World-renowned Cambridge scientist Professor Stephen Hawking has made a rare public appearance at a science festival in the United States.
Widely regarded as one of the most brilliant theoretical physicists of modern times, bestselling author, professor and scientist Stephen Hawking was on stage at the Seattle Science Festival. He was taking part a sell-out Luminaries event with other scientists and performers.
Professor Hawking, who was the Lucasian Professor of Mathematics at Cambridge University for 30 years, turned 70 in January. He was awarded America's highest civilian honour, the Presidential Medal of Freedom, by President Obama in 2009