From inventing Dyson Spheres, a sci-fi conceit postulating habitable shells around Sol-like stars, to "space chickens" and trees that grow in comets, Freeman Dyson was not afraid to go out on a cosmic limb. It would be wrong, however, to categorize him as a publicity-hungry peddler of headline-grabbing ideas. In his 60-year career as one of planet Earth's most distinguished scientists, several things characterize Dyson more than anything else: compassion, caution and overwhelming humanism.

In addition to his work as a scientist, Dyson was a renowned and best-selling author. His book A Many-Colored Glass tackles nothing less than biotechnology, religion and the role of life in the universe. He didn't not shy away from controversy; his critiques of the politics of the global warming debate raised the hackles of some environmentalists. But far from wielding his conclusions like a bludgeon, Dyson wanted younger generations of scientists to take away one thing from his work -- the necessity to create heresies of their own.