Are there problems posed with any frequency on MSE that are known to be unsolvable in a strong formal sense, such as being independent, undecidable, or blocked by Goedel's theorem? Requests for solution of NP-hard problems or graph isomorphism recur, but has there been any stream of questions like:
prove mathematics is consistent
solve the Continuum Hypothesis
test if two groups are isomorphic from their presentations
algorithm to solve arbitrary Diophantine equations
Clarification (edit). This is not intended as a question about policy, allowed questions, or what to close, but about the content of the traffic on MSE. I am requesting links or memories of examples, and briefly had added the [big-list] tag to the original posting, but dropped it when a list of questions in that tag looked like it is being used for different things. Adding the tag again.