The Big Bang Theory
Monday 8:30 PM on CBS
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Season 5
- Ep 17The Rothman Disintegration2/16/12
When a new office space is made available, Sheldon goes head to head with his nemesis, Kripke. Also, Penny is unsettled by a gift from Amy. - Ep 16The Vacation Solution2/9/12
Forced to use his vacation time, Sheldon dabbles in biology in Amy's lab. Bernadette reveals to the girls that her father wants her to make Howard sign a pre-nup.
- Ep 15The Friendship Contraction2/2/12
Leonard can't take Sheldon's continued selfishness and agrees to dissolve the Roommate Agreement. Howard wants to have a cool nickname for when he's an astronaut.
- Ep 14The Beta Test Initiation1/26/12
Leonard and Penny create lists of 'bugs' in their relationship in an attempt to strengthen it. Meanwhile, Sheldon and Amy create a YouTube video series called Fun with Flags, and Raj develops an unhealthy attachment to Siri on his iPhone.
- Ep 13The Recombination Hypothesis1/19/12
Leonard asks Penny out on an impromptu romantic date.
- Ep 12The Shiny Trinket Maneuver1/12/12
Sheldon finds himself in hot water when he doesn't appreciate Amy's recent accomplishment. Howard discovers Bernadette doesn't interact well with children.
- Ep 11The Speckerman Recurrance12/8/11
Leonard is hesitant when a bully from high school wants to meet for a drink. Meanwhile, Penny comes to realize she was a bully herself.
- Ep 10The Flaming Spittoon Acquisition11/17/11
Sheldon finds himself jealous when Amy goes on a date with Stuart. The other guys can't resist the allure of the latest collectable card game expansion pack.
- Ep 9The Ornithophobia Diffusion11/10/11
Sheldon tries to cure his phobia of birds, while Leonard and Penny go to a movie just as friends. - Ep 8The Isolation Permutation11/3/11
When it is revealed that Penny and Bernadette went wedding dress shopping without her, Amy becomes heartbroken and pressures Sheldon for sex.
- Ep 7The Good Guy Fluctuation10/27/11
Leonard finds himself drawn towards a comely comic book illustrator. Meanwhile, Sheldon tries to scare the gang for Halloween.
- Ep 6The Rhinitis Revelation10/20/11
When his mother comes for another visit, Sheldon is disappointed that she's stopped being the mother he wants her to be.
- Ep 5The Russian Rocket Reaction10/13/11
Sheldon is miffed that Leonard plans to attend a party hosted by his nemesis, Wil Wheaton. Meanwhile, Howard is offered a chance to be a payload specialist on the International Space Station.
- Ep 4The Wiggly Finger Catalyst10/6/11
Penny finds the perfect girl for Raj to date. Meanwhile, Sheldon uses Dungeons & Dragons dice to make life's trivial decisions.
- Ep 3The Pulled Groin Extrapolation9/29/11
Leonard escorts Amy to a wedding. Meanwhile, Howard convinces Bernadette to spend the weekend with him at his mother's house as a trial run, and Sheldon gets involved in model trains. - Ep 2The Infestation Hypothesis9/22/11
Sheldon is aghast to learn the new chair in Penny's apartment was someone else's garbage. Leonard and Priya try a long-distance relationship.
- Ep 1The Skank Reflex Analysis9/22/11
After spending the night with Raj, Penny is worried that her friendship with the guys is in jeopardy, while Sheldon becomes the paintball team leader.
