He was there in spirit, but sadly not in person. Stephen Hawking missed his own 70th birthday party yesterday at Cambridge University on doctor's advice – he was recovering at home from an infection that had put him in hospital for a few days last week.
The world's most famous living scientist, who was diagnosed with motor neurone disease in 1963 at the age of 21 and given just two years to live, nevertheless used a pre-recorded speech to deliver his birthday lecture.
The packed auditorium included the Astronomer Royal, Sir Martin Rees, Professor Saul Perlmutter, the Nobel Prize winner in physics last year, the businessman Sir Richard Branson and the model and former Cambridge arts student Lily Cole.
In a highly personal talk, Hawking spoke movingly of the role his father played in picking him up from the devastating diagnosis when he was just beginning his PhD at Cambridge University – and how his doctor dropped him as a hopeless case and then never saw him again.
"My mother realised something was wrong and took me to the doctor," Hawking said. "I spent weeks in Bart's Hospital [in London] and had many tests. They never actually told me what was wrong, but I guessed enough to know it was pretty bad, so I didn't want to ask.
"In fact, the doctor who diagnosed me washed his hands of me, and I never saw him again. He felt that there was nothing that could be done. In effect, my father became my doctor and it was to him that I turned for advice."
His father, a researcher in tropical diseases at the Medical Research Council in Mill Hill, initially opposed Hawking's early interest in mathematics and wanted his son to pursue instead a career in medicine.
The title of Hawking's talk, "A Brief History of Mine", was a deliberate play on the title of his first popular science book, A Brief History of Time, which has sold more than 10 million copies worldwide since it was published in 1988.
His friend and fellow cosmologist Kip Thorne joked yesterday during his own talk on the golden age of black holes that he measures the sales of his own popular science books in "milli-Hawkings".
Hawking said he decided to write a popular science book to pay for his rising care costs and the fees of his children's schools, although the main reason was because he enjoyed it, he said.
"I never expected A Brief History of Time to do as well as it did. Not everyone may have finished it or understood everything they read. But they at least got the idea that we live in a universe governed by rational laws that we can discover and understand," he said.
His talk yesterday began with his birth on 8 January 1942 in Oxford, took in his early childhood in London, when he had a passionate interest in model trains (he even dreamt of electric trains), and ended with his current interests in the existence of many different universes, encapsulated in a revolutionary idea known as M-theory.
"M-theory predicts that a great many universes were created out of nothing. These multiple universes can arise naturally from physical law," he said.
"Each universe has many possible histories and many possible states at later times, that is, at times like the present, long after creation.
"Most of these states will be quite unlike the universe we observe and quite unsuitable for the existence of any form of life.
"Only a very few would allow creatures like us to exist. Thus our presence selects out from this vast array only those universes that are compatible with our existence.
"Although we are puny and insignificant on the scale of the cosmos, this makes us in a sense lords of creation," Hawking concluded.
Hawking symposium: the Party guests
The model and actress Lily Cole, last year awarded a double first from Cambridge
Lord Martin Rees, president of the Royal Society and astronomer to the Queen
Professor Saul Perlmutter, the American astrophysicist who won the Nobel Prize in physics last year for the co-discovery of dark energy
Justin Rattner, Intel vice-president, who directs its research into microprocessors and communications
Sir Richard Branson, the billionaire entrepreneur and CEO of the Virgin Group