The Big Bang Theory (season 5)

The Big Bang Theory (season 5)
Fifth season DVD cover art
Country of origin	United States
No. of episodes	24
Broadcast
Original channel	CBS
Original run	September 22, 2011 (2011-09-22) – May 10, 2012 (2012-05-10)
Home video release
DVD release
Region 1	September 11, 2012 (2012-09-11)
Region 2	September 2, 2012 (2012-09-02)
Region 4	October 3, 2012 (2012-10-03)
Season chronology
← Previous Season 4 Next → Season 6
List of The Big Bang Theory episodes

The fifth season of the American sitcom The Big Bang Theory was originally aired on CBS from September 22, 2011 to May 10, 2012 over 24 episodes.

Cast

Main article: List of The Big Bang Theory characters

• Dr. Leonard Hofstadter, portrayed by Johnny Galecki, is an experimental physicist with an IQ of 173 who received his Ph.D when he was 24 years old. He shares an apartment with colleague and friend, Sheldon Cooper. He and Penny dated at one point during the series, but they broke up during season 3. They start dating again in season 5 though their relationship is rocky.
• Dr. Sheldon Cooper, portrayed by Jim Parsons, is a theoretical physicist. Originally from East Texas, he was a child prodigy, starting college at the age of 11, right after completing the fifth grade. He received the Stevenson award when 14 and received his Ph.D when he was 16. He has an IQ of 187 and exhibits a strict adherence to routine; a lack of understanding of irony, sarcasm, and humor; and a complete lack of humility or basic empathy. He is dating Amy Farrah Fowler, when he asked her to be his girlfriend.
• Penny, portrayed by Kaley Cuoco, is the attractive, blonde neighbor who lives across the hall from Sheldon and Leonard. She has aspirations to an acting career, but has not been particularly successful thus far, only boasting a few small roles as well as a part in a hemorrhoid commercial. To pay the bills, she works as a waitress at The Cheesecake Factory. She and Leonard dated during season 3 and broke up. In the finale episode of Season 4, she was thought to have slept with Raj after drinking, but Raj revealed to her they didn't. During season 5, Penny begins to date Leonard again though their relationship is rocky. Her last name has never been revealed.
• Howard Wolowitz, portrayed by Simon Helberg, is an aerospace engineer. He is Jewish, and lives with his mother. Unlike Sheldon, Leonard, and Raj, Howard lacks a Ph.D. He defends this by pointing out that he has a master's degree in Engineering from MIT and the equipment he designs is actually built and launched into space, unlike the purely abstract work of his friends. He provides outrageous pick-up lines and fancies himself a ladies man with suitably unimpressed reactions from Penny. Though he finds that he has limited success with other women at first, he begins dating Bernadette in season 3, but they break up. They get back together in the Season 4 episode "The Hot Troll Deviation", become engaged in the episode "The Herb Garden Germination" and are married in the last episode of season 5. At the end of season 5 he went on a Russian Soyuz rocket to the International Space Station.
• Dr. Rajesh "Raj" Koothrappali, portrayed by Kunal Nayyar, is an astrophysicist originally from New Delhi, India. Known commonly as "Raj", he works alongside Sheldon exploring the string theory implications of gamma rays from dark matter annihilations. He is very shy around women and is physically unable to talk to them unless he drinks alcohol. His sister, Priya, dates Leonard in season 4 and part of season 5.
• Dr. Amy Farrah Fowler, portrayed by Mayim Bialik, is a neurobiologist. Raj and Howard meet her on an online dating site using a fake account for Sheldon. She is very similar to Sheldon, except that she is more open to social interaction and thus more susceptible to conventional behavior. She becomes close friends with Sheldon, prompting regular assertions from him that she is a girl and is his friend, but she is not his girlfriend. She finally became his girlfriend when Sheldon decides to change the course of their relationship after he becomes jealous when Amy goes out on a date with comic book store owner Stuart Bloom. Amy also forms a quirky friendship with Penny, whom Amy frequently refers to as her "bestie" and becomes Bernadette's Maid of Honor at her and Howard's wedding.
• Dr. Bernadette Rostenkowski, portrayed by Melissa Rauch, is a microbiologist. Bernadette is introduced to Howard by Penny while the two were working together at the Cheesecake Factory. At first she and Howard do not get along, as they appear to have nothing in common. When they find out that they both have overbearing mothers, however, they feel a connection. She was upgraded to main cast status in the episode "The Hot Troll Deviation", in which she and Howard revisit their previously unsuccessful relationship. She and Howard get engaged, and much comical fodder is created through similarities between Bernadette and Mrs. Wolowitz. She marries Howard at the end of season 5.

Production

The season finale depicts Howard Wolowitz traveling to the International Space Station (ISS) on board a Soyuz rocket. Thanks to technical consulting from Astronaut Mike Massimino, who also plays himself on the show, the production crew was able to put together sets that realistically depicts the Soyuz capsule and the ISS. The Soyuz capsule was constructed based on photos from NASA, the Kansas Cosmosphere for dimensions, and scavenged parts from an aerospace junkyard in Los Angeles.

Episodes

Main article: List of The Big Bang Theory episodes

Penny regrets her sleeping with Raj and has become very good friends with Leonard, Leonard breaks up with Priya, Amy pushes Sheldon in their relationship eventually becoming boyfriend and girlfriend, Penny develops her own posse and support group with the ladies, Howard prepares for his wedding and going into space to the International Space Station and Leonard asks Penny out as they begin "Leonard and Penny 2.0".