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Season 4
- Ep 24The Roommate Transmogrification5/19/11
Hearing Star Trek sex games between Leonard and Priya sends Raj to live with Sheldon. Bernadette's earning her Ph.D makes the guys mock Wolowitz for not having one even more. - Ep 23The Engagement Reaction5/12/11
Mrs. Wolowitz ends up in the hospital after Howard tells her he's marrying Bernadette. While there, Leonard stresses over Penny and Priya warming up to one another. - Ep 22The Wildebeest Implementation5/5/11
Amy recognizes a dinner invitation to be a chance for Bernadette to spy on Leonard and Priya for Penny. Meanwhile, a lonely Raj considers taking experimental medication to cure himself of his inability to talk to women while sober, and Sheldon devises three-person chess. - Ep 21The Agreement Dissection4/28/11
Miffed over Priya breaking down the Roommate Agreement using legal theory, Sheldon joins Penny, Bernadette, and Amy on their girls' night. - Ep 20The Herb Garden Germination4/7/11
Sheldon and Amy decide to start rumors about themselves as a social test. Meanwhile, Howard takes his relationship with Bernadette to an even higher level. - Ep 19The Zarnecki Incursion3/31/11
When Sheldon has his World of Warcraft account hacked and his character stolen from, the guys team up to discover out who did it. Meanwhile, Bernadette and Amy try to help Penny deal with Leonard's continuing relationship with Priya. - Ep 18The Prestidigitation Approximation3/10/11
Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Priya disapproves of Leonard continuing to be friends with Penny. - Ep 17The Toast Derivation2/24/11
Told Leonard is the center of the gang and miffed that they've started hanging out at Raj's, Sheldon seeks to form a new group of friends of which he can be the center. - Ep 16The Cohabitation Formulation2/17/11
Bernadette tells Howard that it's time to choose between moving in with her or staying with his mother. Leonard discovers Raj's sister Priya is back in town and reconnects with her, and Amy tries to comfort Penny when she finds out. - Ep 15The Benefactor Factor2/10/11
After meeting at a fundraising gala, an aged, but wealthy, Caltech donor makes Leonard ponder if he's willing to have sex with her to secure another donation. - Ep 14The Thespian Catalyst2/3/11
Hoping it will make him a better teacher, Sheldon has Penny give him acting lessons. Raj has fantasies about Bernadette. - Ep 13The Love Car Displacement1/20/11
A science convention at a hotel leads to Bernadette running into an ex-boyfriend and Wolowitz worrying he can't quite compare. - Ep 12The Bus Pants Utilization1/6/11
Their friendship becomes strained when Sheldon tries to take over Leonard's creation of a smartphone application that solves differential equations. - Ep 11The Justice League Recombination12/16/10
The guys get Zack and Penny to join their Justice League costume for a New Year's Eve bash at the comic book store. - Ep 10The Alien Parasite Hypothesis12/9/10
Amy crushes on one of Penny's dim ex-boyfriends, Zack. Raj and Wolowitz argue over who'd be the better superhero. - Ep 9The Boyfriend Complexity11/18/10
When Penny's father visits, she gets Leonard to pretend to still be her boyfriend. Meanwhile, Howard, Raj, and Bernadette spend the night on an astronomy project. - Ep 8The 21-Second Excitation11/11/10
The guys camp out in line to see a print of Raiders of the Lost Ark with 21 extra seconds and are outraged to see Wil Wheaton and his friends being allowed to skip the line. Penny and Bernadette invite Amy to their girls night. - Ep 7The Apology Insufficiency11/4/10
The rest of the gang is interviewed by the FBI for Wolowitz's security clearance, with Sheldon accidentally letting slip some damaging information. - Ep 6The Irish Pub Formulation10/28/10
When Raj's sister has a one-day layover he forbids the others from hooking up with her, unaware she and Leonard already did long ago. - Ep 5The Desperation Emanation10/21/10
Leonard is depressed to realize all the other guys have girlfriends, while he doesn't. Amy wants to introduce Sheldon to her mother. - Ep 4The Hot Troll Deviation10/14/10
Wolowitz tries to get back together with Bernadette. Sheldon and Raj go to war at the university. - Ep 3The Zazzy Substitution10/7/10
When Sheldon "breaks up" with Amy, the guys worry when he starts replacing her with cats. - Ep 2The Cruciferous Vegetable Amplification9/30/10
Sheldon calculates that he'll be dead before technology exists to download his consciousness into a robot, so he goes on a binge of healthy living and ultra-safety. - Ep 1The Robotic Manipulation9/23/10
Howard uses a robotic arm for his own pleasure. Penny assists Sheldon with his first date.
