The Big Bang Theory

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  • Next Air Date: Unknown
  • Genres: Comedy
  • Rating: 6.8/10, from 3665 ratings
  • Created By: Chuck Lorre, Bill Prady

The Big Bang Theory is centered on five characters living in Pasadena, California: roommates Leonard Hofstadter and Sheldon Cooper; Penny, a waitress and aspiring actress who lives across the hall; and Leonard and Sheldon's equally geeky and socially awkward friends and co-workers, mechanical engineer Howard Wolowitz and astrophysicist Raj Koothrappali. The geekiness and intellect of the four guys is contrasted for comic effect with Penny's social skills and common sense.

The Big Bang Theory Season 12

Episode 24 - Aired 2019-05-16
Unraveling the Mystery: A Big Bang Farewell

Johnny Galecki and Kaley Cuoco will lead fans on a trip down memory lane, sharing some of the best-kept backstage secrets and personal memories from the past 12 years.

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Episode 23 - Aired 2019-05-16
The Change Constant / The Stockholm Syndrome

Sheldon and Amy await big news.

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Episode 22 - Aired 2019-05-09
The Maternal Conclusion

Leonard is pleasantly surprised when Beverly comes to visit and she's genuinely kind to him, until he finds out the real reason she's there. Also, Denise and Stuart overstay their welcome at the Wolowitz house.

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Episode 21 - Aired 2019-05-02
The Plagiarism Schism

Kripke has proof that Dr. Pemberton plagiarized his thesis in college, and Sheldon and Amy aren't sure if they should turn him in or not; Wolowitz learns that Bernadette wasn't the only waitress at the Cheesecake Factory who had a crush on him.

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Episode 20 - Aired 2019-04-25
The Decision Reverberation

Koothrappali is worried people won’t take him seriously in his own field after publishing a paper that suggests he may have discovered alien life. Also, Leonard wants to be the principal investigator on a plasma physics study.

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Episode 19 - Aired 2019-04-18
The Inspiration Deprivation

The concept of what it would mean for women everywhere if Amy were to win a Nobel Prize causes Amy to have a meltdown. Also, Koothrappali and Wolowitz try to relive the good old days after Wolowitz buys a scooter that looks like the one he had years ago.

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Episode 18 - Aired 2019-04-04
The Laureate Accumulation

When competitors Pemberton and Campbell charm America on a publicity tour, Sheldon and Amy try to bring Nobel laureates Kip Thorne, George Smoot and Frances Arnold to their side. Also, Halley's fear of the dark leads to opportunity and conflict for Howard, Bernadette and Stuart.

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Episode 17 - Aired 2019-03-07
The Conference Valuation

When Penny and Bernadette go to San Diego for a pharmaceutical sales convention, Wolowitz is in charge of the kids. Also, Sheldon finds a book on experimenting on kids, and the guys plus Amy make a day of it.

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Episode 16 - Aired 2019-02-21
The D & D Vortex

The gang finds out Wil Wheaton hosts a celebrity Dungeons and Dragons game involving William Shatner, Joe Manganiello, Kareem Abdul-Jabbar and Kevin Smith. Deception and betrayal are the path to make it to the one open seat.

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Episode 15 - Aired 2019-02-07
The Donation Oscillation

Penny tries to seduce an abstaining Leonard to ruin his "donation" for her ex-boyfriend, Zack, and his wife, Marissa. Also, Wolowitz, Bernadette, Anu and Koothrappali turn Koothrappali's canceled bachelor party into a couple's trip.

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Episode 14 - Aired 2019-01-31
The Meteorite Manifestation

Sheldon is thrilled to help Bernadette and Wolowitz navigate bureaucratic paperwork, until he discovers they are breaking the law. Also, Leonard is disappointed when his friends exclude him from a scientific project.

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Episode 13 - Aired 2019-01-17
The Confirmation Polarization

Sheldon and Amy are thrilled when their super asymmetry theory is proven by two physicists, until they try to kick Amy off the Nobel nomination; Bernadette has a big success at work.

