Stephen Hawking was: A scientist A genius An inspiration When Stephen Hawking was informed at the age of twenty-one that he had only a few years to live, it made him more determined than ever to find the answers to life's big questions. Diagnosed with amyotrophic lateral sclerosis at a young age, Stephen defied the odds and lived until the age of 76 - and his scientific discoveries changed the world. From building model airplanes as a child to his global travel experiences and the experience of a zero gravity flight, Stephen Hawking's life was extraordinary from start to finish.