I tried to change the title of this question: QM without complex numbers, to "Quantum mechanics without complex numbers" which I think is more descriptive (I mean the definition of QM might be obvious to most people here, but titles in publications and StackExchange questions look better or at least more professional if things like this are spelled out).

Unfortunately this question (closed immediately as a duplicate) from fewer than 3 months ago caused it to be impossible for me to make that edit: Quantum Mechanics without Complex Numbers.

Shall we make the original question (with 100+ upvotes) have the more descriptive title and change the closed version's title?

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    $\begingroup$ Cold answer: Let it go. $\endgroup$ Commented Mar 13, 2021 at 21:28
  • $\begingroup$ @AccidentalFourierTransform actually if the question was renamed earlier, the recent duplicate would never have been asked! $\endgroup$ Commented Mar 13, 2021 at 22:06
  • $\begingroup$ Given the number of duplicates asked, one more or less doesn't matter too much ... and you can only ever avoid one duplicate (which is now avoided). $\endgroup$ Commented Mar 14, 2021 at 11:54
  • $\begingroup$ @user1271772 ...or it would have been asked with a different title? $\endgroup$ Commented Mar 14, 2021 at 17:51

2 Answers 2


The recent duplicate question looks like a candidate for the roomba, so it may not present an obstacle for much longer.

  • $\begingroup$ Excellent. I was considering that it might be a worthwhile idea to delete the question but that seemed a bit severe. It wouldn't have qualified for the roomba deletion, since it had a positive net score when I first asked this question on Meta, but with the recent downvote it will eventually qualify. $\endgroup$ Commented Mar 13, 2021 at 22:03
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    $\begingroup$ It would be a shame to have it go, given that it has more substance than the other question. Not to mention that than again, only one of the two titles appears. $\endgroup$ Commented Mar 14, 2021 at 11:43

Leave it as it is.

(Or swap it. But I don't see a benefit in that, so I'd say it is better to leave it.)

First, having duplicates serves exactly the purpose of directing people searching for the same problem in different formulations (which includes different titles) to the same set of answers. This purpose is served here.

Second, the purpose of duplicates is primarily to redirect people searching for sth. to the right answer. It is not clear to me whether people are more likely to use "quantum mechanics" rather than "QM". (Just look around: People are lazy to spell out things and use abbreviations all around. I agree that using less abbreviations would be better (in particular those which are not easily understood to non-native speaker like "SHM", I still stuble across that one, and it took me long to figure it out!). But it might well be that people are more likely to use "QM" - would be interesting to find out, maybe SEDE can be used for that.)

Finally, I think the new duplicate question is more valuable than the original question: With this, I don't mean the quality of the question as such (the two questions are aligned rather differently), but what one learns from reading the question. From reading the first question, I don't learn much, except that this might be an interesting question. From the new question, I learn how to express complex numbers as 2x2 matrices, which is valuable, and as far as I can see not explained in any detail in any of the answers. Thus, I think it would in fact be beneficial if some people end up at the duplicate question first.

Finally, looking at the side bar it seems that this question has lots of duplicates, some using QM and some quantum mechanics. So the very fact that the title has QM or quantum mechanics will likely not be enough to redirect people to any of those questions - there's enough different ways to phrase the very same question in the title.

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    $\begingroup$ FWIW, common search engines are smart enough to automatically expand "QM" to "Quantum Mechanics", if you give them enough context, eg QM complex numbers brings up relevant results in DuckDuckGo & Google. $\endgroup$
    – PM 2Ring
    Commented Mar 14, 2021 at 14:12

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