The "Oldest" answer Assume that a given question has several answers. So in the answer part there are 3 button "Active", "Oldest" and "Vote" When we clique on "oldest", we lead to a unique answer. Is this unique answer the first answer to the question? I doubt that the answer to this meta question is affirmative since it does not work for example on this question Finding a 1-form adapted to a smooth flow On the other hand the situation is different for the following question with several answers If $x_{n+1}= \frac{nx_{n}^2+1}{n+1}$ then $x_{n}=1$ So what does "oldest" signify?

oldest does sort by the answer time, however, the accepted answer will still be on top, even if it is not the oldest; the same applies to the other sort options.