The Big Bang Theory season 5 episodes

No. in series	No. in season	Title	Directed by	Written by	Original air date	Prod. code	U.S. viewers (millions)
88	1	"The Skank Reflex Analysis"	Mark Cendrowski	Story: Eric Kaplan, Maria Ferrari & Anthony Del Broccolo Teleplay: Chuck Lorre, Bill Prady & Steven Molaro	September 22, 2011 (2011-09-22)	3X6851	14.30
Raj finds himself in hot water with Leonard and Howard after supposedly sleeping with Penny and the latter discovering his fantasies about Bernadette (who also became angry at Raj because of his fantasies, and now has to contend with Howard's feeling of distrust of her as a result). Raj and Penny later talk and it turns out they didn't have sex because Raj ejaculated prematurely when Penny tried to help him put on a condom. Nonetheless, Penny feels that this has damaged her relationship with the guys permanently and decides to move back to Nebraska, as she has not had any worthwhile acting jobs since moving to Pasadena. When she comes over to apologize and announce her intention to move, she gets a call from her agent, informing her that she got a part in a hemorrhoids commercial, prompting her to scrap her plans. Meanwhile, after trying to figure out what Penny meant by "It's not what it looks like." (from the season 4 finale), Sheldon has appointed himself the captain of the guys' paintball team. When they are at another of the university's tournaments where they fight against other departments, their team falls apart because of Leonard, Howard and Raj's lack of enthusiasm due to everything that has gone on with Penny. Sheldon, blaming himself, puts down his paintball gun and walks outside, proclaiming that geology isn't a real science. Following that, he is promptly shot several times by the geology team. Leonard, Howard, and Raj immediately rush out to avenge Sheldon's "sacrifice" and even manage to claim the victory for the physics team. Recurring character: Christine Baranski as Dr. Beverly Hofstadter Title reference: Amy's term for Penny's promiscuous behavior that is responsible for releasing dopamine. Amy also remarks this as being similar to Catherine the Great having sex with a horse.
89	2	"The Infestation Hypothesis"	Mark Cendrowski	Story: Bill Prady, Steven Molaro & Maria Ferrari Teleplay: Chuck Lorre, Jim Reynolds & Steve Holland	September 22, 2011 (2011-09-22)	3X6852	14.94
Priya has returned to India and she and Leonard are attempting a long-distance relationship. Their first time having cybersex is ruined when Leonard's screen freezes. Leonard then takes advice from Howard on how to maintain such a relationship and then prepares to perform one of the things he taught him, but is humiliated to learn that Priya's parents are sitting beside her. Meanwhile, Penny picks up a new chair, which at first Sheldon thoroughly likes until he finds out that she picked it up off the curb. He begins to harass Penny to dispose of it, resulting in many rejections. Sheldon then enlists Amy to try and coax Penny to get rid of it, but this only alienates Amy from Penny. Fearing her friendship with Penny is over, Amy sits on the chair to show her loyalty. She is then bitten by something moving in the chair, causing her and Penny to flee the apartment. Penny then tosses the chair, but Howard and Raj find it and bring it up to Leonard and Sheldon's apartment, as Raj doesn't want to sit on the floor all the time. Unbeknownst to them, the unidentified creature is seen moving again while they carry the chair up to the apartment. Recurring characters: Aarti Mann as Priya Koothrappali, Brian George as Dr. V. M. Koorthrappali, and Alice Amter as Mrs. Koothrappalli Absent: Melissa Rauch as Bernadette Title reference: Sheldon worrying over what hazards Penny's chair might contain.
90	3	"The Pulled Groin Extrapolation"	Mark Cendrowski	Story: Chuck Lorre, Eric Kaplan & Jim Reynolds Teleplay: Bill Prady, Steven Molaro & Dave Goetsch	September 29, 2011 (2011-09-29)	3X6853	14.74
After the entire group leaves Leonard and Sheldon's apartment following dinner, Amy stays behind while Leonard works. Her presence makes Leonard uncomfortable, telling him that she has been told she has a tendency to overstay her welcome. She later asks Leonard to accompany her to a friend's wedding, as Sheldon's past behavior at such gatherings makes him a poor date. At the wedding, Leonard is depressed at the state of his relationship with Priya, to which Amy retorts that her boyfriend is at home playing with model trains, and convinces him to dance with her. Arriving home, Leonard is revealed to have strained a muscle in his groin, which was eased by ice given to him by Amy. When Leonard later ends their evening together by kissing her on the cheek, Amy fears Leonard has fallen in love with her, and goes to Penny for advice. Amy sends Leonard an email clarifying that she does not have feelings for him, but when Leonard relates the events of the wedding to Sheldon the next morning, including the incident with his pulled groin, Sheldon incorrectly understands that they had sex, and becomes jealous and hits Leonard, saying, "She is not for you! Not for you!" Meanwhile, after Bernadette tells Howard that she refuses to move in with him and his mother after they get married, he asks her to stay over for the weekend as a trial run. Bernadette agrees, but is horrified at aspects of Howard's relationship with his mother.When Bernadette serves Howard breakfast in bed that morning, she says that communication with her mother is a bit tricky, on account of how different the two women are, and launches into a back-and-forth series of exchanges with Mrs. Wolowitz in which Bernadette imitates Mrs. Wolowitz's voice and accent perfectly. Recurring character: Carol Ann Susi as Mrs. Wolowitz Title reference: Sheldon hitting Leonard after misinterpreting Leonard's pulled groin was caused by having sex with Amy.
91	4	"The Wiggly Finger Catalyst"	Mark Cendrowski	Story: Chuck Lorre, Dave Goetsch & Anthony Del Broccolo Teleplay: Bill Prady, Steven Molaro & Steve Holland	October 6, 2011 (2011-10-06)	3X6854	13.92
Penny sets Raj up with her deaf friend, Emily (Katie Leclerc), for whom his selective mutism is no longer an issue. He immediately takes a liking to her, although he requires Howard as a communicator at first. When Howard and Penny realize that Emily is exploiting Raj for all the expensive things he buys her with his parents' wealth (which Sheldon reveals to the others is far greater than they all previously realized), they attempt to talk to her. Howard is distracted by a couple of females, loses the trail of the conversation and ends up asking her directly if she was a gold-digger. She is very offended at the intrusion. Penny then contacts Raj's parents, who threaten to cut off his allowance if he does not break up with her. When Raj chooses to remain with Emily, and tells her that they're going to return the expensive gifts he bought her, Emily breaks up with him. After commiserating with his friends at the Cheesecake Factory, they leave the bill with Raj, and Penny warns him not to be cheap with his tip, as they now know how much money he has. Meanwhile, after playing Dungeons & Dragons with the others, Sheldon decides to let the game's dice make trivial decisions for him from now on, so his mind is freed up for more important things. Although this allows him to get some important work done more efficiently, it also results in eating things he wouldn't normally eat, and other odd decisions, such as growing a mustache. Guest star: Katie Leclerc as Emily Recurring characters: Brian George as Dr. V. M. Koorthrappali and Alice Amter as Mrs. Koothrappalli. Title reference: Raj and Howard's use of sign language to communicate with Emily.
92	5	"The Russian Rocket Reaction"	Mark Cendrowski	Story: Bill Prady, Steven Molaro & Jim Reynolds Teleplay: Chuck Lorre, Eric Kaplan & Maria Ferrari	October 13, 2011 (2011-10-13)	3X6855	13.58
While Leonard and Sheldon are purchasing a fantasy sword at the comic book store, Wil Wheaton walks in, purchases a comic from Stuart, and then invites him, Leonard and Sheldon to a party at his house. When Leonard accepts, Sheldon, who regards Wheaton as one of his mortal enemies, sees this as an act of betrayal on Leonard's part. He begins treating Leonard as a Schroedinger's Friend: being amicable one moment and hostile the next, the final outcome to be determined when Leonard does or does not go to the party. Sheldon relents when told that Brent Spiner is at the party, and attends. At the party, Wheaton gives him a signed, mint-in-box Wesley Crusher doll (whose denial to Sheldon years earlier at a convention at which Wheaton failed to appear was the origin of Sheldon's animosity towards Wheaton, as explained in "The Creepy Candy Coating Corollary"), bringing an end to Sheldon's enmity with him. When Brent Spiner impulsively rips open the package, however, an infuriated Sheldon places Spiner on his mortal enemies list. Meanwhile Howard is ecstatic to learn he will be traveling to the International Space Station as a payload specialist to assist in the implementation of a deep space telescope designed by his engineering team, but Bernadette, who worries about Howard traveling into space, and is angered that he did not discuss it with her before making his announcement, angers him by telling his mother, who forbids him from going. Guest star: Brent Spiner as himself Recurring characters: Wil Wheaton as himself, Kevin Sussman as Stuart Bloom, and Carol Ann Susi as Mrs. Wolowitz Title reference: Bernadette's reaction to Howard planning to fly to the International Space Station with a Russian Soyuz rocket.
