Legendary physicist Stephen Hawking has died at age 76, according to his family. Hawking's work on theoretical physics earned him countless honors, and made him a key voice in understanding our universe.
Here are five things to know about Hawking's life and career.
1. He was diagnosed with ALS at 21
The disease forced Hawking to remain in a wheelchair and depend on a computerized voice system to communicate. According to Live Science, the average life expectancy after an ALS diagnosis is three years, with only 5% living 20 years or more. Genetics could have played a key role in Hawking's survival, Live Science reports. Studies suggest people diagnosed at a younger age tend to live much longer.
2. One of his biggest discoveries involved black holes
Working with fellow scientist Roger Penrose, he showed Albert Einstein's theory of relativity suggested space and time had a definitive beginning and end. This led to the theory that black holes aren't completely black, but emit radiation and eventually disappear.
3. His book, 'A Brief History of Time,' was a record-breaker
In 1988, Hawking published a book targeting non-scientists to help explain fundamental questions such as how the universe started and whether it will end. It set a record by spending more than five years on The Sunday Times bestseller list, and was the No. 1 all-time book on their list as of 2014.
4. He held 12 honorary degrees
Among Hawking's other accolades: In 1982, he received the Commander of the Order of the British Empire honor and was awarded the Presidential Medal of Freedom in 2009. He was also named a Fellow of The Royal Society, comprised of "the most eminent scientists, engineers and technologists from the UK and the Commonwealth," according to the society.
5. He was really worried about the future of humanity
Hawking expressed concern that the world's citizens could consume enough energy to turn Earth into a ball of fire within 600 years. That is, unless the rise of artificial intelligence doesn't get to us first.
Stephen Hawking through the years
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