriate for this site, downvote it or vote to close it.

I modified a query to fit Physics.SE to give unanswered questions (that are open) and have a high number of views. You can also run the query for one or two answers if you want.

I did find that there were some questions that were quite popular and disappointingly did not contain any answers.

If anyone would like to handle some of these questions, that would be amazing!

Please edit these questions as you see fit (and fix any weird tags.) There is a lot of re-titling to be done and much-needed language cleanup or clarity in the body of the questions.

Here is the query.

Hit the 'ole star button on this meta post to get notified of updates.

Here are the top 20 questions needing answers:

  1. How long would it take for a cup of water to fully evaporate?
  2. Quantum fields from cluster-decomposition principle
  3. ratio between conduction current and displacement current
  4. What substance is being sprayed during this scene in Chernobyl?
  5. Angular momentum of a 2-dimensional system in polar coordinates
  6. How to calculate the magnetic dipole moment of a bar magnet?
  7. What is Curvature of eye lens?
  8. Experimental test of the non-statisticality theorem?
  9. What is the difference between Non-harmonic oscillation, Anharmonic oscillation and Complex harmonic oscillation?
  10. The reciprocal lattice of HCP lattice
  11. PDF lecture notes of various courses by Leonard Susskind
  12. Why is the Fermi level (energy) shfited in doped semiconductors?
  13. How can one calculate diffusion velocity given the diffusion coefficient?
  14. When do I know if energy stored in an object is 0 or nonzero? (Heat transfer)
  15. Three particles case, finding ground energy state
  16. Why do my glasses make the ground look tilted?
  17. Most rigid materials
  18. Finding the probability that a $1s$ electron in ${}^3$H remains in the $1s$ state after beta decay to ${}^3$He with the sudden approximation
  19. Trouble justifying calculation of force on a sphere due to radiation pressure
  20. Forces on two boxes

I will update the above list periodically.

  • 2
    $\begingroup$ So not all of these would be as impactful if they were answered as the view counts suggest. But at least half are solid, good questions that deserve answers; kudos for searching these up! $\endgroup$
    – knzhou
    Commented Feb 26, 2019 at 13:30
  • $\begingroup$ @knzhou Perhaps these questions could be flagged if they are too homework-y. Or if someone wants to answer them in more of a "hand-holding" way versus just feeding an answer to someone looking to cheat? $\endgroup$ Commented Feb 27, 2019 at 2:58
  • 3
    $\begingroup$ I'd suggest improving your query by requiring score $\ge 1$. It seems like most or all of the zero score questions are off-topic questions that no one bothered to downvote or close. $\endgroup$
    – Chris Mod
    Commented Feb 27, 2019 at 15:14
  • 2
    $\begingroup$ @Chris That's not the point. If it has high views and an unresolved status, it's getting a bunch of visitors and not giving them anything. If they're bad questions then they should be fixed / closed / deleted as appropriate, but they still being on the query. $\endgroup$ Commented Feb 27, 2019 at 15:29
  • 2
    $\begingroup$ @EmilioPisanty Fair enough. Maybe we should edit in "5. If the question is not appropriate for the site, downvote it or vote to close it." under "How you can help?" $\endgroup$
    – Chris Mod
    Commented Feb 27, 2019 at 15:32
  • $\begingroup$ @Chris I'd say go for it. $\endgroup$ Commented Feb 27, 2019 at 15:53
  • 1
    $\begingroup$ @MelanieShebel Actually I don't understand the premise of this thread at all. If there are unanswered questions, some of them will have more views than others. That truism has no relevance to whether the questions should be left open on Physics SE at all, or whether they are worth answering, IMO - unless you are saying that the mere act of viewing a question somehow makes it worthy of being answered, even though you don't know what it asks until after you finish viewing it? (Maybe there's a new interpretation of quantum mechanics lurking behind that hypothesis....) $\endgroup$
    – alephzero
    Commented Feb 27, 2019 at 18:01
  • $\begingroup$ Is there a way to see how often users with a certain amount of rep (say 200+) views a question? That would partially eliminate the "people only viewing site through Google" affect. $\endgroup$ Commented Mar 11, 2019 at 3:59
  • $\begingroup$ @PyRulez I think the 'people viewing through google" effect is something very important, since a huge proportion of SE traffic is from google/search engines (meta.physics.stackexchange.com/q/9533). We should look at the questions which people are getting directed here for; it's not something which should be eliminated. I'm sure that if we only consider views from people with >200 rep, there'd be a very small amount of data. But I don't think SEDE tracks that. $\endgroup$
    – user191954
    Commented Mar 11, 2019 at 12:17
  • $\begingroup$ @Chair fair enough. I guess it's a debate of whether having a lot of views means that we should focus on them. In my opinion, a question with a lot of views that is dumb is less important than a well thought out but less popular question. People are free to focus on the ones they prefer, however. $\endgroup$ Commented Mar 11, 2019 at 13:43
  • $\begingroup$ @PyRulez "debate of whether having a lot of views means that we should focus on them" exactly: as the revision history of this post shows, a lot of those questions with many views are worth closing (i.e. are bad fits for the site, if not objectively). But I do think it was helpful for us to be conscious of the fact that people are coming to PSE for that content and walking away unhappily. $\endgroup$
    – user191954
    Commented Mar 11, 2019 at 13:49
  • $\begingroup$ @Chair the issue is that some are on topic, but not very good questions. However, it's not clear how to handle these other than by answering them. $\endgroup$ Commented Mar 11, 2019 at 13:53
  • $\begingroup$ @PyRulez Hmmm, I think that most of the remaining questions are quite good, but yeah, if you think that they aren't very good questions, you can't do anything but downvote them and if the score drops enough, the Roomba script may pull them out. $\endgroup$
    – user191954
    Commented Mar 11, 2019 at 14:01
  • $\begingroup$ @Chair well, the issue is that if this is supposed to be a long term thread, I could forsee a future where all the good questions get answered on the list, and bad (but still technically on topic) ones accumulate. I guess the best to fix that will be more obvious when/if we get there. $\endgroup$ Commented Mar 11, 2019 at 14:03
  • $\begingroup$ @PyRulez Indeed, even I was a bit curious: if we keep updating this list, will we end up with a list of useless question which nobody wants to answer, or a list of extremely hard questions, or a list of questions which don't have a particularly high number of views? Our best bet is to wait and see. $\endgroup$
    – user191954
    Commented Mar 11, 2019 at 14:06