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Episode 12 - Aired 2019-01-10
The Propagation Proposition

Penny’s ex-boyfriend, Zack, and his wife want a baby, but when Zack is infertile, they ask Leonard for help. Also, Koothrappali attempts to mend things with his ex-fiancée, Anu.

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Episode 11 - Aired 2019-01-03
The Paintball Scattering

Penny and Leonard organize a paintball game that results in mayhem when Sheldon is jealous of Amy. Also, Koothrappali catches Anu with her ex-boyfriend, and Stuart doesn’t want to move in with Denise.

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Episode 10 - Aired 2018-12-06
The VCR Illumination

Sheldon and Amy are still down about their theory being disproven, but a VHS tape from Sheldon’s past inspires him not to give up. Bernadette turns into a pageant mom when she tries to help Howard ace his Magic Castle audition.

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Episode 9 - Aired 2018-11-15
The Citation Negation

Sheldon and Amy are devastated after learning from a Russian paper that Super Asymmetry has already been discovered and disproven. Ultra-competitive Bernadette asks Stuart’s girlfriend to teach her how to beat Howard in a popular video game.

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Episode 8 - Aired 2018-11-08
The Consummation Deviation

Sheldon tries to bond with Amy's father, but when Howard lures Mr. Fowler away with magic tricks, Sheldon has no choice but to bond with Mrs. Fowler. Raj and Anu try to get physical for the first time.

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Episode 7 - Aired 2018-11-01
The Grant Allocation Derivation

Leonard is caught between a rock and a hard place when he's responsible for distributing extra grant money. Bernadette turns the backyard playhouse into a hideaway from Howard and the kids.

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Episode 6 - Aired 2018-10-25
The Imitation Perturbation

When Howard dresses up as Sheldon for Halloween, Sheldon seeks retaliation at Leonard and Penny's Halloween party. Leonard is shocked that Penny doesn't remember their first kiss.

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Episode 5 - Aired 2018-10-18
The Planetarium Collision

When Amy doesn’t have time to work on super-asymmetry, Sheldon goes to great lengths to ensure she’s available to work with him even it if means accidentally sabotaging her career in the process. Raj doesn’t want Howard to join him in hosting a show at the planetarium.

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Episode 4 - Aired 2018-10-11
The Tam Turbulence

When Sheldon won't tell anyone why he's never mentioned his childhood best friend, Leonard takes matters into his own hands. Bernadette and Penny take out Raj’s fiancée for dinner to get the skinny on her.

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Episode 3 - Aired 2018-10-04
The Procreation Calculation

The Wolowitzes' life gets complicated when Stuart starts bringing his new girlfriend home. Penny and Leonard talk about starting a family. Raj explores an arranged marriage.

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Episode 2 - Aired 2018-09-27
The Wedding Gift Wormhole

Sheldon and Amy drive themselves crazy trying to figure out what 'perfect gift' Leonard and Penny gave them for their wedding. Raj decides he wants to settle down and asks his father to arrange a marriage for him.

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Episode 1 - Aired 2018-09-24
The Conjugal Configuration

Sheldon and Amy's honeymoon runs aground in New York. Penny and Leonard discover they are uncomfortably similar to Amy's parents. Raj insults physicist Neil deGrasse Tyson and starts a Twitter war.

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The Big Bang Theory Season 11

After years of only looking out for himself, Sheldon found Amy Farrah Fowler to be the most patient woman to ever walk the earth, and... they did it! Wedding fever continues in season 11.

Episode 24 - Aired 2018-05-10
The Bow Tie Asymmetry

When Amy's parents and Sheldon's family arrive, everybody is focused to make sure all wedding arrangements go according to plan – everyone except the bride and groom.

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Episode 23 - Aired 2018-05-03
The Sibling Realignment

When Sheldon learns that his mother won’t attend his wedding unless he invites his brother, Georgie, he and Leonard travel to Texas to end a family feud. Also, the Wolowitz kids inadvertently infest Amy, Bernadette, Wolowitz and Koothrappali with pinkeye.

