ENGLAND (KGO) -- Professor Stephen Hawking died peacefully at his home in Cambridge on Tuesday evening at the age of 76, a family spokesperson says.Hawking is regarded as being one of the world's greatest modern scientists. His work in the realm of physics, space, and the theory of gravitation are among some of the most important discoveries in history.The best-known theoretical physicist of his time, Hawking wrote so lucidly of the mysteries of space, time and black holes that his book, "A Brief History of Time," became an international bestseller, making him one of science's biggest celebrities since Albert Einstein.Even though his body was attacked by amyotrophic lateral sclerosis, or ALS, when Hawking was 21, he stunned doctors by living with the normally fatal illness for more than 50 years.He also made a name for himself in pop culture with famous cameos in "Star Trek," "The Simpsons," and countless other television programs.During a 2010 interview with ABC News, Hawking was asked about the best fatherly advice he could give his children. He replied, "One, remember to look up at the stars and not down at your feet. Two, never give up work. Work gives you meaning and purpose and life is empty without it. Three, if you are lucky enough to find love, remember is it rare and don't throw it away."The world-renowned physicist's life story was portrayed in the 2014 film "The Theory of Everything."