One of the world's most renowned scientists, Stephen Hawking, has died at the age of 76. His was a theoretical physicist and studied at Cambridge University. He published a book called a Brief History of Time which sold over a million of copies. In 1963, Hawking contracted motor neurone disease and was given two years to live. At the time he was studying at Cambridge University. Neverless he went on to become a brilliant researcher. At first, he was able to speak but when he grew older he was no longer able to speak. To control what he said he had a special machine with words and he scrolled down them with his eyes. The sound was actually a computer but people knew him for that voice so he decided it would be his. Hawking's discoveries included the fact that black holes could emit heat. His daughter said if you asked him any question about physics he would always have an answer.