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Episode 22 - Aired 2018-04-26
The Monetary Insufficiency

Sheldon goes to Vegas to win money for science. Also, Penny and Bernadette take Amy wedding dress shopping, but her terrible choice entangles them in a web of lies.

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Episode 21 - Aired 2018-04-19
The Comet Polarization

Sheldon’s comic book store experiences changes when writer Neil Gaiman puts Stuart’s store on the map. Also, Koothrappali takes credit for Penny’s astronomical discovery, and friendships are threatened.

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Episode 20 - Aired 2018-04-12
The Reclusive Potential

A brilliant but reclusive scientist, Doctor Wolcott, invites Sheldon to his cabin in the middle of nowhere, and Leonard, Raj and Howard go along for the trip. Also, Penny and Bernadette improvise after Amy doesn’t like the tame bachelorette party they planned for her.

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Episode 19 - Aired 2018-04-05
The Tenant Disassociation

When Leonard learns Sheldon is the president of the tenants association, he decides to run against him. Also, Bernadette encourages Wolowitz and Koothrappali to find the owner of a drone after they find it in the backyard.

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Episode 18 - Aired 2018-03-29
The Gates Excitation

Bill Gates visits Penny's work, and the gang schemes to meet him. Hilarity ensues.

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Episode 17 - Aired 2018-03-08
The Athenaeum Allocation

Leonard jumps through hoops to help secure the perfect wedding venue for Sheldon and Amy. Also, Bernadette and Wolowitz have a hard time deciding who should stay at home with the kids and who should go back to work.

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Episode 16 - Aired 2018-03-01
The Neonatal Nomenclature

When Bernadette won't go into labor, the gang tries different tactics to get things started. Howard confronts Bernadette after Amy accidentally reveals she's already chosen their son's name.

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Episode 15 - Aired 2018-02-01
The Novelization Correlation

Leonard's book raises questions, and Amy guest stars on the new Professor Proton show.

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Episode 14 - Aired 2018-01-18
The Separation Triangulation

Koothrappali finds himself in the middle of domestic drama when he learns the woman he's dating, has a very upset husband. Also, when Sheldon rents his old room back for a quiet place to work, he drives Leonard crazy by being a model tenant.

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Episode 13 - Aired 2018-01-11
The Solo Oscillation

When Sheldon kicks Amy out to work solo, she and Leonard bond during a series of science experiments. Also, Bert the geologist replaces Wolowitz in the band Footprints on the Moon, and Sheldon finds Penny a surprising source of scientific inspiration.

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Episode 12 - Aired 2018-01-04
The Matrimonial Metric

Sheldon and Amy will try to use science to see who should be their Maid of Honor and Best Man.

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Episode 11 - Aired 2017-12-14
The Celebration Reverberation

Sheldon and Wolowitz plan birthday celebrations for Amy and Halley, respectively. Also, Leonard get a Christmas letter from his brother that causes him to spiral out about his own lack of accomplishments.

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Episode 10 - Aired 2017-12-07
The Confidence Erosion

Sheldon and Amy try to eliminate stress from wedding planning by applying math to the process. Also, Koothrappali “breaks up” with Wolowitz after realizing his best friend is actually hurting his confidence.

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Episode 9 - Aired 2017-11-30
The Bitcoin Entanglement

Sheldon tries to teach the guys a lesson after they cut him out of a potentially valuable Bitcoin investment. Also, a seven-year-old video reveals a secret about Leonard and Penny's relationship.

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Episode 8 - Aired 2017-11-16
The Tesla Recoil

Leonard and Wolowitz are furious after they learn Sheldon went to work with the military behind their backs. Also, while Bernadette is on bed rest, she asks Raj to do some digging when she suspects Ruchi is trying to steal her job.

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Episode 7 - Aired 2017-11-09
The Geology Methodology

Sheldon and Bert collaborate on a research project, despite Sheldon’s embarrassment. Also, Penny and Bernadette coach Koothrappali on how to navigate his relationship with Ruchi.

