Stephen Hawking was born in Oxford, England, on January 8, 1942, 'exactly 300 years after the death of Galileo', as he noted.
By his own account, he didn't shine at St Albans School, where he was a secondary student. 'I was never more than about half way up the class,' he wrote. 'My classwork was very untidy and my handwriting was the despair of my teachers ... When I was 12 one of my friends bet another friend a bag of sweets that I would never come to anything.'
He went on to University College in Oxford, where he says he wanted to study mathematics but that it wasn't available, so he studied physics instead. He read for a PhD at Trinity Hall, Cambridge.
Today, he holds the post of Lucasian Professor of Mathematics at Cambridge, once held by Isaac Newton.
He was diagnosed with the wasting motor neurone disorder amyotrophic lateral sclerosis at 21, and told by doctors that he probably didn't have long to live.
Rather than sink into despair, Professor Hawking tells how, when he was in hospital, he saw a boy he knew die of leukaemia - 'it had not been a pretty sight' - and it reminded him that there were people worse off than him.