08/01/2012 12:35 GMT | Updated 08/01/2012 14:39 GMT

Stephen Hawking At 70: Physicist Forced To Miss Birthday Celebrations

Professor Stephen Hawking has been unable to attend his 70th birthday celebrations due to ill health. The world famous theoretical physicist and cosmologist was due to attend a free public symposium at Cambridge's Centre for Theoretical Cosmology, however was forced to watch the event online.

On Sunday, Cambridge University tweeted:

Entitled The State of the Universe, the event still went ahead, attended by luminaries including Astronomer Royal Lord Rees, Professor Saul Perlmutter and theoretical physicists, Professor Kip Thorne.

Addressing a packed auditorium, Lord Rees spoke of his admiration for Hawking, who was given two years to live when he was struck down with motor neurone disease in 1963.

"Even mere survival would have been a medical marvel, but of course he hasn't merely survived," said Rees. "He has become arguably the most famous scientist in the world - acclaimed for his brilliant researches, for his best-selling books, and, above all, for his astonishing triumph over adversity."

"The concept of an imprisoned mind roaming the cosmos plainly grabbed people's imagination... and what a triumph his life has been. His name will live in the annals of science; millions have had their cosmic horizons widened by his best-selling books; and even more, around the world, have been inspired by a unique example of achievement against all the odds - a manifestation of amazing will power and determination. His 'three score years and ten' deserve all the accolades they are getting this week."

Stephen Hawking