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Episode 6 - Aired 2017-11-02
The Proton Regeneration

Sheldon goes head-to-head with Wil Wheaton for the role of the new Professor Proton. Also, Penny steps in to take care of Halley when Bernadette and Wolowitz both wind up on bed rest.

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Episode 5 - Aired 2017-10-23
The Collaboration Contamination

Sheldon and Koothrappali confide in Bernadette when they can't handle Amy and Wolowitz working together. Also, Penny and Leonard learn new tactics for how to deal Sheldon from an unlikely source.

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Episode 4 - Aired 2017-10-16
The Explosion Implosion

As Howard worries about fatherhood, he and Sheldon bond when they jointly assemble a model rocket. Meanwhile, Penny bonds with Leonard's mother, Beverly, much to his concern.

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Episode 3 - Aired 2017-10-09
The Relaxation Integration

Sheldon struggles with picking a wedding date. Amy decides she wants a wedding near a cliff which Sheldon doesn't want. Meanwhile Raj and Stuart fight over one of Bernadette's co-workers.

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Episode 2 - Aired 2017-10-02
The Retraction Reaction

Leonard angers the university – and the entire physics community – after he gives an embarrassing interview. Also, Amy and Bernadette bond over having to hide their success from Sheldon and Howard.

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Episode 1 - Aired 2017-09-25
The Proposal Proposal

In the eleventh season opener, Amy gives Sheldon an answer to his proposal while Howard and Bernadette struggle with some unexpected news.

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The Big Bang Theory Season 10

Leonard and Penny renew their vows, this time inviting their friends and family for wedding party; they also learn that marriage is about compromise, and figure out how to support each other. Sheldon and Amy experiment to take their relationship to the next level, and after an emotional struggle they move in together in Penny's old apartment. Howard and Bernadette realise that being a parent is a full-time job, but with the help of their friends they manage to find joy in raising their child. When his friends tell him he's extremely spoiled, Raj decides to stop taking his father's money and learn how to make ends meet.

Episode 24 - Aired 2017-05-11
The Long Distance Dissonance

The gang is concerned when Sheldon’s former admirer, Dr. Ramona Nowitzki, resurfaces while Amy is away at Princeton.

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Episode 23 - Aired 2017-05-04
The Gyroscopic Collapse

After Leonard, Sheldon and Wolowitz celebrate the completion of the top secret air force project, they are met with an unpleasant surprise. Also, Amy is offered a summer position as a visiting researcher.

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Episode 22 - Aired 2017-04-27
The Cognition Regeneration

Leonard isn’t thrilled when Penny considers taking a new job offered by her ex-boyfriend, Zack.

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Episode 21 - Aired 2017-04-13
The Separation Agitation

Howard and Bernadette have a hard time leaving Halley in day care when Bernadette returns to work. Also, Bert introduces the gang to his new girlfriend, Rebecca.

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Episode 20 - Aired 2017-04-06
The Recollection Dissipation

Sheldon pushes himself to the limit when he collaborates on projects with Leonard and Wolowitz as well as Amy on the same day. Also, Bernadette is nearing the end of her maternity leave and must return to work.

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Episode 19 - Aired 2017-03-30
The Collaboration Fluctuation

Leonard, Penny and Raj adjust to their new living arrangement, and Sheldon takes an interest in Amy’s work.

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Episode 18 - Aired 2017-03-09
The Escape Hatch Identification

When Raj moves out of his apartment, Leonard and Penny offer him Sheldon's old room.

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Episode 17 - Aired 2017-02-23
The Comic-Con Conundrum

With Koothrappali cut off from his father’s fortune, he appoints Sheldon to help him get out of debt. Also, Penny considers joining Leonard at Comic-Con.

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Episode 16 - Aired 2017-02-16
The Allowance Evaporation

Sheldon and Amy have their first fight since moving in together, and Koothrappali is shocked at the realities of financial independence when he stops receiving support from his father.

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Episode 15 - Aired 2017-02-09
The Locomotion Reverberation

Leonard and Wolowitz try to distract Sheldon when he slows the progress of their guidance system. Also, Penny and Amy take Bernadette out for the night, leaving Raj and Stuart to care for baby Halley.

