Episode Guide :: Season 4

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# Episode Title Original Air Date User Rating
401 The Robotic Manipulation September 23, 2010  4.6 
When Penny urges Sheldon to go on his first date, she finds herself dragged along to watch. Meanwhile, Howard finds himself in an uncomfortable position when he discovers a new use for a robotic arm.
402 The Cruciferous Vegetable Amplification September 30, 2010  4.5 
After Sheldon worries he won't live long enough to download his conciousness into a robot, he starts making changes to extend his life.
403 The Zazzy Substitution October 7, 2010  4.6 
Sheldon and Amy break up after an argument over the importance of their respective fields. Sheldon struggles to cope with the change and seeks an alternative to human companionship.
404 The Hot Troll Deviation October 14, 2010  4.3 
Howard is embarrassed when the reason behind his break-up with Bernadette is revealed. Meanwhile, Sheldon and Raj engage in a small war at work.
405 The Desperation Emanation October 21, 2010  4.3 
When Leonard realizes he's the only one without a girlfriend, he asks Howard to set him up with one of Bernadette's friends. Meanwhile, Sheldon is trying to lose his girlfriend after she asked him to meet her mother.
406 The Irish Pub Formulation October 28, 2010  4.3 
Leonard starts an affair with Raj's sister, Priya, but keeps it secret from the rest of the gang. When Sheldon gets involved, he concocts an elaborate lie.
407 The Apology Insufficiency November 4, 2010  4.4 
Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.
408 The 21-Second Excitation November 11, 2010  4.5 
While the guys camp in line for a screening, Penny and Bernadette invite Amy to her first slumber party.
409 The Boyfriend Complexity November 18, 2010  4.6 
Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.
410 The Alien Parasite Hypothesis December 9, 2010  4.2 
Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.
411 The Justice League Recombination December 16, 2010  4.7 
The guys find a "super" use for Penny's ex-boyfriend, Zack, when they enter a costume contest as the Justice League.
412 The Bus Pants Utilization January 6, 2011  4.2 
Leonard's idea for a smartphone app derails his friendship with Sheldon.
413 The Love Car Displacement January 20, 2011  4.4 
Tension runs high when everyone is staying at the same hotel for a science event and Bernadette runs into her ex-boyfriend.
414 The Thespian Catalyst February 3, 2011  4.1 
Sheldon hopes acting lessons from Penny will help him become a better teacher. Meanwhile, Koothrappali fantasizes about his best friend's girlfriend.
415 The Benefactor Factor February 10, 2011  4.3 
A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science.
416 The Cohabitation Formulation February 17, 2011  4.4 
As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.
417 The Toast Derivation February 24, 2011  4.6 
Sheldon struggles to cope when he realizes it's actually Leonard who is the center of their social group.
418 The Prestidigitation Approximation March 10, 2011  4.6 
Leonard must choose between new girlfriend Priya and his friendship with Penny. Meanwhile, Howard drives Sheldon crazy with a magic trick.
419 The Zarnecki Incursion March 31, 2011  4.8 
When someone hacks Sheldon's online game account, the guys go on a quest to find the culprit.
420 The Herb Garden Germination April 7, 2011  4.7 
Sheldon and Amy experiment on their friends by spreading gossip, while Howard takes a big step in his relationship with Bernadette.
421 The Agreement Dissection April 28, 2011  4.5 
When Priya uses her lawyer skills to pick apart the roommate agreement, the girls take Sheldon dancing.
422 The Wildebeest Implementation May 5, 2011  4.3 
Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.
423 The Engagement Reaction May 12, 2011  4.4 
When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.
424 The Roommate Transmogrification May 19, 2011  4.6 
When Bernadette receives her Ph.D., the guys take joy in reminding an emasculated Wolowitz that he is the only one in their group who isn't a doctor.

Season Recap

The Big Bang Theory's fourth season focuses on character growth as Sheldon enters a platonic relationship with Amy, Howard restarts his romance with Bernadette, and Leonard starts a serious relationship with Raj's sister Priya.

As Sheldon becomes comfortable spending more time with Amy, his "girl who is a friend but not a girlfriend", starts to spend more time with the group and forms friendship with Penny. Howard's girlfriend Bernadette also becomes a part of the group. After dating for a few months, Howard and Bernadette get engaged after he proposes.

Leonard enters a long-term relationship with Priya, Raj's sister, after she moves to Pasadena. Seeing Leonard with another women, Penny begins to regret breaking up with him. In the season finale, after a night of drinking, Raj and Penny get very close.

The Big Bang Theory's fourth season contained twenty-four episodes aired between September 23, 2010 and May 19, 2011. For its fourth season, The Big Bang Theory moved to Thursdays at 8:00 on CBS, to form a new comedy block. Although the show continued to perform well in the ratings, it fell somewhat from the third season. The new timeslot lacked the strong lead-in the show had on Mondays, with TV's then-#1 sitcom Two and a Half Men, and suffered fewer people watching TV at the earlier time. Kaley Cuoco was absent from two episodes during the season, due to a broken leg from a horseback-riding accident.

Season 4 DVD

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Relive the complete fourth season of The Big Bang Theory again with this three-disc DVD box-set. Featuring all twenty-four episodes of the show's fourth season along with never-before-seen bonus features.

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