Stephen Hawking has died, according to a statement from his family. The British physicist, best known for his work on relativity and black holes, was 76.
"We are deeply saddened that our beloved father passed away today," the statement from his children Lucy, Robert, and Tim said. "He was a great scientist and an extraordinary man whose work and legacy will live on for many years.".
At 22, Hawking was diagnosed with a rare form of amyotrophic lateral sclerosis, and his doctors told him he had only a few years to live. Defying the odds, the Oxford-born Hawking became one of the world's leading theoretical physicists and a celebrity in his own right, despite his being confined to a wheelchair and relying on a voice synthesizer to speak.
Hawking's 1998 book, A Brief History of Time: From the Big Bang to Black Holes, has sold more than 20 million copies and has been translated into dozens of languages.
Here's how a few notable people reacted to the news of Hawking's death on Twitter: