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 
When Howard needs top-level security clearance for a DoD project, his friends are interviewed by an FBI agent but one of their interviews puts Howard's job prospects in danger.
408 The 21-Second Excitation November 11, 2010  4.5 
The guys camp out to attend a screening of Raiders of the Lost Ark featuring 21 seconds of never-before-seen footage. Meanwhile, Penny hosts a slumber party with Bernadette and Amy.
409 The Boyfriend Complexity November 18, 2010  4.6 
When Penny's dad visits, she asks Leonard to lie to him and pretend they're still in a relationship. Meanwhile, Howard, Raj and Bernadette spend the night monitoring a telescope in the astrophysics lab.
410 The Alien Parasite Hypothesis December 9, 2010  4.2 
Amy experiences an unusual sensation in the company of Penny's ex, Zack. Meanwhile, Howard and Raj battle to find out who is the superhero and who is the sidekick in their friendship.
411 The Justice League Recombination December 16, 2010  4.7 
With New Year's Eve approaching, the guys invite Zack and Penny to join their Justice League group at the comic book store's annual costume party. Could this be the year they finally win?
412 The Bus Pants Utilization January 6, 2011  4.2 
When Leonard has an idea for a smartphone app, the gang get to work on developing it. Sheldon and Leonard's friendship is threatened when Sheldon tries to take over the project.
413 The Love Car Displacement January 20, 2011  4.4 
The entire gang travels to a hotel for a science conference. Their visit turns tense when Bernadette runs into her ex-boyfriend.
414 The Thespian Catalyst February 3, 2011  4.1 
Sheldon is inundated with negative feedback when he teaches a class. To improve his communication skills, Sheldon gets acting lessons from Penny. Meanwhile, Koothrappali has romantic daydreams about Howard's girlfriend, Bernadette.
415 The Benefactor Factor February 10, 2011  4.3 
Leonard must consider how far he's willing to go for science when a wealthy donor makes an intimate proposal.
416 The Cohabitation Formulation February 17, 2011  4.4 
Leonard rekindles his relationship with Raj's sister, Priya, who is back in town. Meanwhile, Howard contemplates taking his relationship with Bernadette to the next level.
417 The Toast Derivation February 24, 2011  4.6 
When the gang start spending more time at Priya's apartment, Sheldon realizes Leonard is the center of their social group, not him. Meanwhile, Penny tries to move on after seeing Leonard in a new relationship.
418 The Prestidigitation Approximation March 10, 2011  4.6 
When Priya feels threatened by Leonard spending time with Penny, she forces him to cut her out of his life. Meanwhile, Howard plays mind games with Sheldon by performing a magic trick the great scientist can not figure out.
419 The Zarnecki Incursion March 31, 2011  4.8 
After Sheldon's World of Warcraft account is hacked, the guys go on a quest to retrieve Sheldon's items and avenge Todd Zarnecki.
420 The Herb Garden Germination April 7, 2011  4.7 
After a rumor spreads that Bernadette is planning to break up with Howard, Sheldon and Amy spread their own rumors as a social experiment.
421 The Agreement Dissection April 28, 2011  4.5 
After Priya inspects the roomate agreement and disputes many of Sheldon's terms, he takes refuge with the girls.
422 The Wildebeest Implementation May 5, 2011  4.3 
Amy and Penny recruit Bernadette as a double agent when she and Howard have dinner with Leonard and Priya. Meanwhile, Raj tries out a new medication to cure his social anxiety.
423 The Engagement Reaction May 12, 2011  4.4 
After Howard finally tells his mother he's engaged to Bernadette, she ends up in the hospital. Meanwhile, it's bad news for Leonard as Penny and Priya bond.
424 The Roommate Transmogrification May 19, 2011  4.6 
Bernadette receives her Ph.D., leaving Howard as the only scientist in their group who isn't a doctor. Meanwhile, Raj becomes Sheldon's new roommate after Leonard starts staying with Priya in his apartment.

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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