Hawking Says Colonize Space

Stephen Hawking wants humans to colonize space.   In recorded speech, he has pleaded for interplanetary travel, arguing that humans faced a grim future unless they spread out. 

His "A Brief History of Time," has sold millions of copies. A host of other books, including "A Briefer History of Time," have followed.

In his recorded message, Hawking said explaining the universe to the wider public was a duty, and that the issue had far more than just theoretical interest.

"If you understand how the universe operates," he said, "you control it in a way."