My questions are getting closed a lot as "primarily opinion-based", which I understand might be entirely my fault.
One thing I don't quite understand is why this question got put on hold. I was really just asking about the state of current research with regard to a particular topic. My question got answered in the comments, but I think it's a shame that it got closed down.
In general: How should I ask questions about the state of current research without falling into the "primarily opinion-based" category? Of course people are going to disagree on the topic since the physical problem might or might not be solved, although I don't think that makes such a question subject to opinions in the sense of subjective accounts of the topic (which is what I thought the close option was for).