93	6	"The Rhinitis Revelation"	Howard Murray	Story: Chuck Lorre, Eric Kaplan & Steve Holland Teleplay: Bill Prady, Steven Molaro & Jim Reynolds	October 20, 2011 (2011-10-20)	3X6856	14.93
Sheldon's mother, Mary (Laurie Metcalf) is in town for a visit, but Sheldon becomes irate with her when she decides to go sightseeing with his friends instead of going with him to embarrass Nobel Prize laureate Saul Perlmutter at a lecture. Amy counsels Sheldon that while he is a genius, his emotional reactions to his mother's ignoring him are no different from that of any other human being, and that the less intelligent might be able to handle their emotions better by not over thinking them. Sheldon, after being caught in the rain, returns home with a common cold, prompting his mother to nurse him back to health. Recurring character: Laurie Metcalf as Mary Cooper Absent: Melissa Rauch as Bernadette Title reference: Sheldon comes down with a case of Rhinitis after discovering the truth of his emotional development.
94	7	"The Good Guy Fluctuation"	Mark Cendrowski	Story: Chuck Lorre, Dave Goetsch & Maria Ferrari Teleplay: Bill Prady, Steven Molaro & Steve Holland	October 27, 2011 (2011-10-27)	3X6857	14.54
A successful Halloween prank from the group enrages Sheldon, who promptly starts working on his revenge. His efforts all end up being fruitless, as Sheldon pranks are too obvious, prosaic, and hampered by his inability to effect guile or deception. He eventually seems to have success in tricking Howard with an electric handshake. When Howard breaks down because of a heart condition, Sheldon is terrified. Bernadette orders him to inject adrenaline into Howard's heart. After doing so, he is astonished to find out that it all was a ruse by Howard and Bernadette. Meanwhile, Leonard meets a good-looking female comic book enthusiast called Alice (Courtney Ford), but is torn by whether to be loyal to Priya or cheat on her with Alice. When on a date in the middle of a romantic embrace with Alice, he confesses that he has a girlfriend. Alice thinks he's just another jerk and throws him out. When Leonard subsequently relates these events to Priya, she appears to accept it as a harmless mistake, but when she reveals that she had sex with her ex-boyfriend a couple of weeks ago, Leonard becomes upset and ends the call. As he sits on the living room couch, Sheldon leaps out from under the couch cushions in zombie face paint, scaring Leonard. He triumphantly shouts "Bazinga, punk! Now we're even!" Recurring characters: Aarti Mann as Priya Koothrappali and Kevin Sussman as Stuart Bloom Absent: Mayim Bialik as Amy Title reference: Leonard torn between being loyal to Priya or having an affair with Alice. When confessing to Alice, Leonard calls "being a good guy" his "superpower".
95	8	"The Isolation Permutation"	Mark Cendrowski	Story: Chuck Lorre, Eric Kaplan & Tara Hernandez Teleplay: Bill Prady, Steven Molaro & Steve Holland	November 3, 2011 (2011-11-03)	3X6858	15.98
Amy is hurt to discover that Bernadette and Penny tried on bridesmaid dresses without her. When Sheldon tries to counsel her, she requests that they have sex, but they settle on cuddling, an experience Sheldon dislikes. When Penny and Bernadette learn of this, they are guilt-stricken, and attempt to apologize, but Amy is unyielding. Leonard and Sheldon later pick up a drunk Amy from the parking lot of a liquor store. She tells them that she learned from Penny to drown her sorrows in wine, and asks Sheldon to have sex with her. Penny and Bernadette try to apologize to her again. Bernadette finally succeeds by asking Amy to be her maid of honor, which she joyfully accepts because of all the wedding work to come (including Bernadette's bridal shower and bachelorette party). The episode ends with Amy taking a video of them trying on dresses together also catching Penny in her underwear. Title reference: Penny and Bernadette isolating Amy by going wedding dress shopping without her.
96	9	"The Ornithophobia Diffusion"	Mark Cendrowski	Story: Chuck Lorre, Dave Goetsch & Anthony Del Broccolo Teleplay: Bill Prady, Steven Molaro & Eric Kaplan	November 10, 2011 (2011-11-10)	3X6859	15.89
Leonard and Penny decide to go to the movies as friends. However Leonard refuses to exhibit the familiar deference to her that he formerly displayed to her as her boyfriend to make her amenable to sex, insisting that they see a documentary on dams instead of a Jennifer Aniston movie and making Penny pay for tickets and food. Irritated by Leonard's behavior, Penny begins to flirt with Kevin, a geeky screenwriter. Leonard retaliates by flirting with a woman named Laura. Penny then sabotages Leonard's meeting with Laura, leading to a fight between Leonard and Penny before they decide to return home. Outside the apartment, they apologise to each other and Penny tells Leonard that she actually liked his new-found confidence, but he misses this opportunity by defaulting to his usual deference. Meanwhile, Sheldon, who suffers from ornithophobia, is afraid and upset when he sees that a Black-throated Magpie-Jay had made a nest in his apartment windowsill. He tries all means to get rid of the bird, including mimicking a cat's meow and making Howard design an ultrasonic machine to scare away the bird, all of which fail. Eventually he decides to shoo the bird away using a broom, but when he opens the window to do so, the bird enters the apartment. A terrified Sheldon then asks Amy and Bernadette to get rid of the bird, but instead they make him overcome his fear by making him touch the bird. Sheldon soon grows fond of it, calls it "Lovey-Dovey" and decides to keep it as a pet. However, when Sheldon opens the window to shift the bird's nest to his apartment, the bird flies away, to his dismay. The episode ends with Sheldon revealing to Leonard that he found an egg in the nest and intends to become "a mommy". Title reference: Sheldon overcoming his fear of birds, most commonly referred to as "ornithophobia".
97	10	"The Flaming Spittoon Acquisition"	Mark Cendrowski	Story: Chuck Lorre, Steven Molaro & Dave Goetsch Teleplay: Bill Prady, Jim Reynolds & Steve Holland	November 17, 2011 (2011-11-17)	3X6860	15.05
When Amy visits the comic book store with Sheldon, Stuart, after inquiring about the state of her relationship with Sheldon, asks her out. When Sheldon later learns that Amy and Stuart are out on a date, Sheldon becomes jealous and asks Penny to go out on a date. After talking to Penny, he interrupts Amy and Stuart on their date, and asks Amy to be his girlfriend, which she gladly accepts. When Sheldon presents her a "relationship agreement", she is delighted and calls it very romantic, though she later feels that she should have consulted a lawyer over the agreement's stipulation that as a girlfriend, she must take care of her boyfriend's injuries. Meanwhile, the guys find out that a new expansion pack for Mystic Warlords of Ka'a called Wild West and Witches has come out, which they initially turn down because of its theme and the price, but eventually buy after an argument about who would win in a fight between Billy the Kid and the Wizard of the North. Leonard also tries to return the expansion pack, but Raj buys the Deluxe Limited Edition of the pack in a collector's tin. Leonard once again turns it down, but then ends up buying it, while being annoyed with himself for doing so. Recurring character: Kevin Sussman as Stuart Bloom and Josh Brener as Dale Title reference: One of the new cards in the new Mystic Warlords of Ka'a expansion pack.
98	11	"The Speckerman Recurrence"	Anthony Rich	Story: Chuck Lorre, Bill Prady & Steve Holland Teleplay: Steven Molaro, Eric Kaplan & Anthony Del Broccolo	December 8, 2011 (2011-12-08)	3X6861	14.02