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Episode 14 - Aired 2017-02-02
The Emotion Detection Automation

Sheldon beta-tests an MIT invention after hearing it can help him read people’s emotions. Also, Leonard can’t hide his feelings when Penny announces her brother is coming to town, and Raj invites his ex-girlfriends over to give him dating advice.

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Episode 13 - Aired 2017-01-19
The Romance Recalibration

When Penny feels that Leonard is taking her for granted, she decides to go on a spa weekend with Amy. Also, Wolowitz and Koothrappali try to fix a squeaky floorboard in the baby’s room.

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Episode 12 - Aired 2017-01-05
The Holiday Summation

Sheldon and Amy visit Leonard and Penny for the first time since the holidays and share details about their terrible trip to Texas.

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Episode 11 - Aired 2016-12-15
The Birthday Synchronicity

Howard and Bernadette welcome their new baby and Sheldon and Amy celebrate Amy’s birthday.

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Episode 10 - Aired 2016-12-01
The Property Division Collision

Sheldon and Leonard try to divvy up their shared belongings, but can’t agree on anything. Also, Koothrappali and Stuart fight to be the most helpful during Bernadette’s final weeks of pregnancy.

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Episode 9 - Aired 2016-11-17
The Geology Elevation

When Bert, a Caltech geologist, wins the MacArthur Genius fellowship, Sheldon is overcome with jealousy. Also, Wolowitz finds an old remote control Stephen Hawking action figure he invented.

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Episode 8 - Aired 2016-11-10
The Brain Bowl Incubation

After a successful experiment combining their genes, Sheldon will stop at nothing to convince Amy they should procreate. Also, Koothrappali is embarrassed to tell the gang what the new woman he’s dating does for a living.

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Episode 7 - Aired 2016-11-03
The Veracity Elasticity

In order to continue living with Sheldon, Amy lies to him about repairs being made to her apartment and they host an "on location" episode of "Fun With Flags" in Penny’s apartment. Also, Leonard lets Penny decorate Sheldon’s old room after he learns that she has been secretly moving Leonard’s collectibles into storage.

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Episode 6 - Aired 2016-10-27
The Fetal Kick Catalyst

Penny is surprised to learn she has fans of her performance in "Serial Ape-ist" when she attends Van Nuys Comic Con with Leonard. Also, Amy hosts a Sheldon-style brunch at Penny’s apartment, and Wolowitz makes an impulsive purchase when he starts stressing out about the baby on the way.

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Episode 5 - Aired 2016-10-17
The Hot Tub Contamination

Leonard and Penny must separate a quarreling Sheldon and Amy when their cohabitation does not go as planned, and Sheldon threatens to break off their relationship when Amy refuses to adhere to the bathroom schedule. Also, Howard and Bernadette find unexpected guests at their house when they decide to stay home from a planned vacation.

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Episode 4 - Aired 2016-10-10
The Cohabitation Experimentation

When Amy’s apartment floods, she proposes a “cohabitation experiment” with Sheldon. Also, Howard and Bernadette are upset when Koothrappali learns the gender of the baby before they do.

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Episode 3 - Aired 2016-10-03
The Dependence Transcendence

Tensions rise when the boys struggle to complete their government project on time and Sheldon tries an energy drink to stay awake. Also, Penny and Amy go to a “party” at Bert the geologist’s house, and Koothrappali learns Bernadette’s true feelings about her pregnancy when they clean out the future baby room.

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Episode 2 - Aired 2016-09-26
The Military Miniaturization

Colonel Williams, an Air Force representative from the Department of Material Command sits down to talk with Wolowitz.

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Episode 1 - Aired 2016-09-19
The Conjugal Conjecture

After Sheldon’s mother and Leonard's father share an evening together, everyone deals with an awkward morning the next day. Also, Penny’s family arrives for the wedding ceremony, including her anxiety-ridden mother, Susan, and her drug dealing brother, Randall.

