One of the most contentious close reasons we have on the site is the one that designates real-world science questions as off-topic. The close reason is worded as follows:
"Questions seeking scientific solutions or explanations are off-topic unless they relate directly to a cited work of fiction."
Unfortunately, that last part seems to seriously muddy the waters: what does it mean for a science question to "directly relate" to a work of fiction? Just about every question asked on here cites some work of fiction. A question like "Could I make dilithium out of a lithium battery?" directly relates to Star Trek but I think it's exactly the kind of question we want to be off-topic.
On the other hand, most fictional works, even pure fantasy ones, operate with an implicit assumption that the laws of physics in the movie work just like the laws of physics in the real world, unless/until the work shows us differently. So many legitimate questions about the fictional universe will end up being answered using real-world science, because it's the same as the fictional science.
Different people, including different moderators, seem to fall at different points along the spectrum of possible interpretations, and it almost always leads to comment and chat "discussions" over which side a given question falls. So, can we try to pin down a community consensus over exactly where we draw the line?
For consideration, here are some previous meta questions that are related, but either don't quite answer this question, or else, there's no clear consensus in the answers:
- Are speculative science questions on-topic? (says that questions speculating about real-world science are off-topic)
- Are real world speculation questions still on topic? (a newer restatement/reiteration of the previous one)
- Are questions about current, or near-future science/technology on-topic? (says that questions about purely fictional science that has since become, or is likely to see become, real-science is on-topic; no clear consensus)
Also, here are some sample questions that are clearly asking about "real-world science" but with varying degrees of "related to a work of fiction". Note that I've tried to avoid questions from the very early days of the site, since their status may or may not reflect the current consensus (looking at you "Matrix Battery" question).
- "The Martian" and weight units [Closed]
- How could the matter converter in Tron Legacy generate an army [Open]
- How does mass conservation work in the MCU Ant-Man movie? [Open]
- How much power does the Martian heat ray output? [Closed]
- How can Quicksilver run with someone without injuring them? [Open]
I think it would also be a good idea to lay out a policy for what good answers to these questions -- assuming they stay open -- ought to look like. That will at least give us something to point users to when trying to help them keep within the scope of the site, or explain why their otherwise-factually-correct answers might be getting downvoted.