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.
All episodes — Season 3
S3 E1The Electric Can Opener Fluctuation
Sep 21, 20097.922 min
When Sheldon learns the guys tampered with his expedition data he got from the arctic, he leaves to Texas in disgrace. This results in the guys following him, which threatens Leonard's hope for some romantic time with Penny and the guys' fr
S3 E2The Jiminy Conjecture
Sep 28, 20097.421 min
Leonard and Penny struggle to recover from an awkward first hookup while Sheldon and Howard stake their best comic books on a bet to determine the species of a cricket.
S3 E3The Gothowitz Deviation
Oct 5, 20097.520 min
Howard and Raj visit a Goth nightclub to pick up women while Sheldon attempts to build a better Penny using chocolate-based behavior modification.
S3 E4The Pirate Solution
Oct 12, 20097.521 min
Raj must find a new job or be sent back to India, but Sheldon has a solution, which leaves Leonard and Penny dealing with Howard as a third wheel.
S3 E5The Creepy Candy Coating Corollary
Oct 19, 20097.721 min
After overhearing that Wil Wheaton is entering a trading-card competition, Sheldon decides to enter it himself. Meanwhile, Penny sets up one of her friends on a date with Wolowitz.
S3 E6The Cornhusker Vortex
Nov 2, 20097.120 min
Sheldon becomes Leonard's teacher in order to understand football, while an incident with flying a kite threatens Howard and Raj's friendship.
S3 E7The Guitarist Amplification
Nov 9, 20097.319 min
A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism.
S3 E8The Adhesive Duck Deficiency
Nov 16, 20098.321 min
With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.
S3 E9The Vengeance Formulation
Nov 23, 20097.819 min
After he's humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.
S3 E10The Gorilla Experiment
Dec 7, 20097.921 min
Penny gets help from Sheldon in order to understand what Leonard's work is, while Wolowitz develops a jealousy when Leonard starts hanging out with his new girlfriend.
S3 E11The Maternal Congruence
Dec 14, 20097.620 min
A Christmas visit from his mother has Leonard discovering she's kept a lot of news from him that she shares with Sheldon and worrying if she'll approve of his romance with Penny.
S3 E12The Psychic Vortex
Jan 11, 20107.919 min
Leonard is aghast to find out a secret of Penny's: she believes in psychics. Meanwhile, Sheldon tries to assist Koothrappali in picking up a girl at a university mixer.
S3 E13The Bozeman Reaction
Jan 18, 20107.720 min
When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.
S3 E14The Einstein Approximation
Feb 1, 2010819 min
Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.
S3 E15The Large Hadron Collision
Feb 8, 20107.821 min
Leonard can only bring one guest on a trip to see CERN's Large Hadron Collider (the world's largest and highest energy particle accelerator) in Switzerland on Valentine's Day.
S3 E16The Excelsior Acquisition
Mar 1, 20107.921 min
Sheldon winds up in traffic court when he gets a ticket because of Penny.
S3 E17The Precious Fragmentation
Mar 8, 20107.920 min
When the guys find a ring from "The Lord of the Rings" at a garage sale, it threatens to tear them apart.
S3 E18The Pants Alternative
Mar 22, 2010821 min
Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.
S3 E19The Wheaton Recurrence
Apr 12, 20107.521 min
A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.
S3 E20The Spaghetti Catalyst
May 3, 20107.820 min
When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.
S3 E21The Plimpton Stimulation
May 10, 20107.521 min
Leonard and Sheldon compete for the attention of a famous female physicist.
S3 E22The Staircase Implementation
May 17, 20108.420 min
Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator.
S3 E23The Lunar Excitation
May 24, 20107.820 min
While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.