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Season 3
- Ep 23The Lunar Excitation5/24/10
Howard and Raj try to find the perfect match for Sheldon by setting him up on an Internet dating site. Seeing her moronic new boyfriend interact with the gang makes it abundantly clear to Penny that she can't go back to dating stereotypical dumb jocks after dating Leonard. - Ep 22The Staircase Implementation5/17/10
A squabble over the thermostat setting leads to Leonard going over to Penny's and recounting for her the story of how he met and moved in with Sheldon. - Ep 21The Plimpton Stimulation5/10/10
Sheldon hosts a visiting female physicist, but her intelligence seems matched by her libido. - Ep 20The Spaghetti Catalyst5/3/10
Subsequent to Leonard and Penny's break-up, Sheldon tries to hide from Leonard and the gang that he had a friendly spaghetti dinner at Penny's. - Ep 19The Wheaton Recurrence4/12/10
Sheldon gets to square off on the bowling alley against nemesis Wil Wheaton. Meanwhile, Leonard's miffed when Penny doesn't respond the way he hoped after saying, "I love you." - Ep 18The Pants Alternative3/22/10
Sheldon's fear of speaking in front of large groups threatens his ability to accept an award, so the gang tries to help him get ready for the big night. - Ep 17The Precious Fragmentation3/8/10
The discovery of a prop ring from The Lord of the Rings movies puts a strain on the guys' friendship. - Ep 16The Excelsior Acquisition3/1/10
An appearance in traffic court comes at the worst possible time for Sheldon—the same day Stan Lee is appearing at the comic book store. - Ep 15The Large Hadron Collision2/8/10
Leonard faces a dilemma in choosing between Sheldon or Penny to accompany him to Switzerland to see CERN's Large Hadron Collider on Valentine's Day. - Ep 14The Einstein Approximation2/1/10
Stuck on the solution to a physics problem, Sheldon seeks a number of alternative approaches to change his thinking and free the mental block—including working with Penny at The Cheesecake Factory. - Ep 13The Bozeman Reaction1/18/10
A robbery of their apartment sees Leonard and Sheldon call on their friends to devise a security system. - Ep 12The Psychic Vortex1/11/10
Leonard is aghast to find out a secret of Penny's: she believes in psychics. Meanwhile, Sheldon tries to assist Koothrappali in picking up a girl at a university party. - Ep 11The Maternal Congruence12/14/09
A Christmas visit from his mother has Leonard discovering she's kept a lot of news from him that she shares with Sheldon and worrying if she'll approve of his romance with Penny. - Ep 10The Gorilla Experiment12/7/09
Penny seeks Sheldon's help to better comprehend Leonard's physics work. Wolowitz sees green when Leonard invites Bernadette to watch an experiment. - Ep 9The Vengeance Formulation11/23/09
Barry Kripke pranks Sheldon during his spot on NPR, leaving him with a taste for vengeance. Wolowitz, pressured by Bernadette to define their relationship, gets advice from a fantasy version of Katee Sackhoff. - Ep 8The Adhesive Duck Deficiency11/16/09
With the rest of the gang off on a desert camping trip to view the Leonid meteor shower, Sheldon must play hero after Penny slips in the tub and dislocates her shoulder. - Ep 7The Guitarist Amplification11/9/09
Leonard and Penny's first big fight sees Sheldon playing mediator due to childhood trauma that's left him with an inability to be around loud verbal conflicts. - Ep 6The Cornhusker Vortex11/2/09
Leonard, hoping to fit in with Penny's football-loving friends, gets tutored in the sport by Sheldon. Raj is infuriated when Wolowitz's skirt-chasing leads to the loss of his prized patang. - Ep 5The Creepy Candy Coating Corollary10/19/09
Sheldon looks forward to squaring off against the the one actor from the Star Trek universe he holds enmity towards—Wil Wheaton—in a fantasy collectable card game tournament. Wolowitz cashes in on an old pact with Leonard to get Penny to set him up with a friend of hers. - Ep 4The Pirate Solution10/12/09
Facing a return to India, Raj needs a job desperately enough to consider working for Sheldon. Meanwhile, Howard becomes a third wheel to Leonard and Penny. - Ep 3The Gothowitz Deviation10/5/09
Howard takes Raj along to check out the Goth dating scene. Sheldon uses chocolate as part of a behavior modification experiment on Penny. - Ep 2The Jiminy Conjecture9/28/09
Sheldon and Howard wager comic books over a cricket's species. Meanwhile, a less-than-perfect romantic night agonizes Leonard and Penny. - Ep 1The Electric Can Opener Fluctuation9/21/09
Discovering that Leonard, Raj, and Howard fudged the results of his Arctic research expedition, a disgraced Sheldon heads home to Texas.
