Stephen Hawking died at the age of 76 on Wednesday, March 14th, 2018. The family did not give a cause of death, saying only that he died peaceably at his home in Cambridge, England.
Hawking lived for 55 years after his diagnosis of ALS at age 21. Only 5% of people with ALS survive for more than 20 years after diagnosis, so Hawking's long life is remarkable.
ALS causes the nerve cells that control voluntary muscle movements, (such as the muscles that control walking, talking, eating, and breathing) to degenerate and eventually die. Most people with ALS die from respiratory failure because the muscles that control breathing become paralyzed. People with ALS often die very peacefully while sleeping.