Leonard is contacted by Jimmy Speckerman (Lance Barber), a former high-school classmate who bullied him on a regular basis, with a potential business proposition. When they meet, Speckerman greets Leonard like an old friend. He then proposes to make glasses that turn all movies into 3D. Sheldon confronts Speckerman for Leonard presenting him with Leonard’s complaint list. Speckerman is shocked by the list and later arrives at Leonard's apartment drunk and apologetic. The next morning he belittles Leonard’s grudge causing Leonard to order him out of the apartment. After being shoved by Leonard, Speckerman chases Leonard and Sheldon out of their own apartment. Meanwhile, Amy and Bernadette, while hanging out in Penny's apartment, discuss their own trouble with bullies. Penny mentions having pulled a prank on a smart girl in school by tying her up and leaving her in a cornfield, revealing that she was a bully herself. After trying to make amends by calling the people she bullied to apologize, she is rebuffed in the attempt. Instead she decides to give away some of her clothes that she no longer wants to make herself feel better. While dropping off her clothes, Penny takes some of the used clothes that she likes from the donation container, only to go back and return them the next day. Bernadette, however, runs back to collect a pair of shoes she liked, justifying her actions by the fact that she works at a soup kitchen. Guest star: Lance Barber as Jimmy Speckerman Title reference: Jimmy Speckerman—Leonard's high-school bully re-entering his life.
99	12	"The Shiny Trinket Maneuver"	Mark Cendrowski	Story: Chuck Lorre, Steve Holland & Tara Hernandez Teleplay: Bill Prady, Steven Molaro & Jim Reynolds	January 12, 2012 (2012-01-12)	3X6862	16.13
Amy and Sheldon's relationship hits a snag when she reveals that an article she wrote is on the front cover of a prestigious science journal, but he simply fails to respond, causing her to leave in a huff. After being questioned by Penny, he reveals that it is because he cares nothing for biology that he didn't congratulate her. Sheldon tells Penny he can't fake smile as the smile he uses is for when he sees a koala, which Amy has seen. Over a game of Red Dead Redemption with Leonard, Sheldon tries to think of a way to make it up to Amy, and Leonard suggests that he buy something for her. Sheldon agrees and purchases a diamond tiara from a jewelry store (and a pocket watch for himself) with the help of Penny. Amy, initially insulted, becomes ecstatic when she sees the tiara and forgives him at once, exclaiming "I'm a princess!", giving a big kiss and hugging him tightly. Meanwhile, Howard and Bernadette's relationship also hits a snag when, while giving a magic show at a child's birthday party, Bernadette reveals she doesn't like children (having been forced to look after her brothers and sisters when she was younger). This upsets Howard, who wants children of his own, and whose mother has been nagging him to give her a grandchild for years. He even contemplates breaking up with Bernadette, although Leonard immediately advises against it. Eventually, Bernadette suggests that, as she earns more than him, she work and Howard look after the kids. Howard, though slightly perturbed by her remark and the prospect of having to look after children on his own, agrees. Recurring character: Carol Ann Susi as Mrs. Wolowitz Note: Mayim Bialik submitted this episode for consideration due to her nomination for the Primetime Emmy Award for Outstanding Supporting Actress in a Comedy Series at the 64th Primetime Emmy Awards. Title reference: Sheldon buying Amy a tiara at the jewelry store, in an attempt to make her forgive him.
100	13	"The Recombination Hypothesis"	Mark Cendrowski	Story: Chuck Lorre Teleplay: Bill Prady & Steven Molaro	January 19, 2012 (2012-01-19)	3X6863	15.83
Upon arriving home, Sheldon discovers that the cutout of Mr. Spock he ordered is of Zachary Quinto, not Leonard Nimoy. As he gripes about this, Leonard notices Penny across the hall, and spontaneously asks her out on a date. Penny complains to Amy and Bernadette about being nervous over their date. Their dinner starts well, but soon goes sour when Leonard insists on over-analyzing their relationship. He comes home in a bad mood, causing Howard and Raj to assume he and Penny are on the outs. However, that night, Penny invites him over via text, and, after warning him not to talk, they have sex. They agree to keep their relationship secret. When everyone has dinner at the Cheesecake Factory, Leonard overplays his fake annoyance, genuinely angering Penny. They have a late-night argument, followed by more sex. Leonard tells Penny that he cannot imagine this ending well, to which she responds that it's because he over-thinks things. The scene shifts back to the hallway, with Sheldon still grousing about Spock – the whole episode was in Leonard's imagination. Realizing he does over-think things, he marches into Penny's apartment and asks her out. She asks if he's thought this over, and he replies that he has, but that they should go anyway. She agrees as a smile comes to her face. The episode ends with Penny preparing for her date with Amy and Bernadette. When asked a question, though, she is distractedly imagining herself very pregnant and marrying Leonard, which reminds her to stop by the drugstore before the date. Title reference: Leonard contemplating the ramifications of asking Penny out on a date.
101	14	"The Beta Test Initiation"	Mark Cendrowski	Story: Chuck Lorre, Steven Molaro & Eric Kaplan Teleplay: Bill Prady, Dave Goetsch & Maria Ferrari	January 26, 2012 (2012-01-26)	3X6864	16.13
Leonard and Penny have started dating again. Penny wants to take the relationship slow. Anxious to avoid the mistakes of last time, Leonard suggests they have an Alpha test relationship: rather than getting angry with each other, they'll simply report any 'bugs' they discover and fix them. This goes poorly due to Leonard giving Penny an insultingly long list of her faults, although she remains calm about it. When he tries to patch things up by taking her target shooting, he accidentally shoots himself in the shoe, barely missing his toe. Afterwards, Penny reassures Leonard that their relationship is progressing smoothly. Meanwhile, Sheldon and Amy start a podcast series about flags. Amy makes suggestions about their telecast which Sheldon accepts out of character indicating a close bond between them. Raj gets an iPhone 4S and falls in love with its virtual assistant, Siri. He takes Siri on dates including going out for coffee and a dinner party with Howard and Bernadette which the two of them find very creepy. Kripke reveals he has the same model phone, but his speech impediment (rhotacism) leads to Siri making some humorous errors. He dreams about meeting the woman behind the voice and cannot speak to her directly. Guest star: Becky O'Donohue as Siri Recurring character: John Ross Bowie as Barry Kripke Title reference: Leonard proposes to re-establish the relationship with Penny as an alpha test experiment to iron out all the bugs in their relationship, but Penny mistakenly calls it a beta test.
102	15	"The Friendship Contraction"	Mark Cendrowski	Story: Chuck Lorre, Eric Kaplan & Jim Reynolds Teleplay: Bill Prady, Steven Molaro & Steve Holland	February 2, 2012 (2012-02-02)	3X6865	16.54
Sheldon keeps Leonard awake all night with a quarterly disaster preparedness drill (with Leonard failing it). The next day, a tired Leonard refuses to take Sheldon to the dentist as he wants to sleep, despite Sheldon's protests. Leonard then invokes Section 209 in the Roommate Agreement; this involves termination of Leonard and Sheldon's friendship and would reduce them to mere acquaintances, freeing Leonard from his obligations to Sheldon. It soon turns out that Sheldon is stranded without Leonard, as none of his other friends are willing to help him. One night, when the power goes off, Sheldon tries to win back Leonard by showing him an extensive emergency kit, but the latter prefers to go over to Penny's apartment for wine. Leonard and Penny are about to make out when Sheldon comes over and offers Leonard s'mores and water distilled from urine if he accepts him as a friend again. Leonard refuses, but Penny feels sorry for Sheldon and advises Leonard to reconcile with him. Leonard then tells Sheldon that he would accept him as a friend again if he appreciates what he does for him once in a while. Sheldon then offers to celebrate "Leonard's Day" once in a year, where Leonard's achievements would be acknowledged, but all that he would get is a greeting card. Leonard agrees and reconciles with Sheldon. It soon turns out that it was Sheldon who had cut the power to the entire apartment. Meanwhile, Howard is anxious as to what nickname the other astronauts in his space mission are going to give him. Raj attempts to get them to choose the nickname "Rocket Man" (an Elton John song) by having Howard change his ringtone to that song and then calling him during a conference call with Mike Massimino. This backfires as Howard's mother yells that his Froot Loops are getting soggy, and he ends up with "Froot Loops" as his new moniker. Guest star: Mike Massimino as himself Recurring characters: Kevin Sussman as Stuart Bloom and Carol Ann Susi as Mrs. Wolowitz Note: This episode was the most watched episode of season 5, with 16.54 million viewers. Title reference: Leonard and Sheldon's relationship is reduced from friends to mere acquaintances.
