Happy birthday, Stephen Hawking. The world's most famous physicist turns 71 on Tuesday, and fans everywhere are using the occasion to reflect on his contributions not only to science but also to popular culture.
Hawking, who was born in Oxford, England on January 8, 1942 , has been featured on "The Simpsons," "Star Trek," and "The Big Bang Theory" (in which he opposed Sheldon Cooper in an intense game of Words With Friends).
In addition, he's been outspoken on topics ranging from alien life to religion. Check out the slideshow below for 11 of Professor Hawking's most memorable quotations.