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The Big Bang Theory Season 9

Our two genius roommates, Leonard and Sheldon, and their friends are back once again (smarter, but no wiser). Last season, Sheldon went soul-searching (on a train, of course) and was prepared to make some substantial revisions on his Relationship Agreement with Amy, when everything changed. Leonard, meanwhile, was off to Vegas with Penny to finally tie the knot in the season finale. Howard finds himself alone with Bernadette after the sudden passing of his mother; while Raj is not only talking to women – he’s getting exclusive with Emily. Together, they will all learn that life is far more complicated outside of the lab as love and friendship never produce predictable results!

Episode 24 - Aired 2016-05-12
The Convergence Convergence

Chaos ensues when Leonard’s recently divorced parents, Alfred and Beverly, and Sheldon’s devoutly religious mother, Mary, come to town. Also, Wolowitz and Koothrappali think the government is out to get them when they are contacted about their guidance system.

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Episode 23 - Aired 2016-05-05
The Line Substitution Solution

Sheldon hires Stuart to spend the day with Amy when he’d rather go to a movie screening. Also, Leonard’s mother, Beverly, comes to town and Penny struggles to make a connection with her.

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Episode 22 - Aired 2016-04-28
The Fermentation Bifurcation

The gang goes to a wine bar and runs into Penny’s old boyfriend, Zack. Also, Bernadette gets stuck spending the evening with Sheldon when she can’t go wine tasting with the group, and things don’t go as planned when Koothrappali introduces his new girlfriend, Claire.

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Episode 21 - Aired 2016-04-21
The Viewing Party Combustion

Everyone must choose sides when a small argument between Leonard and Sheldon erupts into a heated fight during a group get-together.

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Episode 20 - Aired 2016-04-07
The Big Bear Precipitation

Sheldon spills a secret of Leonard’s when the two take a weekend cabin trip with Penny and Amy. Also, when Koothrappali goes overboard with pregnancy gifts, Wolowitz and Bernadette must draw the line.

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Episode 19 - Aired 2016-03-31
The Solder Excursion Diversion

Amy is shocked at a revelation from Sheldon after she buys him a new laptop. Also, Koothrappali sells out Leonard and Wolowitz after they lie to their wives in order to attend an early screening of a movie.

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Episode 18 - Aired 2016-03-10
The Application Deterioration

Leonard, Sheldon, and Wolowitz run into problems when they file for a patent for their infinite persistence gyroscope. Also, Penny, Amy and Bernadette give Koothrappali dating advice when Emily reaches out to him after their breakup.

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Episode 17 - Aired 2016-02-25
The Celebration Experimentation

After more than nine years together, the gang finally celebrates Sheldon’s birthday, surprising him with a special guest.

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Episode 16 - Aired 2016-02-18
The Positive Negative Reaction

When the gang finds out about Bernadette’s pregnancy, they celebrate by singing karaoke. Also, Bernadette is concerned when Wolowitz freaks out over her pregnancy announcement, and Wolowitz is convinced he must make more money to provide for the baby.

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Episode 15 - Aired 2016-02-11
The Valentino Submergence

Sheldon and Amy host a live Valentine's Day episode of Fun with Flags, Leonard and Penny grapple with getting older, Howard and Bernadette find a surprise in their hot tub and Raj is torn between Emily and the cute girl he met at the Comic Bookstore.

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Episode 14 - Aired 2016-02-04
The Meemaw Materialization

Meemaw meets Amy, but it isn't all roses. Meemaw seems to have an axe to grind with her. Sheldon comes to Amy's defense, but not before Meemaw lets a little secret of his slip.

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Episode 13 - Aired 2016-01-14
The Empathy Optimization

After having to deal with a sick Sheldon, Leonard, Penny and the gang try to treat themselves to a Sheldon-free weekend.

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Episode 12 - Aired 2016-01-07
The Sales Call Sublimation

Penny gets more than she bargained for when Leonard agrees to meet with a psychiatrist on her behalf. Also, Sheldon and Koothrappali collaborate on an astronomical discovery, and Wolowitz and Bernadette can't believe what they are feeling after Stuart moves out.

