"Why do we dream?" doesn't seem like it ranks in the top 10.
So I am not sure if you think the question is already solved or is it not actually a problem.
The contributions like "engineering problem at best" make me sure that we can't expect much.
Actual top10 problems:
http://en.wikipedia.org/wiki/Millennium_Prize_Problems
(they require knowing more than a little bit of science to even understand the question)