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Season 2
- Ep 23The Monopolar Expedition5/11/09
The guys' prestigious offer to work over the summer at the North Pole—and Penny's resultant behavior—leaves Leonard unsure if he should go. - Ep 22The Classified Materials Turbulence5/4/09
Leonard is torn between being honest or self-serving when Stuart asks his advice for an upcoming second date with Penny. Wolowitz realizes there's a crucial error in a toilet he designed for the International Space Station. - Ep 21The Vegas Renormalization4/27/09
Leonard and Raj take Wolowitz to Las Vegas to help him get over his break-up with Leslie. Sheldon, home alone and looking forward to it, locks himself out and has only one other place to stay—Penny's. - Ep 20The Hofstadter Isotope4/13/09
A fellow comic book enthusiast's hitting on Penny leads to Leonard, Raj, and Howard going to a bar's Ladies' Night. - Ep 19The Dead Hooker Juxtaposition3/30/09
Penny feels threatened when another sexy woman moves into the apartment building and angered when she senses the guys are being taken advantage of. - Ep 18The Work Song Nanocluster3/16/09
Penny's business selling hair accessories out of her apartment gets out of hand when an over-caffeinated Sheldon takes charge. - Ep 17The Terminator Decoupling3/9/09
The gang is thrilled when they see Terminator: The Sarah Connor Chronicles' Summer Glau is also aboard their train to San Francisco for a scientific symposium. Meanwhile, Sheldon frets over having forgotten a paper he wants to present to George Smoot. - Ep 16The Cushion Saturation3/2/09
Paintball leads to a squabble between Sheldon and Penny, as well as romance between Howard and Leslie. - Ep 15The Maternal Capacitance2/9/09
A visit from Leonard's mother ends up bringing him and Penny closer. - Ep 14The Financial Permeability2/2/09
When Sheldon loans money to Penny so she can pay her rent, it leads to Leonard coming face-to-face with her ex, Kurt. - Ep 13The Friendship Algorithm1/19/09
Looking to get friendly with Barry Kripke to gain access to a piece of high-tech lab equipment, Sheldon develops a flowchart process to make friends. - Ep 12The Killer Robot Instability1/12/09
Penny's criticism of Wolowitz's romantic life pushes him into depression and AWOL for a fighting robot battle the rest of guys are depending on him for. - Ep 11The Bath Item Gift Hypothesis12/15/08
Sheldon irks the gangs with his obession with proper Christmas gift protocol. Lenoard's crushed when Penny dates a colleague of his. - Ep 10The Vartabedian Conundrum12/8/08
Leonard seeks Penny's counsel when his relationship with Stephanie takes off faster than he'd like. Sheldon's hypochondriac tendencies get the better of him. - Ep 9The White Asparagus Triangulation11/24/08
Sheldon is overexuberant that Leonard finally has a girlfriend matching his high standards. - Ep 8The Lizard-Spock Expansion11/17/08
Sheldon wants to use an alternate version of rock-paper-scissors to help resolve conflicts. A girl Wolowitz has a major crush on falls for Leonard. - Ep 7The Panty Piñata Polarization11/10/08
When Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate. Howard and Raj search for the America's Next Top Model house. - Ep 6The Cooper-Nowitzki Theorem11/3/08
Sheldon, and his friends, are mystified when a younger undergraduate student is attracted to him. - Ep 5The Euclid Alternative10/20/08
An intervention is used to try to force Sheldon to overcome his fear of driving. - Ep 4The Griffin Equivalency10/13/08
Full of confidence following being named one of People's "30 to Watch Under 30", Raj hits on Penny and becomes impossibly arrogant. - Ep 3The Barbarian Sublimation10/6/08
Penny becomes addicted to an online game based on the world of Conan the Barbarian and persistantly pesters Sheldon for advice. - Ep 2The Codpiece Topology9/29/08
Seeing Penny with another guy sends Leonard back to Leslie Winkle, much to Sheldon's dismay. - Ep 1The Bad Fish Paradigm9/22/08
Penny opens up to a reluctant Sheldon after a less-than-stellar first date with Leonard, placing him in the uncomfortable position of having to keep a secret.
