The wheelchair-bound Hawking, who only recently retired from a post once held by Isaac Newton, had previously talked to the magazine in the run-up to celebrations for his 70th birthday.
Unfortunately, he wasn't able to come to the celebration on Sunday because he was too ill to attend. He was known as the world's most widely recognized living scientist, and was hailed by colleagues as one of the most brilliant theoretical physicists since Einstein.
Hawking, the author of the international bestseller "A Brief History of Time" in 1988, was honored for his breakthroughs into theories of time and relativity, but also for his ability to make complex science accessible.
At a birthday symposium for the scientist, who was diagnosed with motor neuron disease in 1963 and told he had barely two years to live, Britain's astronomer royal said Hawking had defied medical and scientific odds. The head of his elite Cambridge University said he had "changed our perception of the universe."
"It's wonderful that we are celebrating Stephen's 70th birthday. It's a chance to thank him for the many insights he's given us about the universe, and ... for the inspiration he's offered to millions by achieving so much against all the odds," Astronomer Royal Martin Rees told an audience of scientists, students and reporters.
Hawking had been due to speak on Sunday at Cambridge, where as an undergraduate he first became fascinated with cosmology and the state of the universe, but colleagues said he was too poorly to attend. Hawking had recently been in hospital and was discharged on January 6, Cambridge's Vice-Chancellor Leszek Borysiewicz said.
"Unfortunately ... his recovery has not been fast enough for him to be with us today," Borysiewicz said. Hawking chose to call his speech at the State of the Universe symposium "A Brief History of Mine." A spokeswoman for the university said the speech would still be delivered and Hawking would be watching the symposium from his home in Cambridge, where he is recovering.
Almost completely paralyzed by a form of motor neuron disease called amyotrophic lateral sclerosis, which attacks the nerves that control muscles and gradually stops them from functioning, Hawking is wheelchair-bound and uses a computerized voice synthesizer to speak.
When as a bright and enthusiastic 21-year-old PhD student he was diagnosed with the disease, doctors told him he would probably not make it much beyond the age of 23.
Yet in the almost half a century since, Hawking has broken new frontiers with research into theories of time, space, relativity and black holes. Rees and others have hailed him as a modern-day Einstein and said his work has shed light on the origin of the cosmos, the nature of time, and the ultimate fate of the universe.
Currently the director of research at the Department of Applied Mathematics and Theoretical Physics at Cambridge, Hawking also founded the university's Center for Theoretical Cosmology and only recently retired from a post known as the Lucasian Professorship of Mathematics, a title once held by Isaac Newton.
Bringing Science to the Masses
Despite having a mind that appears to work on a far higher level than most other human beings', Hawking has always made an effort to bring science to the masses.
He has featured on the hit U.S. cartoon show The Simpsons several times, and in Star Trek as a hologram of himself. His voice, famous across the world, also featured in Pink Floyd's 1994 album Division Bell.
"His ability to engage people in the process of scientific discovery through his books, lectures, and television programs has opened countless inquisitive minds to a universe full of possibilities," said Justin Rattner, chief technology officer at Intel, which provides Hawking's voice synthesizer.
Hawking's health has deteriorated over the years and he now uses twitches in the muscles in his cheek to choose letters or words on his voice computer to allow him to communicate. This means his speech has slowed dramatically, to a current rate of around one word per minute.
Kip Thorne, an acclaimed American theoretical physicist and long-standing Hawking collaborator who was also due to speak at the symposium, said Hawking's illness had both hampered him and pushed him to new limits.
"When Stephen lost the use of his hands and could no longer manipulate equations on paper, he compensated by training himself to manipulate complex shapes and topologies in his mind at great speed," Thorne said.
"That ability has enabled him to see the solutions to deep physics problems that nobody else could solve, and that he probably would not have been able to solve, himself, without his newfound skill."