103	16	"The Vacation Solution"	Mark Cendrowski	Story: Chuck Lorre, Anthony Del Broccolo & Tara Hernandez Teleplay: Bill Prady, Steven Molaro & Maria Ferrari	February 9, 2012 (2012-02-09)	3X6866	16.21
When Sheldon is forced to take a vacation by President Siebert, he decides to spend it by working at Amy's neurobiology lab. However, he eschews doing basic work such as cleaning beakers and counting bacterial spores, and when Amy eventually cedes to his demand to perform brain dissection, he faints after accidentally cutting his thumb. Meanwhile, Howard learns to his dismay that Bernadette's father wants Howard to sign a prenuptial agreement. Penny tells him that he is lucky to have Bernadette and should sign the agreement. Penny also scolds Sheldon for fainting at the sight of blood. Sheldon subsequently apologizes to Amy for his behavior the previous day, while Howard tells Bernadette that he will talk to her father about the prenuptial agreement. But when Bernadette explains that her father still carries his police revolver and is a far-right extremist who hates Jews, Howard decides to put off the discussion until after he is aboard the International Space Station. Recurring character: Joshua Malina as President Siebert Title reference: Suddenly forced to take his vacation time, Sheldon decides to go to work with Amy in her biology lab.
104	17	"The Rothman Disintegration"	Mark Cendrowski	Story: Chuck Lorre, Bill Prady & Steve Holland Teleplay: Steven Molaro, Eric Kaplan & Jim Reynolds	February 16, 2012 (2012-02-16)	3X6867	15.65
The deranged Professor Rothman is forced to retire, leaving his office vacant. Both Sheldon and Barry Kripke fight for the office and bring it to the attention of President Siebert, who is not interested in their argument. Sheldon and Kripke decide to settle their argument once and for all by playing a game of basketball, as both are bad at sports. However it soon becomes evident that both don't know how to play it, and the challenge is reduced to who bounces the ball highest. Sheldon wins the challenge and gets the office. He enjoys his new office until he finds out that the thermostat for the air conditioner is in another room where its occupant is experiencing hot flashes, the upstairs geology department is too noisy and the mockingbirds are "completely out-of-tune" with the wind chimes. He also has to deal with the constant presence of a naked Professor Rothman. Finally, his curiousity gets the better of him and he gets his head stuck in a hole in the wall, which Leonard photographs and posts online. Meanwhile, Penny receives a gift from Amy, a $3,000 painting of the two of them, which she does not find flattering and she removes it from the wall once Amy leaves her apartment. However she returns immediately and on seeing the painting removed from the wall, she becomes upset. Penny consoles Amy by saying that she removed the painting because Bernadette was jealous on seeing it. Later, Penny hangs the painting on the "fourth wall". Guest star: Lynn Phillip Seibel as Professor Rothman Recurring characters: John Ross Bowie as Barry Kripke and Joshua Malina as President Siebert Title reference: The disintegration of Professor Rothman's mental state.
105	18	"The Werewolf Transformation"	Mark Cendrowski	Story: Chuck Lorre, Todd Craig & Gary Torvinen Teleplay: Bill Prady, Steven Molaro, Jim Reynolds & Maria Ferrari	February 23, 2012 (2012-02-23)	3X6868	16.20
Sheldon's regular barber Mr. D'Onofrio has been hospitalized in a coma and he refuses to get his hair cut from his nephew Angelo. Penny offers to cut Sheldon's hair as she used to cut her brother's hair, but he refuses. A week later, Sheldon has still not got his haircut and on Penny's advice, decides to relax his regimented lifestyle and "embrace the chaos". He begins to do things he never used to do before, like wearing his Tuesday pajamas on Thursday night and playing bongos at 3 am. This wakes Leonard and Penny, who plead with Sheldon to stop playing the bongos, to no avail, and he leaves the apartment still playing the bongos. The next morning Penny and Leonard find Sheldon asleep on Amy’s couch. With Amy's vote of confidence, Sheldon agrees to let Penny cut his hair. Sheldon is impressed with the way Penny had cut his hair, but when she is trimming his neck, she shaves off the back of his head accidentally. Meanwhile, Howard goes for astronaut training in Houston. He confides to Bernadette via webcam his experiences in training, which involved vomiting during Zero-G training and having a horrible survival test. Bernadette takes pity on Howard and rushes to Houston to take care of him, where she quickly finds out that his mother is already there to take care of him. Also, Penny beats Leonard at chess despite not knowing the names of any of the pieces. This mildly annoys Leonard, who is reluctant to tell Penny that she had won, however this irritation is soon overshadowed by Sheldon's later behavior. Guest star: Peter Onorati as Angelo Recurring characters: Carol Ann Susi as Mrs. Wolowitz and Vernee Watson as Althea Note: When Penny attempts to convince Sheldon to let her cut his hair by citing milestones in their friendship, she notes that he has even seen her naked, a reference to the third season episode "The Adhesive Duck Deficiency". Note: Jim Parsons submitted this episode for consideration due to his nomination for the Primetime Emmy Award for Outstanding Lead Actor in a Comedy Series at the 64th Primetime Emmy Awards. Title reference: The transformation in Sheldon's routine and attitude, when his comatose barber is unable to cut his hair.
106	19	"The Weekend Vortex"	Mark Cendrowski	Story: Chuck Lorre, Bill Prady & Tara Hernandez Teleplay: Steven Molaro, Eric Kaplan & Steve Holland	March 8, 2012 (2012-03-08)	3X6869	15.04
Raj suggests the four guys have a Star Wars: The Old Republic online video game marathon; however, Sheldon had promised to attend a birthday party for Amy's aunt. Sheldon wants to stay, but agrees to stick with his commitment to Amy. Howard on the other hand invites Bernadette to join their marathon. Sheldon tries unsuccessfully to get Penny to talk to Amy into changing her mind. When Amy picks up Sheldon, he has his computer and plans to play along remotely. Amy is unhappy, but tells him to go join the gang. Later she shows up at Penny's confiding about her boyfriend. She tells Penny that she wanted to show her family that she had a real boyfriend and not an imaginary one, as she had concocted in the past. They decide for Amy to make a scene in Sheldon’s apartment. During the encounter, Raj stands up and complains that he wanted the guys to get together like they used to before everyone else had girlfriends. Raj then reveals his weekend plan was concocted because he is the only one of the four guys who doesn't have a girlfriend. Penny tells Amy that that is the way a girl makes a scene, and the girls leave the guys alone. The next day, the game fest ends when Howard’s mother bangs on the door demanding an explanation for Howard's weekend-long absence. Recurring characters: Carol Ann Susi as Mrs. Wolowitz and Kevin Sussman as Stuart Bloom Title reference: The girls interfering in the guys' plan to play Star Wars: The Old Republic for an entire weekend.
107	20	"The Transporter Malfunction"	Mark Cendrowski	Story: Chuck Lorre, Bill Prady & Maria Ferrari Teleplay: Steven Molaro, Jim Reynolds & Steve Holland	March 29, 2012 (2012-03-29)	3X6870	13.96
After Sheldon complains about Penny's constant mooching of their food, she buys him and Leonard each a mint-conditioned vintage Star Trek transporter from 1975. She is disappointed when they both refuse to take them out of their boxes since they want to preserve the toy's value. That night, Sheldon has a dream where his Spock action figure (voiced by Leonard Nimoy) tells him to take out the transporter and use it. When Sheldon does this however, he breaks his transporter accidentally. He then changes his broken toy for Leonard’s toy, figuring that he will never find out since he doesn't plan to open his. Later, Sheldon has a nightmare where his Spock action figure chastises him for switching the two transporters. When Leonard decides to play with his toy since it is a gift from his girlfriend, Sheldon admits to breaking his toy and switching it with Leonard's. Meanwhile, faced with the prospect of attending Howard's wedding alone, Raj tells his parents to find a suitable girl for him. He meets the prospective bride, Lakshmi, in a restaurant, and both hit it off immediately. It soon turns out that Lakshmi is a lesbian and accepted to meet Raj as it is difficult to come out in Indian culture, but nevertheless decides to marry him as she thinks he is gay. Raj too contemplates marrying her, despite the fact that he is never going to have sex with her, and rebuffs Howard's advice to find some other girl. Finally, Howard and Bernadette gift Raj a Yorkie puppy to cheer him up and make him forget about Lakshmi. Guest stars: Chriselle Almeida as Lakshmi and Leonard Nimoy as Spock (voice) Recurring characters: Brian George as Dr. V. M. Koothrappali and Alice Amter as Mrs. Koothrappalli Absent: Mayim Bialik as Amy Note: This is the first time that Leonard Nimoy has guest-starred in the series. The producers of the show had been trying for years to get Nimoy, who has largely retired from on-camera acting, to appear on the show. Title reference: Sheldon breaking his Star Trek transporter collectible, after electing to open it.
