For a decade now, the editors of Popular Science have been seeking out promising young researchers at labs across the nation, and for a decade we've been dazzled by the intelligence and creativity of the people we've discovered. This year's honorees, like the 90 others before them, represent the best of what science can achieve. Some are looking for specific solutions to daunting social problems, such as how to manufacture more-effective drugs or cheaply diagnose diseases in developing nations. Others are engaged in more-speculative work—studying solar plasma, inventing a new kind of geometry. All of them are brilliant, and all of them, perhaps most amazingly, are under 40. They have long careers ahead of them, which is yet another reason why we remain so optimistic about the future.