The Big Bang Theory

Season 5

TV-PG

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In season five, Penny and Leonard's relationship is relaunched in full "beta test" mode, while Sheldon, Howard, and Raj discover the feminine mystique is something that cannot be easily graphed or calculated. As Sheldon makes begrudging amendments to his "Relationship Agreement" with his "friend-who-happens-to-be-a-girl" Amy Farrah Fowler, Raj contemplates an arranged marriage, and Howard is all-systems-go for both is NASA space launch and wedding to the spirited Bernadette.

Where to Watch The Big Bang Theory • Season 5

24 Episodes

The Skank Reflex Analysis
E1
The Skank Reflex AnalysisPenny is worried with how damaged her friendship with the guys will be in the aftermath of her sleeping with Raj while Sheldon becomes the leader of the paintball team.
The Infestation Hypothesis
E2
The Infestation HypothesisA fight between Sheldon and Penny leaves Amy caught in the middle, while Leonard tries to spice up his long-distance relationship with Priya.
The Pulled Groin Extrapolation
E3
The Pulled Groin ExtrapolationLeonard and Amy get to know each other better, while Howard and Bernadette spend the weekend with Mrs. Wolowitz.
The Wiggly Finger Catalyst
E4
The Wiggly Finger CatalystPenny plays Matchmaker for Raj, which results in him finding a girl he is comfortable talking to.
The Russian Rocket Reaction
E5
The Russian Rocket ReactionSheldon and Leonard get invited to a party at Wil Wheaton's house, and Howard gets an out-of-this-world opportunity.
The Rhinitis Revelation
E6
The Rhinitis RevelationSheldon's mother, Mary Cooper, comes to visit, but Sheldon is annoyed that she also spends time with the rest of the gang, instead of catering to his every demand.
The Good Guy Fluctuation
E7
The Good Guy FluctuationA cute comic book artist puts Leonard and Priya’s relationship to the test, while Sheldon tries to scare the guys for Halloween.
The Isolation Permutation
E8
The Isolation PermutationAmy becomes heartbroken when she discovers that Penny and Bernadette went wedding dress shopping without her.
The Ornithophobia Diffusion
E9
The Ornithophobia DiffusionLeonard and Penny try hanging out as friends on a 'non-date', but end up purposely ruining each others chances with perspective dates. Meanwhile, Sheldon enlists the help of Bernadette and Amy to overcome his fear of birds.
The Flaming Spittoon Acquisition
E10
The Flaming Spittoon AcquisitionWhen Stuart asks Amy out on a date, Sheldon must confront his feelings and consider where his relationship with Amy is going.
The Speckerman Recurrence
E11
The Speckerman RecurrenceLeonard must face his fears after being contacted by his high school tormentor.
The Shiny Trinket Maneuver
E12
The Shiny Trinket ManeuverSheldon gets in trouble with Amy when he isn't impressed by her recent accomplishment, and Howard must come to grips with Bernadette's dislike of children.
The Recombination Hypothesis
E13
The Recombination HypothesisLeonard, who broke up with Priya, asks Penny out to a spur-of the-moment romantic dinner for two, and the duo contemplates on their relationship.
The Beta Test Initiation
E14
The Beta Test InitiationLeonard and Penny deal with the idea of starting a relationship again and Raj finally finds a "woman" he can talk to without being drunk, in the form of Siri on his new phone. Meanwhile, Sheldon decides to start a YouTube series entitled "Sheldon Cooper presents Fun with Flags" with the help of Amy.
The Friendship Contraction
E15
The Friendship ContractionSheldon's selfish demands force Leonard to reconsider their friendship. Meanwhile, Wolowitz tries to pick his astronaut nickname.
The Vacation Solution
E16
The Vacation SolutionWhen Sheldon is forced to take his vacation, he goes to work with Amy in her neurobiology lab.
The Rothman Disintegration
E17
The Rothman DisintegrationSheldon battles Kripke for a coveted office at the university. Penny receives a very unusual gift from Amy.
The Werewolf Transformation
E18
The Werewolf TransformationSheldon becomes agitated when his regular barber is out sick. Astronaut training causes Howard to reconsider wanting to go into space. Penny beats Leonard in chess, the first time she plays.
The Weekend Vortex
E19
The Weekend VortexSheldon must choose between joining Amy at her aunt's birthday party or playing videogames all weekend with the guys.
The Transporter Malfunction
E20
The Transporter MalfunctionPenny buys Leonard and Sheldon “Star Trek” collectibles as a thank-you, leading Sheldon to be haunted by Mr. Spock. Meanwhile, Raj decides he has met the “Future Mrs. Koothrappali” after his parents set him up on a date.
The Hawking Excitation
E21
The Hawking ExcitationWhen Wolowitz gets to work with Stephen Hawking, Sheldon is willing to do anything to meet his hero.
The Stag Convergence
E22
The Stag ConvergenceAfter the guys throw Howard a bachelor party, Bernadette reconsiders marrying him after learning about his sexual history.
The Launch Acceleration
E23
The Launch AccelerationWhen NASA moves up Howard's mission, he must face his fears and Bernadette's dad, thus putting the wedding plans in jeopardy. Meanwhile, Leonard says something surprising to Penny in the bedroom.
The Countdown Reflection
E24
The Countdown ReflectionThe fifth season ends with Howard and Bernadette deciding to get married before his NASA mission, causing the gang to scurry into overdrive in an effort to stage the wedding. NASA astronaut Mike Massimino has a cameo as himself.