1 Answer 1


Frankly, I think the questions no. 6 and 7 in v1 of your list should be closed and deleted. I don't think they're particularly on-topic (I don't think they really fall into what we intended either the resource-recommendation or the specific-reference tags to cover), the books they're asking for are unlikely to exist, and they're not doing anybody any good by staying up. They've each been seen some 6-7k times, so that's some 13,000 times that people have been disappointed by what they find here. Closing them is unlikely to help with the disappointed-visitor syndrome - there's really no point to keeping them around.

More generally, if any borderline-on-(off-)topic unanswered questions end up in that list again, I think it's worth thinking very carefully about whether they should remain open and undeleted: if they're not good fits for the site, and they're unlikely to get answered, then what good does it do to have those questions accumulating thousands of views and conveying a negative impression of the site?

  • 1
    $\begingroup$ What consensus do you refer to in your close comment? Afaik, such questions are on topic (looking for specific & hard to find document, which is what specific ref. is some for, no?) $\endgroup$
    – Kyle Kanos
    Commented Feb 27, 2019 at 14:59
  • $\begingroup$ @KyleKanos The tag description for specific-reference starts with "Use this tag for questions seeking a single specific paper or a short, non-open-ended list of references" (emphasis mine). That doesn't really describe a solutions manual. There doesn't seem to be a consensus, so I've started a meta post, Requests for Solutions Manuals, to discuss it. $\endgroup$
    – Chris Mod
    Commented Feb 27, 2019 at 15:26
  • $\begingroup$ @Chris so the short, non-open-ended list of references that follows your selectively emphasized portion means what, exactly? And how does a solutions manual, which, if it exists, would satisfy the short & non-open-ended list? $\endgroup$
    – Kyle Kanos
    Commented Feb 27, 2019 at 15:29
  • $\begingroup$ @Kyle Is this an academic debate regarding the precise text that (others also used to) close the question? Or do you seriously feel that either of those two questions improves the site and should be left open? (Not to imply that you'd have to be kidding to say so, but I don't have time for the pointless debate.) $\endgroup$ Commented Feb 27, 2019 at 15:33
  • $\begingroup$ @KyleKanos I'm not 100% what is meant by short, non-open-ended list of references, but I'd assume it would refer to a short list of papers. Either way, I think the language in the specific-reference tag description should be clarified once we decide if these questions are on-topic or not. $\endgroup$
    – Chris Mod
    Commented Feb 27, 2019 at 15:35
  • $\begingroup$ Part of the problem with these questions is that they are made without knowing if the solution manual even exists. At least if you ask for Dr. so-and-so's thesis paper, you can be sure that it actually exists. $\endgroup$
    – Chris Mod
    Commented Feb 27, 2019 at 15:38
  • $\begingroup$ @emilio what I'm saying is that your close comment on both posts say that there is a consensus that such questions are off-topic. I am not aware of such a consensus and would like to know where you're pulling that from. DavidZ's comment on the one seems to even indicate the contrary... $\endgroup$
    – Kyle Kanos
    Commented Feb 27, 2019 at 15:41
  • $\begingroup$ @Kyle As I said, I'm not interested in that pointless debate - I'm travelling and I don't have time for it. If you have specific points to raise about actual site policy, by all means do so - probably in Chris's new question. $\endgroup$ Commented Feb 27, 2019 at 15:51

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