108	21	"The Hawking Excitation"	Mark Cendrowski	Story: Bill Prady, Steven Molaro & Steve Holland Teleplay: Chuck Lorre, Eric Kaplan & Maria Ferrari	April 5, 2012 (2012-04-05)	3X6871	13.29
Howard is hired to maintain Stephen Hawking's wheelchair while he is lecturing at Caltech. Howard plans to bring Sheldon along to meet his idol until Sheldon insults him again about his physics knowledge. After endless pleading, Howard agrees to give Stephen Hawking Sheldon’s latest paper on the Higgs boson, but only if Sheldon performs several tasks for him. Howard makes Sheldon clean his large collection of belt buckles, walk through the Caltech cafeteria in a French maid costume and do his laundry. Bernadette learns what Howard is doing, and tells him to stop until she remembers she was going to go dress shopping with Mrs. Wolowitz and suggests the last task for Sheldon is to go in her place. While shopping for the dresses, Sheldon is forced to go into the women's dressing room and squeeze Mrs. Wolowitz into the dress as it does not fit her. Before agreeing to give Sheldon's paper to Stephen Hawking, Howard asks Sheldon to compliment him once for his work. Sheldon replies that he has never said that Howard is bad at his job, only that his job is inconsequential. Howard looks past this and tells him that he gave Stephen Hawking his paper three days ago and that he wants to meet him. At his meeting, Professor Hawking tells Sheldon that the paper is excellent, though he mentions that Sheldon made a small arithmetic mistake on page two. Once Sheldon finds it and realizes he gave his idol a flawed paper, he faints in front of Hawking. Professor Hawking remarks, "Oh great, another fainter". Guest star: Stephen Hawking as himself Recurring character: Carol Ann Susi as Mrs. Wolowitz Absent: Mayim Bialik as Amy Title reference: Sheldon's excitement over the possibility of meeting Stephen Hawking.
109	22	"The Stag Convergence"	Peter Chakos	Story: Billy Prady, Steve Holland & Eric Kaplan Teleplay: Chuck Lorre, Steven Molaro & Jim Reynolds	April 26, 2012 (2012-04-26)	3X6872	12.65
The guys discuss Howard's bachelor party. Howard declines strippers as he promised Bernadette there wouldn't be any. At the party, everyone offers a toast. Sheldon tells jokes that fall flat but wishes Howard well. Leonard tells everyone he has had sex in the ocean and does crazy things. Stuart tells everyone how unhappy he is living in the back of his comic book store while Barry Kripke complains that there are no "stwippuhs" (strippers). Raj finishes with stories about Howard losing his virginity to his second-cousin, having sex with a Sailor Moon girl at ComicCon and Leonard and Raj getting him a Jewish role-playing prostitute in Las Vegas. All the while, Wil Wheaton is recording everything and uploads it to the internet. When Bernadette picks Howard and Raj up, she is mad at both of them after seeing the video. She wonders how she can marry a man that she doesn't seem to know. When talking with Penny and Amy, she becomes upset at Penny since she knew about his past when she set them up sending her out of the room in tears. Howard shows up and gives Penny a message that he is sorry, and Howard that Bernadette knows now is who he is because of her, which reduces Penny to tears. Bernadette hears him and tells him that the wedding is still on, though that she is still mad at him. They all end in a group hug which Amy finds exciting. Leonard whom Penny earlier had told that he doesn't do crazy things, shows up in the laundry and proclaims that they are going to have sex right then on the washing machine. Penny scoffs, and refuses, and says that he should help her with the laundry. Leonard replies, "Folding sheets in my underwear: still pretty crazy!" Recurring characters: Kevin Sussman as Stuart Bloom, John Ross Bowie as Barry Kripke, and Wil Wheaton as himself Note: Raj talks about the time they went camping and Howard revealed that he lost his virginity to his cousin. This is a reference to episode 3x08, "The Adhesive Duck Deficiency." Howard even directly quotes himself by insisting "She was my second cousin." Title reference: The guys coming together for Howard's bachelor party.
110	23	"The Launch Acceleration"	Mark Cendrowski	Story: Chuck Lorre, Steven Molaro & Jim Reynolds Teleplay: Bill Prady, Steve Holland & Maria Ferrari	May 3, 2012 (2012-05-03)	3X6873	13.91
Howard receives word from NASA that his mission to the International Space Station has been cancelled, due to the Soyuz rocket failing its pressure test. Despite the sympathy shown to him from the guys and Bernadette, Howard is secretly relieved, as he was starting to get scared of going into space anyway. However, NASA later calls and informs him that his launch has been rescheduled, and the launch date is the Friday before their wedding. Bernadette is relieved for Howard, but he uses every excuse he can think of not to go including going to see his prospective father-in-law. Bernadette’s father tells Howard that he did not think that he was the right man for his little girl until he heard about him going into space. Also he mentioned not to worry about the wedding deposit and that Bernadette can always find someone else if he doesn't come back. Meanwhile, Penny offers to take her "beta test" relationship with Leonard to the next level and takes him to bed, but it ends badly when Leonard proposes to Penny in the middle of sex. Later Penny sees Leonard in the hallway, kisses him and then gives him "No" to the marriage proposal, though informing him that they are still dating. Elsewhere, Amy uses her neurobiological skills to increase Sheldon's feelings for her by making him happy. She starts off by inviting him to dinner, during which she plays Super Mario Bros. theme background music (reminding him of "the best 600 hours of [his] childhood") while serving him spaghetti with little hot dogs (which his mother used to make) and Strawberry Quik (his favorite pink fluid, narrowly beating out Pepto Bismol). Later, she plays doctor "Star Trek style" (Amy dressed in Star Trek attire). Amy’s actions seem to work on Sheldon, who isn’t happy about it but makes no attempt to stop her. Guest stars: Casey Sander as Mr. Rostenkowski, Karl T. Wright as Jimmy, and Robert Clotworthy as Dave Roeger (voice) Title Reference: Howard's NASA launch being bumped up two days before his wedding.
111	24	"The Countdown Reflection"	Mark Cendrowski	Story: Bill Prady, Eric Kaplan & Steve Holland Teleplay: Chuck Lorre, Steven Molaro & Jim Reynolds	May 10, 2012 (2012-05-10)	3X6874	13.72
Howard Wolowitz and his two fellow astronauts, Dimitri Rezinov and Mike Massimino are in the Soyuz capsule, awaiting lift-off to the International Space Station. Nervous, and not looking forward to the launch, Howard begins to reflect on the last couple of days, revealing that he married Bernadette before he left. After giving Bernadette a necklace with a star on it which he plans to take into space with him, she tells him that she wants them married before he takes off, and they decide to go to the city hall that afternoon to marry there, and have the reception when he gets back. Amy is devastated that her position as Maid of Honor has been reduced to nothing, but is allowed to wear the dress she bought to city hall. No wedding occurs because there are too many couples in front of them. Raj suggests they get married on the roof of Leonard, Sheldon and Penny's apartment building on Sunday morning, which will coincide with a satellite taking new photographs of their city of Pasadena, California. The five friends then get ordained as ministers over the internet in order to perform the marriage properly. Although the wedding ceremony is heavily improvised, and is constantly interrupted by Mrs. Wolowitz, as well as Leonard's needling Penny over her rejection of his marriage proposal, it is a success. As Howard and Bernadette kiss, an overhead shot of the wedding party is seen as the view pulls back until the entire earth is seen from space. The episode ends with Howard being launched into orbit. Watching nervously, Bernadette takes Raj’s hand, Penny takes Leonard’s hand and a very surprised Amy has her hand taken by Sheldon who wishes Howard well with the words "Boldly go, Howard Wolowitz" and Howard yelling Oy vey. Guest stars: Mike Massimino as himself and Casey Sander as Mr. Rostenkowski Recurring characters: Carol Ann Susi as Mrs. Wolowitz and Pasha Lychnikoff as Dimitri Rezinov Title reference: Howard's flashback of the events leading up to his wedding with Bernadette as he is about to launch into space.

