Episode Guide :: Season 6
|#||Episode Title||Original Air Date||User Rating|
|601||The Date Night Variable||September 27, 2012||4.5|
|With his friends on dates, Raj must face his loneliness. Also, Wolowitz is caught in an argument between Bernadette and his mom, even while he's in space, on the sixth season premiere of The Big Bang Theory.|
|602||The Decoupling Fluctuation||October 4, 2012||4.3|
|When Sheldon learns that Penny is thinking about breaking up with Leonard, he tries to intervene. Meanwhile, in space, the other astronauts pick on Howard.|
|603||The Higgs Boson Observation||October 11, 2012||4.7|
|Amy feels threatened when Sheldon hires a young female assistant, and the pressure of being in space takes its toll on Wolowitz.|
|604||The Re-Entry Minimization||October 18, 2012||4.5|
|When Wolowitz returns from space, he doesn't get the hero's welcome he expected. Meanwhile, Game Night turns into a battle of the sexes.|
|605||The Holographic Excitation||October 25, 2012||4.7|
|The gang celebrates Halloween at Stuart's comic book store. Meanwhile, Leonard seduces Penny with science.|
|606||The Extract Obliteration||November 1, 2012||4.4|
|Sheldon's relationship with Stephen Hawking is threatened over a game of "Words with Friends," and Penny secretly enrolls in a class at the local college.|
|607||The Habitation Configuration||November 8, 2012||4.6|
|Wolowitz struggles with moving out of his mother's house. Meanwhile, Sheldon is caught in the middle of an argument between Amy and Wil Wheaton.|
|608||The 43 Peculiarity||November 15, 2012||4.7|
|Howard and Raj try to get to the bottom of why Sheldon disappears every afternoon at 2:45. Meanwhile, Leonard and Penny deal with jealousy in their relationship.|
|609||The Parking Spot Escalation||November 29, 2012||4.7|
|When the University reassigns Sheldon's parking spot to Wolowitz, their fight affects the whole gang.|
|610||The Fish Guts Displacement||December 6, 2012||4.4|
|Sheldon tries to nurse a sick Amy back to health, while Wolowitz prepares for an upcoming fishing trip with his father-in-law.|
|611||The Santa Simulation||December 13, 2012||4.4|
|Sheldon revisits some Christmas memories during a game of Dungeons and Dragons, while Penny, Bernadette and Amy try to find a girl for Koothrappali when he joins the girls for ladies' night.|
|612||The Egg Salad Equivalency||January 3, 2013||4.5|
|Sheldon gets accused of sexual harassment at the University and winds up getting Leonard, Raj and Wolowitz in trouble.|
|613||The Bakersfield Expedition||January 10, 2013||4.6|
|While the guys take a road trip to a comic book convention dressed as "Star Trek: The Next Generation" characters, the girls stay home and try to interpret a comic book.|
|614||The Cooper/Kripke Inversion||January 31, 2013||4.5|
|Sheldon is forced to work with Barry Kripke and faces a crisis of confidence. Meanwhile, Howard and Raj spend $1,000 on action figures of themselves.|
|615||The Spoiler Alert Segmentation||February 7, 2013||4.5|
|When Sheldon and Leonard fight, it affects Penny and Amy's living arrangements. Meanwhile, Raj takes care of Mrs. Wolowitz while Howard is away.|
|616||The Tangible Affection Proof||February 14, 2013||4.4|
|While the guys try to give their significant others the perfect Valentine's Day, Raj and Stuart throw a "lonely people" party at the comic book store.|
|617||The Monster Isolation||February 21, 2013||4.2|
|After a terrible date, Koothrappali vows to never leave his apartment. Meanwhile, Penny actually impresses Sheldon with her acting skills.|
|618||The Contractual Obligation Implementation||March 7, 2013||4.5|
|Leonard, Sheldon and Wolowitz speak to junior high girls about careers in science. Meanwhile, Koothrappali plans a date with Lucy.|
|619||The Closet Reconfiguration||March 14, 2013||4.6|
|Howard struggles with whether or not he should open a letter from his father, and Leonard and Penny throw a "grown-up" cocktail party at the apartment.|
|620||The Tenure Turbulence||April 4, 2013||4.6|
|Leonard, Sheldon and Raj fight for tenure at the University, and the competition heats up when the girls get involved.|
|621||The Closure Alternative||April 25, 2013||4.7|
|Sheldon feels lost after one of his favorite TV shows gets canceled too soon and Amy tries to help him get over his compulsive need for closure. Meanwhile, Raj discovers a secret about his new love interest, Lucy.|
