In a comment to my answer here I was asked:
and can you provide source for that this forum is only for mainstream physics, what is mainstream?
I thought that this was written in the help page, but cannot find it. It is sort of implied in the list of appropriate questions but there is no discouragement of crackpot theory type discussions in the red x list.
Is it my impression that somewhere the "mainstream physics" was emphasized? Anyway why isn't it?