As far as I know on this physics stack are far more questions posted than other stacks. But why is that. I can't imagine that a study of biology, chemistry or history etc. would comprise less detailed information or question. Is that because in physics is so much unclear comparing to other studies or is it very difficult to understand is well, or are there just more students doing physics or is it just more interesting?
Looking at the sciences only,1 the total numbers can be found here (sorted by total number of questions). I've made an abridged table here:
Site Quest. -------------------- Math 573,000 Stats 74,000 Physics 72,000 MathOverflow 69,000 Chemistry 14,000 Biology 11,000
All of these sites are more than 3 years old (with MO, Math, Stats & Physics all being more than 5), so I don't think time is a factor here.see below What probably is a factor is the number of users:
Site Users -------------------- Math 241,000 Stats 78,000 Physics 81,000 MathOverflow 53,000 Chemistry 16,000 Biology 14,000
There are 5 times as many users on Physics as Chemistry & Biology, which seems to correlate to the 5 times as many questions found here than there.
Why there are 5 times as many users here, I'm not sure. But, I suspect it boils down to several factors: site policy, popularity (both academic & general interest), and difficulty of subject among them.
Response to criticism:
It was presented in the comments that age should be a factor in the number of questions. On a naive level, it makes sense: if you've been around longer, you're likely to accrue more questions. And this is sorta backed by data:2
All data taken from the SE team, but I'm putting a cap at 1e5 (which ignores a few sites, including Math.SE & SO).
But look at ~40500 (which corresponds to about 5 years, 8 months ago). That's quite the spread of question totals on a single date! Look at the table below, these are the sites that are 5 years, 8 months old.
Site Q U -------------------------- Web Apps 19k 69k Arqade 65k 82k Webmasters 23k 45k Cookign 14k 29k GameDev 31k 61k Photography 16k 31k Stats 76k 79k Math 576k 242k DIY 22k 31k GIS 65k 49k TeX 108k 79k AskUbuntu 219k 328k
Which is just fairly inconsistent with the naive hypothesis that age should be important. Going back to the graph, there are some younger sites that have more questions than older sites, including Russian SO (81k questions in 1 year)!
So while it's reasonably true on a very naive level, I don't see how someone can claim it as an important factor, as was done in the comments.
1. The technology sites dominate, with Stack Overflow having over 11 million questions at the time of writing; Ask Ubuntu & SuperUser have more than 200,000 questions as well. All three of those sites have more than 300,000 users as well.
2. A log-linear version of the plot can be found here; this shows the roughly linear fit (meaning power-law relation, roughly n=-71 at R-sq=0.47).