Science magazine is celebrating its 125th anniversary. In honor of that, they are taking a look at 125 big questions facing scientists within the next 25 years. We may live in an age where it seems like each day there are new answers to long standing questions. That doesn't mean, however, that we know about how Earth's interior works...or even whether or not an HIV vaccine is feasible. Essays on the first 25 questions (along with a host of other goodies) can be found here.