You can't delete any of your questions or answers if you haven't registered. When my question has upvotes and unanswered for long time, it get deleted.
Valid unanswered questions will stay on the site forever, so they can be answered.Invalid questions, questions which break the rules or the law are deleted by Supervisors.
That is one of the "hot" unanswered questions in theoretical physics.
"Featured" questions are unanswered questions that Supervisors feel are interesting or important; it gives them more visibility, perhaps because they have remained unanswered for a long time.
Some post questions that are not important in their kind of what people are searching for. I suggest you send important questions(highly educated questions)so people could see it. If it doesn't work, ask your friends to answer your questions. I help people's unanswered questions because I don't want them to wait for a long time just for their question to be answered.
Not all - since there are new questions being added all the time. Additionally - some questions may stay unanswered for a long time - depending on the subject - and whether someone knowledgeable stumbles on it.
Archive Researchers tackle questions that have sat unanswered for long periods of time. Some of these are more difficult questions and require some research. They may recommend that the more interesting selections become Featured Questions.
This is unanswerable because people add and answer questions all the time, so the number is always changing.
Using this is a waste of time, you ask question's and you expect answer's but all you get is some crappy unanswered/relevant questions similar to yours.
Of coarse that's why the bad people don't go to jail every time!
No, The reason might be that there are alot of unanswered questions last time I checked over 8,000,000,000 Unanswered questions. And there is only over 2,000,000,000 Contributors not including the unregistered users. So it will take time but your answer will get answered sooner or later.
Unanswered questions concerning the Big Bang: 1) What drove the initial expansion of space? 2) Why did inflation stop? 3) What existed before the start of expansion? And does the word "before" have any meaning if there is no time?