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Season 1
- Ep 17The Tangerine Factor5/19/08
Penny's break-up spurs Leonard to summon the courage to ask her out, and each goes to Sheldon for advice on their upcoming date. - Ep 16The Peanut Reaction5/12/08
Penny wants to throw a surprise party for Leonard, but Sheldon's indulgence at an electronics store throws her off-track. - Ep 15The Pork Chop Indeterminacy5/5/08
The rest of the gang fall for Sheldon's twin sister, and Leonard's plan to win her heart is derailed when Sheldon declares he'll be the one to decide who can date her. - Ep 14The Nerdvana Annihilation4/28/08
When the delivery of a full-size prop of 1960's The Time Machine makes Penny miss work, she scolds Leonard about his sci-fi collectibles. He decides it's time to give up such childish pursuits. - Ep 13The Bat Jar Conjecture4/21/08
Sheldon finds himself booted from the gang's Physics Bowl team and replaced with Leslie, so he forms his own team, hoping to prove he's superior. - Ep 12The Jerusalem Duality4/14/08
With Sheldon rattled and impossible to be around after meeting Dennis, a 15-year-old physicist who's smarter than he, the rest of the guys search for a way to eliminate the threat. - Ep 11The Pancake Batter Anomaly3/31/08
With his friends knowing how sour he acts when sick—and avoiding him as a result—Sheldon is nursed for by Penny, who hasn't a clue what she's in for. - Ep 10The Loobenfeld Decay3/24/08
Leonard and Sheldon each lie to avoid hearing Penny sing in a production of Rent. However, Sheldon's lie becomes a bit too complicated for its own good. - Ep 9The Cooper-Hofstadter Polarization3/17/08
When they're invited to present at a physics conference, Sheldon's reluctance to share the credit leads to a tiff between him and Leonard, and Penny's intervention only exacerbates the situation. - Ep 8The Grasshopper Experiment11/12/07
Raj's parents set him up on a blind date, and when he discovers he can talk to her, she shows interest in Sheldon. - Ep 7The Dumpling Paradox11/5/07
With Wolowitz AWOL with one of her friends, Penny's recruited to fill in for him on the guys' Halo team. - Ep 6The Middle Earth Paradigm10/29/07
Penny hosts a Halloween party, putting Leonard, Sheldon, Wolowitz, and Koothrappali through a new test of their social skills. - Ep 5The Hamburger Postulate10/22/07
Fearing he's wasting his time on Penny, Leonard ends up making a connection with Leslie. Meanwhile, Sheldon frets over a change to his hamburger routine. - Ep 4The Luminous Fish Effect10/15/07
Sheldon's getting fired forces him to explore what life has to offer outside physics, leaving Leonard to take drastic action to snap his friend out of his funk. - Ep 3The Fuzzy Boots Corollary10/8/07
Leonard asks a woman out after he finds out that Penny is seeing someone. - Ep 2The Big Bran Hypothesis10/1/07
Leonard volunteers to sign for a package in an attempt to make a good impression on Penny, but when he enlists Sheldon for help, his attempt at chivalry goes terribly awry. - Ep 1Pilot9/24/07
Brilliant physicist roommates Leonard and Sheldon meet their new neighbor Penny, who begins showing them that as much as they know about science, they know little about actual living.
