Soon after I enrolled as a graduate student at the University of Cambridge in 1964, I encountered a fellow student, two years ahead of me in his studies; he was unsteady on his feet and spoke with great difficulty. This was Stephen Hawking.
I learnt that he had a degenerative disease – amyotrophic lateral sclerosis – and might not live long enough even to finish his PhD. But, amazingly, he lived on for more than 50 years. Mere survival would have been a medical marvel, but of course he didn’t merely survive. He became the most famous scientist in the world – acclaimed for his brilliant researches; for his bestselling books about space, time and the cosmos; and above all, for his astonishing triumph over adversity.
Within a few years of the onset of his disease he was wheelchair-bound, and his speech became an indistinct croak that only those who knew him could interpret. But in other respects fortune favoured him. He married a college friend, Jane Wilde, who provided a supportive home life for him and their three children.
His scientific work went from strength to strength: he quickly came up with a succession of insights into the nature of black holes (then a very new idea) and how our universe began. In 1974 he was elected to the Royal Society, Britain’s main scientific academy, at the exceptionally early age of 32.
He was by then so frail that most of us suspected he could scale no further heights. But for Stephen, this was still just the beginning. He worked in the same building as I did. I would often push his wheelchair into his office, and he would ask me to open an abstruse book on quantum theory – the science of atoms, not a subject that had hitherto much interested him.
However, “Hawking radiation” became a hugely influential concept in mathematical physics; indeed, one of the main achievements of string theory has been to firm up and build on his idea. It is remarkable that it is still the focus of theoretical interest, a topic of debate and controversy even 40 years after discovery.
Stephen was not awarded the Nobel Prize because his idea was not confirmed by experiment. But in 2012 he was one of the first winners of the Milner Prize, worth $3m (£2.15m), and intended to recognise theoretical work.