Sheldon goes up against Stephen Hawking on 'Big Bang Theory' Michael Yarish / CBS Amy (Mayim Bialik) watches as Sheldon (Jim Parsons) plays a game of Words With Friends against Stephen Hawking. By Lesley Goldberg, The Hollywood Reporter "The Big Bang Theory's" Sheldon Cooper is about to go head to head with the only person he truly considers his equal: Stephen Hawking. Photos from THR: Behind the scenes of 'Big Bang Theory' After an awkward and less than ideal first impression during the CBS hit's fifth season, Hawking returns to the Thursday comedy this week where his friendship with the neurotic Sheldon (Jim Parsons) is threatened when a game of Words With Friends gets a little too competitive. In a clip from "The Extract Obliteration" exclusive to The Hollywood Reporter, Sheldon's not only impresses himself (naturally!) with his prowess against the theoretical physicist and cosmologist but also gets Amy (Mayim Bialik) going as well -- for completely different reasons. More from THR: 'Big Bang' enrolls 'Alphas' actor as Penny's classmate Check out the clip and hit the comments with your thoughts on how the game will shake out. "The Big Bang Theory" airs Thursdays at 8 p.m. on CBS. More in The Clicker: