Last week, I asked a question about an everyday physical phenomenon (In aluminum, how does electricity travel through the surface oxide layer?). I was fortunate enough to get two answers and some comments offering possible explanations. All of the proposed explanations seem at least somewhat reasonable to me, and both answers and a comment have attracted a positive score. Unfortunately, they don't agree with each other, and now I'm not sure which answer to accept.

  • One answer says that the aluminum oxide layer is porous and contains moisture, which causes it to conduct electricity.
  • Another answer says that the oxide layer is thin and fragile enough to be easily pushed aside when another metal conductor is connected.
  • A comment (which probably should have been an answer) attributes the observed conductivity to electrical breakdown of the oxide layer.

I tried offering a bounty (is that an appropriate thing to do?), but I haven't received any new answers and there is only one day left.

This isn't an opinion-based question; in principle, it would be possible to conduct an experiment to determine the correct answer (which might be a combination of several explanations that apply in different conditions). Also, I don't think my situation is covered by Which answer should we accept if multiple answers address the question? I can't tell which answer is most helpful because I don't know which one is correct. (If I knew, I wouldn't have asked the question!) Finally, I don't feel comfortable choosing based on the number of upvotes alone. Votes are a useful signal about the opinion of the community, but truth isn't determined by majority vote.

Naturally, feedback is welcome about the question itself. If you feel that it's unanswerable or that I wrote it in an unclear way, please say so! However, if possible, I think it would be best to avoid debating the physics of aluminum oxide here on Meta. That way, the discussion will be useful for future users who are in similar situations.

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    $\begingroup$ is that an appropriate thing to do? The bounty with the explanation "official sources needed" which you used is perfect for this issue, even though it didn't exactly work this time. $\endgroup$
    – user191954
    Commented Mar 9, 2019 at 8:50

1 Answer 1


It isn't compulsory to accept an answer. If you feel that neither answer is acceptable then do not accept either of them.

If you haven't received an answer that satisfies you then placing a bounty is the correct approach. It hasn't worked (so far) in this case, but that's the risk you run. It may simply be that none of the site members are experts in this field. If you placed the bounty after the two existing answers were posted (which appears to be the case) then unless you manually award the bounty it will simply disappear on expiration.

In your place I would require an answer to cite some experimental literature that I could read for myself. Without that you have no way of judging the accuracy of what has been posted. Given that neither of the existing answers provide this I wouldn't consider either of them an acceptable answer.


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