American astrophysicist and Twitter celebrity Neil deGrasse Tyson tweeted a photo of himself and Hawking, saying that his passing has "left an intellectual vacuum in his wake". But it's not empty.
The best-known theoretical physicist of his time, Hawking wrote so lucidly of the mysteries of space, time and black holes that his book, "A Brief History of Time", became an global best seller, making him one of science's biggest celebrities since Albert Einstein. "Stephen excelled at both". "It is a complete understanding of the universe, why it is as it is and why it exists at all", Hawking added. "Stephen was a joyful and lighthearted person, not to be burdened by excessively respectful and convoluted interactions", he says.
Hawking was born on January 8, 1942, in Oxford, England. He was diagnosed with ALS when he was 21, while a doctoral student in cosmology at the University of Cambridge. The couple split after 25 years and he married his former nurse, Elaine Mason, but the union broke down amid allegations, denied by him, of abuse. "I fell over and had great difficulty getting up", he told the audience.
According to John Boslough, author of "Stephen Hawking's Universe", Hawking became deeply depressed.
"A star just went out in the cosmos", tweeted Lawrence Krauss, a theoretical physicist and cosmologist. Still, Hawking progressively lost use of most of his muscles, and for the last three decades of his life was communicating nearly exclusively through a voice synthesizer.
He followed up "A Brief History of Time" in 2001 with the more accessible sequel "The Universe in a Nutshell", updating readers on concepts like super gravity, naked singularities and the possibility of an 11-dimensional universe. The book sold more than 10 million copies, and has been translated into 35 languages. He relished making cameo apparitions on television shows such as Star Trek: The Next Generation, The Simpsons and The Big Bang Theory.More news: Man Utd boss Mourinho blasts de Boer over Rashford remarks
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Hawking, who had travelled to China previously, even visiting the Great Wall in 2002, posted on Weibo about black holes and other phenomena, and wrote in one message that being on China's leading social media platform was "a source of great inspiration". In the early 1970s, he began to investigate what quantum physics could reveal about the event horizon, a black hole's surface of no return.
Hawking's formidable mind probed the very limits of human understanding both in the vastness of space and in the freakish sub-molecular world of quantum theory, which he said could predict what happens at the beginning and end of time.
In 2004, he announced that he had revised his previous view that objects sucked into black holes simply disappeared, perhaps to enter an alternate universe.
This emission, he reasoned, should ultimately lead the black hole to shrink and disappear.
Hawking's doctors gave him almost two years to live but he defied the medical history and survived for decades.