Welcome to PF!
You could browse the thread discussions and see if there any discussion that you can contribute to. As an example, someone posts about relearning classical physics as a senior citizen and you could recommend a good book like Susskind's Theoretical Minimum book on Classical Mechanics.
You could start a discussion on a topic that you'd like to know more about. Tell us what you know and where you get stuck. For example, you might be curious about why special relativity explains the magnetic field when current flows in a straight wire.
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When asking a question or solving a problem, we may view it as homework because if it looks like a duck, walks like a duck, and quacks like a duck, we conclude it's a homework problem.
We've had folks present a problem without showing us what they did. We would conclude its homework, and they would say they aren't students. However, we've also had students come here trying to trick us into solving their problems.
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Lastly, you could browse our site global guidelines. There are some topics we don't discuss. In particular, personal theories, fringe science like perpetual motion machines, impossible spacecraft engines, and several other topics,
We also don't review a person's work, such as an unpublished paper. We are not a peer-review site. We can and do discuss peer-reviewed papers published in respectable journals like Nature. Sometimes, we discuss arxiv papers if the science is mainstream but cutting edge from well-known authors and institutions.
We are a highly moderated site, so read our site's global guidelines to learn more.
Should you see any spam or questionable posts that violate our policies, use the report button to bring them to our attention. We appreciate these heads-up reports. It really helps our moderation efforts to keep the site clean.
Take care and enjoy PF,
Jedi