The Big Bang Theory Episodes


A woman who moves into an apartment next door to two brilliant but socially awkward physicists shows them how little they know about life outside of the laboratory.

The Big Bang Theory Season 5

Episode 2: The Infestation Hypothesis
Date Aired: Sep 22, 2011

Description: Penny and Sheldon clash, and Amy is caught in the middle of their battle; and Leonard tries to spice up his long-distance relationship with Priya.
Episode 1: The Skank Reflex Analysis
Date Aired: Sep 22, 2011

Description: In the fifth-season opener, Penny hits a low point when she realizes what she's done by sleeping with Raj; and Sheldon becomes the leader of the paintball team

The Big Bang Theory Season 4

Episode 24: The Roomate Transmogrification
Date Aired: May 19, 2011

Description: 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. Meanwhile, Koothrappali becomes Sheldon's new roommate after hearing Leonard and Priya engaging in a "Star Trek" bedroom fantasy.
Episode 23: The Engagement Reaction
Date Aired: May 12, 2011

Description: When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.
Episode 22: The Wildebeest Implementation
Date Aired: May 05, 2011

Description: Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.
Episode 21: The Agreement Dissection
Date Aired: Apr 28, 2011

Description: When Priya finds a loophole in the roommate agreement to throw Sheldon out for the night, Penny, Amy, and Bernadette take Sheldon to a nightclub.
Episode 20: The Herb Garden Germination
Date Aired: Apr 07, 2011

Description: Sheldon and Amy experiment on their friends by spreading gossip, while Howard takes a big step in his relationship with Bernadette.
Episode 19: The Zarnecki Incursion
Date Aired: Mar 31, 2011

Description: The gang goes all out to help Sheldon find the person responsible for hacking his online gaming account.
Episode 18: The Prestidigitation Approximation
Date Aired: Mar 10, 2011

Description: Leonard must choose between being with his girlfriend Priya or having his friendship with Penny. Meanwhile, Howard drives Sheldon crazy with a magic trick.
Episode 17: The Toast Derivation
Date Aired: Feb 24, 2011

Description: Sheldon becomes concerned when everybody begins to hang out at Raj's apartment and discovers Leonard is the center of the group.
Episode 16: The Cohabitation Formulation
Date Aired: Feb 17, 2011

Description: As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.
Episode 15: The Benefactor Factor
Date Aired: Feb 10, 2011

Description: The guys are asked to attend a fundraising event to earn funding for their research. Sheldon convinces Leonard to get "friendly" with a wealthy benefactor to secure a donation.
Episode 14: The Thespian Catalyst
Date Aired: Feb 03, 2011

Description: To improve his skills as an instructor, Sheldon asks Penny to give him acting lessons.
Episode 13: The Love Car Displacement
Date Aired: Jan 20, 2011

Description: Tension runs high as the entire gang spends the weekend together at a science convention.
Episode 12: The Bus Pants Utilization
Date Aired: Jan 06, 2011

Description: Leonard's idea for a smartphone app derails his friendship with Sheldon.
Episode 11: The Justice League Recombination
Date Aired: Dec 16, 2010

Description: The guys enter a costume contest as members of the Justice League and convince Penny's new boyfriend to join them.
Episode 10: The Alien Parasite Hypothesis
Date Aired: Dec 09, 2010

Description: Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.
Episode 9: The Boyfriend Complexity
Date Aired: Nov 18, 2010

Description: Leonard has been asked by Penny to pose as her boyfriend when her father visits. Howard, Raj, and Bernadette are up all night looking through a telescope.
Episode 8: The 21-Second Excitation
Date Aired: Nov 11, 2010

Description: The guys camp out all night waiting to see a new movie while Penny and Bernadette invite Amy to her first slumber party.
Episode 7: The Apology Insufficiency
Date Aired: Nov 04, 2010

Description: Everyone is investigated by an FBI agent when Howard needs to obtain a security clearance. Sheldon is baffled when Howard refuses to accept his apology.
Episode 6: The Irish Pub Formulation
Date Aired: Oct 28, 2010

Description: Leonard keeps an affair secret from Sheldon, Howard and Raj.
Episode 5: The Desperation Emanation
Date Aired: Oct 21, 2010

Description: Sheldon has doubts about continuing to date Amy after meeting her mother. Leonard laments the fact everybody except him is in a relationship. Source:
Episode 4: The Hot Troll Deviation
Date Aired: Oct 14, 2010

Description: Howard must face the music when some embarrassing information about him is revealed. Sheldon and Raj have work issues. Source:
Episode 3: The Zazzy Substitution
Date Aired: Oct 07, 2010

Description: Following his breakup with Amy, the gang becomes concerned with Sheldon's obsessive search for non-human companionship, and they call his mother to intervene. Source:
Episode 2: The Cruciferous Vegetable Amplification
Date Aired: Sep 30, 2010

Description: When Sheldon calculates the technology to download his consciousness into a robot won't be invented soon enough, he desperately tries to find a way to increase his lifespan. Source:
Episode 1: The Robotic Manipulation
Date Aired: Sep 23, 2010

Description: Penny ends up tagging along on Sheldon's first-ever date with Amy Fowler.

