British physicist and cosmologist Stephen Hawking has died at the age of 76, BBC reported on Wednesday. Hawking, regarded as one of the most brilliant physicists ever, has worked on the origin of the universe and black holes and has inspired millions of people across the world.

“We are deeply saddened that our beloved father passed away today,” a statement by his children said, according to The Guardian. “He was a great scientist and an extraordinary man whose work and legacy will live on for many years. His courage and persistence with his brilliance and humour inspired people across the world.”

The statement continued: “He once said, ‘It would not be much of a universe if it wasn’t home to the people you love.’ We will miss him for ever.”

Hawking was born in Oxfordshire in January 1942. He studied physics at University College, Oxford and cosmology at Cambridge. He was diagnosed with a motor neuron disease called Lou Gehrig’s disease at the age of 21. He completed his doctorate despite doctors’ warning that he might not live for more than two years.

The disease, also known as Amyotrophic Lateral Sclerosis or ALS, gradually paralysed him, and he has used a wheelchair for decades. He used a device with a software that served as his electronic voice. Hawking was one of the longest survivors of the disease.

His bestselling books include A Brief History of Time, which sold over 10 million copies and was translated into 40 languages. He has also written popular books about the universe, including books for children with his daughter Lucy.

The 2014 biographical film The Theory of Everything, was based on Hawking’s life. Actor Eddie Redmayne, who played Hawking’s character, won an Academy Award for Best Actor.

Tributes have started to pour in for the physicist across social media, with many saying his death has left an “intellectual vacuum” in the world, and it is the loss of a “colossal mind”. Here are some reactions.