• Air date: 21 Sep '09 23 episodes
      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.
  • List of Episodes (23)
    • 1. The Electric Can Opener Fluctuation

      21 Sep '09
      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' friendship with Sheldon.
    • 2. The Jiminy Conjecture

      28 Sep '09
      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.
    • 3. The Gothowitz Deviation

      05 Oct '09
      Howard and Raj visit a Goth nightclub to pick up women while Sheldon attempts to build a better Penny using chocolate-based behavior modification.
    • 4. The Pirate Solution

      12 Oct '09
      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.
    • 5. The Creepy Candy Coating Corollary

      19 Oct '09
      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.
    • 6. The Cornhusker Vortex

      02 Nov '09
      Sheldon becomes Leonard's teacher in order to understand football, while an incident with flying a kite threatens Howard and Raj's friendship.
    • 7. The Guitarist Amplification

      09 Nov '09
      A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism.
    • 8. The Adhesive Duck Deficiency

      16 Nov '09
      With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.
    • 9. The Vengeance Formulation

      23 Nov '09
      After he's humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.
    • 10. The Gorilla Experiment

      07 Dec '09
      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.
    • 11. The Maternal Congruence

      14 Dec '09
      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.
    • 12. The Psychic Vortex

      11 Jan '10
      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.
    • 13. The Bozeman Reaction

      18 Jan '10
      When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.
    • 14. The Einstein Approximation

      01 Feb '10
      Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.
    • 15. The Large Hadron Collision

      08 Feb '10
      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.
    • 16. The Excelsior Acquisition

      01 Mar '10
      Sheldon winds up in traffic court when he gets a ticket because of Penny.
    • 17. The Precious Fragmentation

      08 Mar '10
      When the guys find a ring from "The Lord of the Rings" at a garage sale, it threatens to tear them apart.
    • 18. The Pants Alternative

      22 Mar '10
      Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.
    • 19. The Wheaton Recurrence

      12 Apr '10
      A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.
    • 20. The Spaghetti Catalyst

      03 May '10
      When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.
    • 21. The Plimpton Stimulation

      10 May '10
      Leonard and Sheldon compete for the attention of a famous female physicist.
    • 22. The Staircase Implementation

      17 May '10
      Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator.
    • 23. The Lunar Excitation

      24 May '10
      While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.