The Big Bang Theory Season 3

Episode 23: The Lunar Excitation
Date Aired: May 24, 2010

Description: Penny has a night of angry, drunken sex with Leonard, which Leonard soon misinterprets as something other than a mistake. Meanwhile, Wolowitz and Koothrappali search for Sheldon's perfect match online. Source:
Episode 22: The Staircase Implementation
Date Aired: May 18, 2010

Description: After Leonard and Sheldon get in a fight over the thermostat, Leonard goes to Penny's apartment and tells her about how he met Sheldon for the first time and how they became roommates...and what happened to the elevator. Source:
Episode 21: The Plimpton Stimulation
Date Aired: May 10, 2010

Description: Sheldon and Penny are both disturbed and disappointed when Leonard hooks up with Sheldon's visiting female physicist friend.
Episode 20: The Spaghetti Catalyst
Date Aired: May 03, 2010

Description: With Leonard and Penny now broken up, Sheldon is forced to go behind Leonard's back to spend time with her.
Episode 19: The Wheaton Recurrence
Date Aired: Apr 11, 2010

Description: Leonard and Penny's relationship is on the line when they start fighting.
Episode 18: The Pants Alternative
Date Aired: Mar 21, 2010

Description: Sheldon needs the gang's help in overcoming his fear of public speaking when he receives an award.
Episode 17: The Precious Fragmentation
Date Aired: Mar 07, 2010

Description: When the guys find an actual ring from the "Lord of the Rings" trilogy at a garage sale, their friendship is threatened.
Episode 16: The Excelsior Acquisition
Date Aired: Feb 28, 2010

Description: Sheldon misses an opportunity to get Stan Lee's autograph because he has to make an appearance in traffic court.
Episode 15: The Large Hadron Collision
Date Aired: Feb 07, 2010

Description: When Leonard must travel to Switzerland on Valentine's Day to visit the CERN laboratory, Sheldon uses any and all means to be his guest instead of Penny.
Episode 14: The Einstein Approximation
Date Aired: Jan 31, 2010

Description: Sheldon acts even more strangely when he is stumped by a difficult physics question, so he is forced to resort to Einstein-inspired measures to unclutter his mind and solve the problem.
Episode 13: The Bozeman Reaction
Date Aired: Jan 17, 2010

Description: When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.
Episode 12: The Psychic Vortex
Date Aired: Jan 10, 2010

Description: With Leonard and Howard going on a double date, Raj talks a reluctant Sheldon into attending a mixer at the university. Surprisingly, Raj and Sheldon end up meeting and having a good time with two beautiful, fun loving women named Abby and Martha. Raj and Sheldon have vastly differing opinions on what they want to get out of a second date that Abby and Martha want with them. Meanwhile, Leonard reconsiders his relationship with Penny when he learns that she believes in psychics. Penny reconsiders her relationship with Leonard after he mocks her belief in psychics. One of the two is going to have to compromise their steadfast belief if their relationship is to continue. Source:
Episode 11: The Maternal Congruence
Date Aired: Dec 13, 2009

Description: Leonard's mother makes a visit to his dismay and Sheldon's delight.
Episode 10: The Gorilla Experiment
Date Aired: Dec 06, 2009

Description: Sheldon attempts to help Penny understand physics to impress Leonard, and Wolowitz becomes jealous when his new girlfriend takes an interest in Leonard's research.
Episode 9: The Vengeance Formulation
Date Aired: Nov 22, 2009

Description: Sheldon vows payback after Kripke humiliates him on the radio. Howard gets advice concerning his relationship with Bernadette...from "Battlestar Galactica's" Katee Sackhoff.
Episode 8: The Adhesive Duck Deficiency
Date Aired: Nov 15, 2009

Description: Penny separates her shoulder in the bathtub, and is forced to turn to Sheldon for help. Meanwhile, the rest of the guys accidentally get stoned in the desert while waiting for a meteor shower. Source:
Episode 7: The Guitarist Amplification
Date Aired: Nov 08, 2009

Description: Sheldon is forced to play peacemaker when Leonard and Penny have an argument, mainly because their fighting is bringing back repressed childhood memories. Source:
Episode 6: The Cornhusker Vortex
Date Aired: Nov 01, 2009

Description: To blend in better with several of Penny's friends from back home, Leonard learns about football...from Sheldon. Meanwhile, a loss in a kite war threatens to end Raj and Howard's friendship. Source:
Episode 5: The Creepy Candy Coating Corollary
Date Aired: Oct 19, 2009

Description: Wolowitz begs Penny to set him up with one of her friends; Sheldon seeks payback against Wil Wheaton. Source:
Episode 4: The Pirate Solution
Date Aired: Oct 12, 2009

Description: Raj must find a new job or be sent back to India, but Sheldon has a solution, which leaves Leonard and Penny dealing with Howard as third wheel. Source:
Episode 3: The Gothowitz Deviation
Date Aired: Oct 05, 2009

Description: Sheldon attempts to covertly alter Penny's habits, while Howard and Raj try their luck meeting women at a Goth-style club. Source:
Episode 2: The Jiminy Conjecture
Date Aired: Sep 28, 2009

Description: Leonard and Penny's first night together goes awkwardly. Sheldon and Howard wager on the species of a cricket. Source:
Episode 1: The Electric Can Opener Fluctuation
Date Aired: Sep 21, 2009

Description: After returning from the North Pole, a conflict among the guys sends Sheldon back to Texas and interferes with Leonard's reunion with Penny. Source:
Currently On Recess: 19