|622||The Proton Resurgence||May 2, 2013||4.7|
|Sheldon and Leonard hire Professor Proton, the host of their favorite childhood TV show, to perform. Also, Howard and Bernadette run into trouble babysitting Raj's dog.|
|623||The Love Spell Potential||May 9, 2013||4.4|
|When the girls' trip to Vegas falls through, the guys invite them to play Dungeons & Dragons, causing Sheldon and Amy's relationship to take an unexpected turn. Meanwhile, Koothrappali and Lucy go on a very awkward date.|
|624||The Bon Voyage Reaction||May 16, 2013||4.3|
|A new success for Leonard makes Sheldon very jealous and throws Penny for a loop. Meanwhile, Koothrappali pushes Lucy too far in their relationship, on the sixth season finale of The Big Bang Theory.|
The Big Bang Theory's sixth season sees Howard return from space and adjust to normal, married life on earth. Sheldon and Amy's unique relationship continues to progress, though at a slower pace than Amy wants. Leonard and Penny's relationship is business as usual, with Leonard once again proposing to Penny. Meanwhile, Raj finally meets a girl and enters a (somewhat) stable relationship, the demise of which leads to unexpected progress for Raj.
The season starts with Howard still in space, where he must figure out how to break the news to his mother that he'll be moving in with Bernadette. When Howard returns from space, he must adjust not only to married life but life back as a civilian. Initially, he struggles to move on from his space mission, bringing it up at every opportunity, as he fears it's the last great thing he will ever do.
Penny is unsure of her feelings for Leonard and briefly considers breaking up with him, though his sad puppy dogs and the intervention of a concerned Sheldon keep her in the relationship for now. As the season progresses, Leonard once again proposes and forces Penny to confront her commitment issues. Penny admits she's happy in the relationship and it's the inevitability of them getting married that scares her. Leonard tells Penny that he won't propose again and puts the ball in her court. At the end of the season, Leonard is offered the chance to go on a four month expedition to the North Sea. Though he worries about his relationship with Penny, she tells him to go on the expedition. Leonard leaves with their relationship seeming secure.
Sheldon and Amy's relationship progresses throughout the sixth season as Sheldon becomes more comfortable being in a committed relationship with Amy. When Sheldon ruins date night by inviting Raj, Amy demands a heartfelt statement of how he feels about her. Sheldon recites romantic dialogue from first Spider Man movie, which Amy says she'll take. When Amy comes down with the flu, Sheldon takes care of her. Hoping to enjoy more of Sheldon's caring side, Amy continues to pretend to be sick. After taking a cheek swab, Sheldon realizes Amy is no longer sick and, to punish her, spanks her.
When Sheldon starts lying to Barry Kripke about Amy and his sex life, Penny asks Sheldon whether he would consider having a sexual relationship with Amy. Sheldon admits he's always been uncomfortable with the sort of physical contact that comes easily to others, but says he's working on it and that it's a possibility. For Valentine's Day, Sheldon makes Amy his "In Case of Emergency" contact at the university. As the gang play Dungeons and Dragons, Amy gets upset at the group's mocking of their relationship. Amy asks Sheldon if he thinks their relationship will ever get intimate. Sheldon tells Amy he doesn't consider their relationship a joke and that he would not rule intimacy out. Sheldon then plays out the love potion scenario of the game with Amy, much to her pleasure.
After meeting at the Comic Book store, Raj starts dating Lucy. Lucy's social anxiety leads her to abandon Raj a number of times, causing him to get depressed. When Raj pushes her too hard, she dumps him leaving Raj devastated. When Penny visits Raj to check on him, Raj is unexpectedly able to talk to her without alcohol.
The Big Bang Theory's sixth season contained twenty-four episodes which aired between September 26, 2012 and May 16, 2013. During the sixth season, the show hit twenty million viewers for the first time. The Big Bang Theory averaged 18.68 million viewers during the season and was the 3rd highest-rated program on TV.