'A Brief History of Time'
Hawking's ever-expanding career was accompanied, however, by his ever-worsening physical state. By the mid-1970s, the Hawking family had taken in one of Hawking's graduate students to help manage his care and work. He could still feed himself and get out of bed, but virtually everything else required assistance. In addition, his speech had become increasingly slurred, so that only those who knew him well could understand him. In 1985 he lost his voice for good following a tracheotomy. The resulting situation required 24-hour nursing care for the acclaimed physicist.
It also put in peril Hawking's ability to do his work. The predicament caught the attention of a California computer programmer, who had developed a speaking program that could be directed by head or eye movement. The invention allowed Hawking to select words on a computer screen that were then passed through a speech synthesizer. At the time of its introduction, Hawking, who still had use of his fingers, selected his words with a handheld clicker. Today, with virtually all control of his body gone, Hawking directs the program through a cheek muscle attached to a sensor.
Through the program, and the help of assistants, Stephen Hawking has continued to write at a prolific rate. His work has included numerous scientific papers, of course, but also information for the non-scientific community.
In 1988 Hawking, a recipient of the Commander of the Order of the British Empire, catapulted to international prominence with the publication of A Brief History of Time. The short, informative book became an account of cosmology for the masses. The work was an instant success, spending more than four years atop the London Sunday Times' best-seller list. Since its publication, it has sold millions of copies worldwide and been translated into more than 40 languages. But it also wasn't as easy to understand as some had hoped. So in 2001, Hawking followed up his book with The Universe in a Nutshell, which offered a more illustrated guide to cosmology's big theories. Four years later, he authored the even more accessible A Briefer History of Time.
Together the books, along with Hawking's own research and papers, articulate the physicist's personal search for science's Holy Grail: a single unifying theory that can combine cosmology (the study of the big) with quantum mechanics (the study of the small) to explain how the universe began. It's this kind of ambitious thinking that has allowed Hawking, who claims he can think in 11 dimensions, to lay out some big possibilities for humankind. He's convinced that time travel is possible, and that humans may indeed colonize other planets in the future.