Ratings

U.S. Nielsen ratings

Episode No.	Title	Air date	18–49	Viewers (millions)
1	"The Skank Reflex Analysis"	02011-09-22September 22, 2011	4.9/15	14.30
2	"The Infestation Hypothesis"	02011-09-22September 22, 2011	5.1/14	14.94
3	"The Pulled Groin Extrapolation"	02011-09-29September 29, 2011	4.9/15	14.74
4	"The Wiggly Finger Catalyst"	02011-10-06October 6, 2011	4.5/14	13.92
5	"The Russian Rocket Reaction"	02011-10-13October 13, 2011	4.6/14	13.58
6	"The Rhinitis Revelation"	02011-10-20October 20, 2011	5.1/16	14.93
7	"The Good Guy Fluctuation"	02011-10-27October 27, 2011	4.6/13	14.54
8	"The Isolation Permutation"	02011-11-03November 3, 2011	5.4/16	15.98
9	"The Ornithophobia Diffusion"	02011-11-10November 10, 2011	5.3/15	15.89
10	"The Flaming Spittoon Acquisition"	02011-11-17November 17, 2011	5.3/15	15.05
11	"The Speckerman Recurrence"	02011-12-08December 8, 2011	4.6/14	14.02
12	"The Shiny Trinket Maneuver"	02012-01-12January 12, 2012	5.3/15	16.13
13	"The Recombination Hypothesis"	02012-01-19January 19, 2012	5.3/15	15.83
14	"The Beta Test Initiation"	02012-01-26January 26, 2012	5.5/16	16.13
15	"The Friendship Contraction"	02012-02-02February 2, 2012	5.5/16	16.54
16	"The Vacation Solution"	02012-02-09February 9, 2012	5.6/16	16.21
17	"The Rothman Disintegration"	02012-02-16February 16, 2012	5.1/15	15.65
18	"The Werewolf Transformation"	02012-02-23February 23, 2012	5.3/16	16.20
19	"The Weekend Vortex"	02012-03-08March 8, 2012	5.1/15	15.04
20	"The Transporter Malfunction"	02012-03-29March 29, 2012	4.7/15	13.96
21	"The Hawking Excitation"	02012-04-05April 5, 2012	4.4/15	13.29
22	"The Stag Convergence"	02012-04-26April 26, 2012	4.1/13	12.65
23	"The Launch Acceleration"	02012-05-03May 3, 2012	4.7/16	13.91
24	"The Countdown Reflection"	02012-05-10May 10, 2012	4.4/15	13.72

Canadian ratings

Episode No.	Title	Air date	Viewers (millions)	Weekly Rank
1	"The Skank Reflex Analysis"	02011-09-22September 22, 2011	3.718	3
2	"The Infestation Hypothesis"	02011-09-22September 22, 2011	4.053	2
3	"The Pulled Groin Extrapolation"	02011-09-29September 29, 2011	3.693	1
4	"The Wiggly Finger Catalyst"	02011-10-06October 6, 2011	3.283	1
5	"The Russian Rocket Reaction"	02011-10-13October 13, 2011	3.678	1
6	"The Rhinitis Revelation"	02011-10-20October 20, 2011	3.550	1
7	"The Good Guy Fluctuation"	02011-10-27October 27, 2011	3.751	1
8	"The Isolation Permutation"	02011-11-03November 3, 2011	3.762	1
9	"The Ornithophobia Diffusion"	02011-11-10November 10, 2011	3.483	1
10	"The Flaming Spittoon Acquisition"	02011-11-17November 17, 2011	3.868	1
11	"The Speckerman Recurrence"	02011-12-08December 8, 2011	3.552	1
12	"The Shiny Trinket Maneuver"	02012-01-12January 12, 2012	3.566	1
13	"The Recombination Hypothesis"	02012-01-19January 19, 2012	3.534	1
14	"The Beta Test Initiation"	02012-01-26January 26, 2012	3.348	1
15	"The Friendship Contraction"	02012-02-02February 2, 2012	3.754	4
16	"The Vacation Solution"	02012-02-09February 9, 2012	3.216	2
17	"The Rothman Disintegration"	02012-02-16February 16, 2012	3.537	1
18	"The Werewolf Transformation"	02012-02-23February 23, 2012	3.513	2
19	"The Weekend Vortex"	02012-03-08March 8, 2012	3.648	1
20	"The Transporter Malfunction"	02012-03-29March 29, 2012	3.388	1
21	"The Hawking Excitation"	02012-04-05April 5, 2012	3.181	1
22	"The Stag Convergence"	02012-04-26April 26, 2012	3.170	1
23	"The Launch Acceleration"	02012-05-03May 3, 2012	3.232	1
24	"The Countdown Reflection"	02012-05-10May 10, 2012	4.035	1

Australian ratings

This season began airing on the Nine Network on October 10, 2011 at 7:30 pm.

