The Stack Overflow faq says:
We feel the best Stack Overflow questions have a bit of source code
I think the Physics Stack Exchange faq should say:
We feel the best Physics Stack Exchange answers include external citations.
I have seen more than one completely incorrect answer accepted on Physics Stack Exchange, which I have not seen on Stack Overflow. I suspect this is because unlike coding, it's hard to immediately verify physics claims. For this reason, I think external citations to trusted sources are especially important for physics answers.
I would also like to see more answers clearly indicate their logical foundation. Is your answer...
- Original research?
- Predicted by peer-reviewed theory, but unverified?
- Indirectly experimentally verified?
- Directly experimentally verified?
Don't make us guess!
I have seen many answers here based on rock-solid, universally trusted theory. This is great! However, if experimental verification has not actually been cited, this should be clear. Experiment frequently lags behind theory, but has been known to expose flaws and loopholes in theory, and very occasionally, invalidates theory entirely.
An example from my personal experience: Can I levitate an object without using an electromagnet?
For months, the accepted answer was basically "No, because of Earnshaw's theorem". This was an excellent answer; Earnshaw's theorem is rock-solid, universally accepted theory. End of story? No, because this answer was also good enough to include an external citation. As the external citation made clear, there are loopholes in Earnshaw's theorem that make the correct answer 'yes', not 'no'. The correct answer is supported by a picture of a levitating object - direct experimental verification.