By Britta Guerke Jan 5, 2012, 2:06 GMT
London - When Stephen Hawking says something, the world listens - as evidenced by the reaction to his statement last year that belief in an afterlife is a 'fairy story' for people afraid of death.
British theoretical physicist Professor Stephen Hawking gives a lecture at Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, 20 June 2010. EPA/WARREN TODA
The theoretical physicist and cosmologist, who was diagnosed with a motor neurone disease aged 21 and communicates by means of a speech computer, has also addressed other fundamental issues such as why humanity exists and whether there is other life in the universe.
Against the expectation of medical experts, Hawking reaches the milestone age of 70 on Sunday.
'It's my view that all of us - not just theoretical physicists - want to know where we come from,' Hawking told German magazine Spiegel in 1988, following the publication of his best-selling book A Brief History of Time.
The science book, which sold more than 10 million copies, covered cosmological subjects such as the Big Bang theory, black holes, light cones and physical theories about the development of the universe.
Since the book's publication, Hawking has been considered a genius by much of the general public, as well as being a star in the scientific world.
He followed in the footsteps of Isaac Newton by becoming Lucasian professor of mathematics at the University of Cambridge, a post he took up in 1979 and held for 30 years before retiring.
One of his most significant successes came in 1974, when he discovered that black holes emit thermal radiation due to quantum effects, thereby unifying the three previously disparate areas of physics - quantum theory, general relativity and thermodynamics.
For years, he has been looking to build on the work of Albert Einstein by finding a formula that links together quantum theory and general relativity.
'I know it is media hype. They need an Einstein-like figure to appeal to. But for them to compare me to Einstein is ridiculous. They don't understand either Einstein's work, or mine,' Hawking said in an interview with the BBC.
What makes Hawking so fascinating in not just his interest in the great questions that occupy humankind and the desire to provide a sound scientific explanation for all phenomena.
It is also the symbolism of a man with an intellect that can seemingly reach the stars, but who is so disabled that he can do nothing for himself and has had to spend most of his life in a wheelchair.
'I'm the archetype of a disabled genius, or should I say a physically challenged genius, to be politically correct. At least, I'm obviously physically challenged. Whether I'm a genius is more open to doubt,' he said to the BBC.
The universe has preoccupied Hawking since his early youth. He had originally wanted to study mathematics. But University College, Oxford, had no mathematics fellow at the time, and Hawking applied to read natural sciences, specializing in physics.
After receiving a degree at Oxford in 1962, he stayed to study astronomy before enrolling at Cambridge to study theoretical astronomy and cosmology.
Shortly afterwards, he started developing symptoms of amyotrophic lateral sclerosis (ALS), a type of incurable motor neurone disease, and was given three years to live. That perspective, he has noted, made it clear to him that he could still achieve a lot.
Hawking's scientific career flourished, and he was elected as one of the youngest fellows of the Royal Society in 1974. He married language student Jane Wilde, and the couple went on to have three children before separating in 1991.
Little is known about Hawking's private life. In the late 1990s, Wilde published a book in which she described her scientist ex-husband as a tyrant at home who had be reminded on occasion that he was not God.
One thing is for sure: Hawking certainly does not live in fear of death.
'I have lived with the prospect of an early death for the last 49 years. I'm not afraid of death, but I'm in no hurry to die. I have so much I want to do first,' he said in an interview with The Guardian newspaper last year.
'I regard the brain as a computer which will stop working when its components fail. There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark.'
In answer to a question on how we should live, Hawking simply said: 'We should seek the greatest value of our action.'
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