The third season of the wonderfully smart and silly comedy The Big Bang Theory is even better than the first two. When Sheldon, Leonard, Howard, and Raj--the show's quartet of supreme geeks--return from their research expedition in the Arctic, Leonard and his adorable neighbor Penny fall into each other's arms. In most TV shows, losing that sexual tension would deflate the entire series, but the writers and performers of The Big Bang Theory navigate these treacherous waters with aplomb; after a weak couple of episodes, the show regains its bearings with faux tattoos, sneaky behavior modification, lessons in football, a dislocated shoulder, a trip to Switzerland, pot brownies, and the one true Ring. Guest appearances by comic book legend Stan Lee, Katee Sackhoff from Battlestar Galactica, and former Star Trek boy genius Will Wheaton as themselves are used to remarkably good effect, and Simon Helberg and Kunal Nayyar, as Howard and Raj, get better story lines than ever before. Worlds collide in Season 3! A love affair with Penny has opened a big, wide, wonderful world of romance for Leonard. But Sheldon likes the world just the way it was, thank you. All of which makes for a zany comic triangle with brainy, clueless Sheldon and practical, grounded Penny hilariously vying for the role of hypotenuse.

Originally broadcast on CBS in 2009. Special features: Big bang set tour; Big bang theory; take-out.

The electric can opener fluctuation -- The Jimmy conjecture -- The Gothowitz deviation -- The pirate solution -- The creepy candy coating corollary -- The cornhusker vortex -- The guitarist amplification -- The adhesive duck deficiency -- The vengeance formulation -- The gorilla experiment -- The maternal congruence -- The psychic vortex -- The Bozeman reaction -- The Einstein approximation -- The large Hadron collision -- The excelsior acquisition -- The precious fragmentation -- The pants alternative -- The Wheaton recurrence -- The spaghetti catalyst -- The Plimpton stimulation -- The staircase implementation -- The lunar excitation.