At twenty-one, in his first year of doctoral research at Cambridge, Stephen Hawking was diagnosed with a motor neuron disease and told he likely had about two years left to live. For a young physicist who had barely begun his career, it felt like being handed a closing door.
He fell into a depression for a time, but slowly returned to his work, reasoning that if he was going to die soon anyway, he might as well spend the time on physics worth doing. The disease progressed far more slowly than predicted, gradually taking his ability to walk, then to write, then eventually to speak unaided.
By the mid-1980s he had lost his voice entirely after an emergency tracheotomy, and began communicating through a computer-synthesized voice operated first by hand, and later, as his condition worsened further, by twitching a single cheek muscle to select letters and words one at a time.
Working almost entirely through that slow, effortful process, he produced landmark work on black holes and the origins of the universe, and wrote 'A Brief History of Time,' which sold over ten million copies and made cosmology approachable to millions of readers who had never studied physics.