Professor Stephen Hawking, one of the world's finest scientific minds, has died at the age of 76, a family spokesman said.
He died peacefully at his home in Cambridge in the early hours of Wednesday morning.
At the age of 22, Hawking was told he only had a few years to live after being diagnosed with a rare form of motor neurone disease but he beat all the odds and survived to the age of 76.
People have been taking to Twitter to pay tribute to the professor.
I once asked Stephen Hawking in an interview what puzzles him the most in all the universe. "Women," he answered. He will be missed. R.I.P.— Larry King (@kingsthings) March 14, 2018
We were on earth at the same time as Stephen Hawking.
That's kind of a miraculous thing.
We breathed the same air as the man who demystified the stars.— Geraldine (@everywhereist) March 14, 2018
"Look up at the stars and not down at your feet" - Professor Stephen HawkingMarch 14, 2018
Rest In Peace Stephen Hawking, the universe thanks you.— Sofia Carson (@SofiaCarson) March 14, 2018
Sad to hear about Stephen Hawking. What a remarkable life. His contributions to science will be used as long as there are scientists, and there are many more scientists because of him. He spoke about the value and fragility of human life and civilisation and greatly enhanced both— Brian Cox (@ProfBrianCox) March 14, 2018
You can almost feel that the world is a less bright, less amazing place today. RIP Stephen Hawking.— David Schneider (@davidschneider) March 14, 2018
We've lost a great mind. “We are just an advanced breed of monkeys on a minor planet of a very average star. But we can understand the Universe. That makes us something very special.”
~ Stephen Hawking 1942 - 2018 pic.twitter.com/TdUtTQHGlY— Rebecca Corvese (@racorvese) March 14, 2018