Stephen Hawking has warned against Britain leaving the EU saying it would make us more "isolated and insular".
The theoretical physicist told Good Morning Britain that the UK needed to stay in the EU to protect its scientific research being undermined by Government austerity cuts.
Professor Hawking also warned that Britain would be "ultimately more remote from where progress is being made".
Gone are the days we could stand on our own against the world. We need to be part of a larger group of nations both for our security and our trade. The possibility of our leaving the EU has already led to a sharp fall in the pound, because the markets judge that it will damage our economy.
The Cambridge scientist said the mobility of people and grants given by the European Research Council to UK institutions were important reasons for Britons to vote to remain in the bloc on June 23.
There are two obvious reasons why we should stay in. The first is that it promotes the mobility of people. Students can come here from EU countries to study and our students can go to other EU universities. More importantly, at a level of research the exchange of people and able skills to transfer more quickly and brings new people with different ideas. Without this exchange, we would become more culturally isolated and insular and ultimately more remote from where progress is being made. The other reason is financial. The European Research Council has given large grants to UK institutions, either to foster or promote exchanges
Hawking was diagnosed with motor neurone disease in 1963 and given two years to live.
Instead, he wrote A Brief History of Time and became one of the world’s bestselling authors and most famous scientists.
He was also asked if Eddie Redmayne's portrayal of him in the film The Theory Of Everything had boosted his female fan base.
He replied: "I had many fans before Eddie Redmayne played me."
Asked if his knowledge of the universe meant he could explain the popular appeal of Donald Trump, he said it couldn't.
"He is a demagogue who seems to appeal to the lowest common denominator," he said.