Stephen Hawking has died at the age of 76, his family has said.
The British physicist was known for his work with black holes and relativity, and wrote several popular science books including A Brief History of Time.
With fellow physicist Roger Penrose, Hawking merged Einstein's theory of relativity with quantum theory to suggest that space and time would begin with the Big Bang and end in black holes. Hawking also discovered that black holes are not completely black but emit radiation and will likely eventually evaporate and disappear.
Hawking suffered from ALS (amyotrophic lateral sclerosis), a neurodegenerative disease commonly known as Lou Gehrig's Disease, which is usually fatal within a few years. He was diagnosed in 1963, when he was 21, and doctors initially only gave him a few years to live.
The disease left Hawking wheelchair-bound and paralyzed. He was able to move only a few fingers on one hand and was completely dependent on others or on technology for virtually everything -- bathing, dressing, eating, even speech.
He had at least 12 honorary degrees and was awarded the CBE in 1982. A CBE, or Commander in the Most Excellent Order of the British Empire, is considered a major honor for a British citizen and is one rank below knighthood.
Despite being a British citizen he was awarded the Presidential Medal of Freedom, the US's highest civilian honor, in 2009 by President Barack Obama.