Tour says we can ask about "History and development of mathematics" - is it valid anymore since History of Science and Mathematics SE is already alive? Won't we be stealing the life out of it still allowing questions of that sort here?
I'm HDE 226868, one of the mods on HSM, finally writing up something for this. I should add that I put forth a similar question on Physics. There's absolutely no need to follow the same viewpoints or logic, but the answers do show some interesting ideas.
Anyway, here are some important points from the community on HSM:
- We love good questions. Everybody does, I know, but the particular types of historical questions we're after don't, in general, have textbook answers. My textbook on American history will go on at great length about the World Wars, Reconstruction, the counterculture movement, and all the other things that shaped the country's past and led to the present . . . but too often the mathematics and science attract little attention. Sure, World War II was perhaps more important than the discover of the $\pi$ mesons, but they're still important. You won't find answers to HSM questions easily - and it's hard to find material to ask about in the first place! - so we love it when we get good, well-thought-out questions.
- We don't want to take questions away from any other sites. Yes, we're in beta, and Mathematics has graduated, so it could be argued that we need the questions more, but let's face it: If a question is on-topic on multiple sites, it could be asked on any of those. We all want good answers to our questions from true experts. Ask in a place where the experts are. If they happen to reside on site A, then go there. If they reside on site B, go there. If they're on both, then do some thinking and then make your pick. But we'd love to have experts on the history of science and mathematics active on HSM - not just Physics, Mathematics, Earth Science, etc. We're not going to demand questions from you. It's your choice, not ours. As quid said,
However, I would advise against being too active in getting questions migrated here [to HSM]. This might alienate others (sometimes also for unreasonable reasons but still). As long as a question is well-received on another site, I think there is nothing that should be done. (Normally, migration is a sub-point of off-topic; if the latter does not apply there is no case for migration.)
The idea is up for debate on HSM (e.g. this meta post and an earlier one). We have not yet reached a true consensus. I'll try to keep you informed as to how that works out. It seems like we as a community would love to have some newer questions migrated, but we don't want a huge flux. Again, see quid's answer.
We've had many migrations from Physics, and a decent amount from Mathematics - thank you, Arthur Fischer, for communicating with us on the specific ones - and we'll continue taking them, so long as either the asker supports the migration or Mathematics.SE decides that the question is off-topic. Don't feel obliged to migrate.
I'm far from an active user on Mathematics, so I clearly shouldn't try to speak for the community here. I know, that's tough, because that's the whole point of the question. Still, I'll try.
If you collectively decide to keep math-history questions on-topic, we won't hold it against you - and you won't be hurting us. We've been doing okay. Would it be awesome to have more activity? Yes. Absolutely. But it won't kill us to miss out on some. Mathematics gets about one-to-three per day (looking at the past few weeks). That could help us, sure, but it's not a make-or-break amount (no offense meant). So I hope this clears that up.
As for whether or not math-history questions should be on-topic here. . . I'll leave that for the community to decide. I see no problem with choosing one option or the other, really.
Apologies, by the way, for taking so long to get around to this. We've all been a bit busy lately.
I'm not active on either site, but I have general thoughts on this.
Stack Exchange is experiencing a drift to fragmentation right now; a slew of narrow-scoped sites have been proposed on Area 51, many of which are covered scope-wise by already existing sites to varying extent.
Even though it is in beta, large parts of the scope of hsm.SE are covered by other sites, namely the respective science sites (physics.SE, chemistry.SE, biology.SE, philosophy.SE, math.SE, ...). This only makes sense if the larger sites said, "let's get rid of this fragment of our scope", and fans created their own site. If that's not the case there is no reason at all for existing sites to change scope or policy.
If hsm.SE fails because they don't have a scope that can stand on its own given existing sites, that is as it should be. Finding that out is one of the main purposes of beta, after all!