Episode No.	Title	Air date	Timeslot	Viewers (millions)	Nightly rank	Weekly rank
1	"The Skank Reflex Analysis"	02011-10-10October 10, 2011	Monday 7:30 pm–8:00 pm	1.505	2	11
2	"The Infestation Hypothesis"	02011-10-10October 10, 2011	Monday 8:00 pm–8:30 pm	1.606	1	5
3	"The Pulled Groin Extrapolation"	02011-10-17October 17, 2011	Monday 7:30 pm–8:00 pm	1.488	2	4
4	"The Wiggly Finger Catalyst"	02011-10-17October 17, 2011	Monday 8:00 pm–8:30 pm	1.551	1	3
5	"The Russian Rocket Reaction"	02011-10-24October 24, 2011	Monday 8:00 pm–8:30 pm	1.369	2	5
6	"The Rhinitis Revelation"	02011-10-31October 31, 2011	Monday 8:00 pm–8:30 pm	1.397	1	6
7	"The Good Guy Fluctuation"	02011-11-07November 7, 2011	Monday 8:00 pm–8:30 pm	1.346	2	6
8	"The Isolation Permutation"	02011-11-14November 14, 2011	Monday 8:00 pm–8:30 pm	1.359	2	N/A
9	"The Ornithophobia Diffusion"	02011-11-21November 21, 2011	Monday 8:30 pm–9:00 pm	1.369	3	N/A
10	"The Flaming Spittoon Acquisition"	02012-01-23January 23, 2012	Monday 7:30 pm–8:00 pm	1.641	1	N/A
11	"The Speckerman Recurrence"	02012-01-30January 30, 2012	Monday 8:00 pm–8:30 pm	1.349	2	N/A
12	"The Shiny Trinket Maneuver"	02012-02-13February 13, 2012	Monday 7:30 pm–8:00 pm	1.347	5	N/A
13	"The Recombination Hypothesis"	02012-02-13February 13, 2012	Monday 8:00 pm–8:30 pm	1.491	3	N/A
14	"The Beta Test Initiation"	02012-02-14February 14, 2012	Tuesday 7:30 pm–8:00 pm	1.126	5	N/A
15	"The Friendship Contraction"	02012-02-20February 20, 2012	Monday 8:00 pm–8:30 pm	1.374	3	N/A
16	"The Vacation Solution"	02012-02-27February 27, 2012	Monday 8:00 pm–8:30 pm	1.344	3	N/A
17	"The Rothman Disintegration"	02012-03-05March 5, 2012	Monday 8:00 pm–8:30 pm	1.301	3	N/A
18	"The Werewolf Transformation"	02012-03-12March 12, 2012	Monday 8:00 pm–8:30 pm	1.312	3	N/A
19	"The Weekend Vortex"	02012-03-19March 19, 2012	Monday 8:00 pm–8:30 pm	1.311	3	N/A
20	"The Transporter Malfunction"	02012-04-17April 17, 2012	Tuesday 9:00 pm–9:30 pm	1.506	2	N/A
21	"The Hawking Excitation"	02012-04-24April 24, 2012	Tuesday 9:00 pm–9:30 pm	1.867	2	N/A

Notes

• ^a Due to an error in Australian ratings data, "The Skank Reflex Analysis" and "The Infestation Hypothesis" were averaged with repeat episodes that aired the following night for the weekly rankings. As a result, both episodes' ratings significantly decreased to 1.225 million and 1.321 million viewers respectively. Based on the original unadjusted figures, the episodes would have ranked first ("The Infestation Hypothesis") and third ("The Skank Reflex Analysis") for the week. These were unadjusted preliminary figures.

UK ratings

The season aired Thursday nights at 8pm on E4. All viewing figures and ranks are sourced from BARB.

Episode No.	Title	Air date	E4 Viewers	E4 Rank	E4 +1 Viewers	E4 +1 Rank	Total Viewers (millions)	Rank (cable)
1	"The Skank Reflex Analysis"	02011-11-03November 3, 2011	1.081	5	0.258	9	1.339	13
2	"The Infestation Hypothesis"	02011-11-10November 10, 2011	1.115	2	0.297	5	1.312	7
3	"The Pulled Groin Extrapolation"	02011-11-10November 10, 2011	0.962	3	0.298	4	1.260	9
4	"The Wiggly Finger Catalyst"	02011-11-17November 17, 2011	1.025	2	0.316	1	1.341	9
5	"The Russian Rocket Reaction"	02011-11-24November 24, 2011	1.215	1	0.364	2	1.579	5
6	"The Rhinitis Revelation"	02011-12-01December 1, 2011	1.133	2	0.286	4	1.419	8
7	"The Good Guy Fluctuation"	02011-12-08December 8, 2011	1.079	2	0.316	3	1.395	7
8	"The Isolation Permutation"	02011-12-15December 15, 2011	1.176	2	0.330	3	1.506	7
9	"The Ornithophobia Diffusion"	02011-12-22December 22, 2011	1.152	1	0.390	1	1.542	8
10	"The Flaming Spittoon Acquisition"	02011-12-29December 29, 2011	Unavailable
11	"The Speckerman Recurrence"	02012-01-05January 5, 2012	1.250	1	0.420	1	1.670	6
12	"The Shiny Trinket Maneuver"	02012-03-29March 29, 2012	0.990	1	0.309	2	1.299	10
13	"The Recombination Hypothesis"	02012-04-05April 5, 2012	1.713	1	0.394	2	2.107	2
14	"The Beta Test Initiation"	02012-04-05April 5, 2012	1.669	2	0.415	1	2.084	3
15	"The Friendship Contraction"	02012-04-12April 12, 2012	1.559	1	0.442	1	2.001	2
16	"The Vacation Solution"	02012-04-19April 19, 2012	1.935	1	0.345	5	2.280	2
17	"The Rothman Disintegration"	02012-04-19April 19, 2012	1.637	2	0.378	2	2.015	3

References

General references

• "The Big Bang Theory Season 5 episodes". TV Guide. Retrieved October 1, 2011. 
• "Shows A-Z – big bang theory, the on CBS". the Futon Critic. Retrieved October 1, 2011. 
• "The Big Bang Theory: Episode Guide". MSN TV. Retrieved October 1, 2011. 
• "The Big Bang Theory Episode Recaps". CBS. Retrieved October 1, 2011.