He is well-known for his theorems in general relativity, quantum mechanics, and black hole research. His book “A Brief History of Time” had been a best seller that has sold more than 10 million copies. He had Amyotrofic Lateral Sclerosis Disease (ALS) at the age of 21 and confined to a wheelchair. A movie about his early years of life; "The Theory of Everything"
was shot in 2014.