My question was closed1 on Phys.SE. Can you recommend me another Internet site where my question might be on-topic?
Here we keep a list of other Internet sites that might help students2 of physics. One site per answer. To keep the list at a reasonable size, please only include sites which fulfill the following criteria:
The site should be a physics site or have a physics section.
The site's scope should be wider than Phys.SE's scope. In particular, it should welcome questions in all areas of physics and at any level.
The site should be free of charge.
Please avoid blatant promotion. This meta post is meant as a service for students in need.
2 The word student includes self-student.