World-renowned theoretical physicist Stephen Hawking died March 14 at age 76. The way his brilliant mind pondered the greatest mysteries of time and space while his body was confined to a wheelchair due to ALS made him an icon of science -- the most famous scientist since Albert Einstein. His life was memorialized in the Oscar-winning biopic The Theory of Everything. He also appeared as himself on numerous TV shows, including The Simpsons and Star Trek: The Next Generation. But the TV show he was most closely associated with wasThe Big Bang Theory, a sitcom about scientists on which he appeared numerous times.
The show's official Twitter paid tribute to Hawking on Wednesday, and cast and producers shared their own memories of Hawking on their personal accounts.
"RIP #stephenhawking," wrote Johnny Galecki, alongside a photo of the cast with Hawking. "Not only your brilliance, but your sense of humor will be sorely missed by all." He shared one of Hawking's famous quotes: "Life would be tragic if it weren't funny."
"It was truly such an honor getting to work with the incredible Stephen Hawking," wrote Kaley Cuoco. "He made us laugh and we made him laugh. His life and career workings have been many a subject matter on @thebigbangtheory__ and we are all better for it. You will be missed but the world is grateful for the knowledge and courage you leave in your path. Thank you for being an inspiration to everyone."
"As we near Pi day (3.14) I join the global community in mourning the loss of the greatest physicist of our era," Mayim Bialik wrote. "#StephenHawking is free from the physical constraints of this earthly condition we all exist in and he is soaring above us now marveling at it all. Thank you Dr. Hawking for enlightening us and blessing us with your wisdom and courage."
Hawking was a hero to the characters, and was mentioned admiringly in the series' pilot episode. He was especially beloved by physicist Sheldon (Parsons), who considered Hawking his only intellectual equal. Hawking made his first appearance in the Season 5 episode "The Hawking Excitation," when he visited Caltech and hired Howard (Simon Helberg) to perform maintenance on his wheelchair. Howard in turn introduced him to Sheldon, who of course embarrassed himself.
He also appeared (voice only) in the Season 6 episode "The Extract Obliteration," playing Words with Friends with Sheldon. He beat him soundly, and then trash-talked him straight into a black hole.
He next appeared in Season 8. Sheldon and Leonard (Galecki) published a paper that got mercilessly mocked by an internet troll, who turned out to be Hawking letting off some steam by pranking his friends. The name of that episode? "The Troll Manifestation."
He appeared the 200th episode birthday spectacular, singing "Happy Birthday" to Sheldon, and in the Season 10 episode "The Geology Elevation" in remote-controlled toy form and then via Skype signing off on the tasteless joke that is him in remote-controlled toy form. His final appearance came in the Season 11 premiere when Sheldon called him to ask for his blessing before he proposed to Amy (Mayim Bialik).
"Well, Sheldon," the physicist said, "I think you should make her finger like Saturn and put a ring on it."
RIP, Stephen Hawking. The world has lost one of its great minds, and The Big Bang Theory has lost one of its most reliably funny guest stars.
The Big Bang Theory airs Thursdays at 8/7c on CBS.
(Full disclosure: TV Guide is owned by CBS.)