Hawking will be known to most readers of this blog, an example of an individual whose extremely challenging disabilities have not prevented a life of incredible achievement. He has motor neurone disease, a condition that has progressed over the years and has now left him completely paralysed.
The diagnosis of motor neurone disease came when Hawking was 21, shortly before his first marriage. Forty-nine years later, he has been almost completely paralysed, but is still producing some of his finest work.
To speak, Hawking uses a computer fitted into his wheelchair. In latter years, he has operated it using a muscle in his cheek, selecting words, and those words are spoken by a synthesised voice. The voice, familiar to all of us, is no longer available as a speech synthesiser, but Hawking continues to use it because he considers it now to be his own.
Hawking was the Lucasian Professor of Mathematics at the University of Cambridge for 30 years. The post has previously been held by Isaac Newton and Charles Babbage, to name just two of the former eminent incumbents. Hawking retired from the post in 2009.
In 2007, to celebrate his 65th birthday, Hawking took a zero-gravity flight, during which he experienced weightlessness eight times. He became the first quadriplegic to float in zero-gravity. This was the first time in forty years that he moved freely, without his wheelchair. His plan is to take a sub-orbital space flight in 2013 on Virgin Galactic's space service.
Stephen Hawking is now Director of Research at the Centre for Theoretical Cosmology in the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge. He is best known for his contributions in the fields of cosmology and quantum gravity, especially in the context of black holes. Hawking's key scientific works have included theorems regarding gravitational singularities in the framework of general relativity, and the theoretical prediction that black holes should emit radiation, today known as Hawking radiation.
He has also written popular science books, in which he discusses cosmology in general, going a long way to making the subject accessible to the general public; A Brief History of Time was by far his best-selling title, staying on the Sunday Times best-sellers list for a record-breaking 237 weeks.
At the time of the diagnosis of motor neurone disease in 1963, Hawking's doctors gave his life expectancy as a further two or three years. Everybody who meets the man says he is a highly entertaining person, with a great sense of humour and an ability to inspire. Although he has continued to deteriorate slowly, gradually losing the use of his arms, legs, and voice, and now completely paralysed, Stephen Hawking has lived to celebrate his 70th birthday today. The world of science, indeed the world in general, is a better place because of it.