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Episode 11 - Aired 2015-12-17
The Opening Night Excitation

After more than five years of dating, Sheldon and Amy spend their first night together. Also, Leonard, Wolowitz, and Koothrappali must decide who will take their extra Star Wars movie ticket.

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Episode 10 - Aired 2015-12-10
The Earworm Reverberation

Sheldon has a revelation when he realizes why a song was stuck in his head. Also, Amy invites Dave over for dinner despite their previously awkward date, and Wolowitz and Koothrappali become obsessed with a fan of their band, "Footprints on the Moon".

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Episode 9 - Aired 2015-11-19
The Platonic Permutation

Sheldon and Amy try hanging out as friends when they spend Thanksgiving together at the aquarium. Also, Wolowitz reluctantly agrees to volunteer at the soup kitchen with Bernadette, Raj and Emily, and Penny discovers that Leonard knows more about her than she thought.

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Episode 8 - Aired 2015-11-12
The Mystery Date Observation

Sheldon, Wolowitz and Koothrappali post an online advertisement to find Sheldon a new girlfriend. Also, when Amy is coy with details about a guy she is dating, Penny and Bernadette decide to spy

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Episode 7 - Aired 2015-11-05
The Spock Resonance

Wil Wheaton interviews Sheldon for a Star Trek documentary where he reveals the ring and his plan to propose to Amy. Bernadette wants to start renovating the house and the topic of starting a family together with Howard is brought up.

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Episode 6 - Aired 2015-10-26
The Helium Insufficiency

In the midst of a nation-wide helium shortage, Sheldon and Leonard take desperate measures to get the supplies they need. Also, Penny and Bernadette download a dating app on Amy's phone to try and find her a new man.

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Episode 5 - Aired 2015-10-19
The Perspiration Implementation

The guys take a fencing lesson from Barry Kripke and Sheldon finds himself in an awkward position when Kripke expresses interest in Amy. Also, when Stuart struggles to get female customers at the Comic Book Store, Penny, Amy and Bernadette come by to help him out.

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Episode 4 - Aired 2015-10-12
The 2003 Approximation

Sheldon learns of an impending change in his living arrangements and decides to revert back to 2003, a simpler time before he met Leonard and Penny. Also, Howard and Raj form a band to play at the Comic Book Store.

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Episode 3 - Aired 2015-10-05
The Bachelor Party Corrosion

The guys' science skills are put to the test when they get a flat tire during Leonard's bachelor party weekend in Mexico. Also, the girls force Penny to finally tell her family that she eloped with Leonard.

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Episode 2 - Aired 2015-09-28
The Separation Oscillation

Leonard confronts the woman he kissed on the North Sea in an attempt to set Penny's mind at ease. Also, Sheldon films a special episode of "Fun with Flags" after his breakup with Amy, and Bernadette feels guilty about withholding a secret from Penny.

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Episode 1 - Aired 2015-09-21
The Matrimonial Momentum

After driving to Vegas to get married, Penny struggles with Leonard’s confession that he kissed another girl. Also, Sheldon doesn't know how to act after Amy pushes pause on their relationship.

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The Big Bang Theory Season 8

Sheldon is rescued from his soul-searching cross-country train trip (older but no wiser) and that means The Big Bang Theory gang's all here to spread another gear's cheer as TV's most attended laugh seminar. Enrol in the comic curriculum to observe Leonard's minor surgery, which signals a major catastrophe for Sheldon, Howard's obsession over his mum's relationship with friend-turned-freeloader Stuart and the unexpected results of Penny's technique as a pharmaceutical sales rep. Discover ways to re-create proms not attended or holiday celebrations not especially beloved and play a new game based on Raj's dating life. Savour online fan Fiction by Amy, watch Bernadette take indelicate command of some delicate family matters and, who knows, you might spot a cool special guest or two.

Episode 24 - Aired 2015-05-07
The Commitment Determination

Sheldon pushes Leonard and Penny to choose a date for their wedding and deals with dramatic changes in his own relationship with Amy.

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Episode 23 - Aired 2015-04-30
The Maternal Combustion

Personalities collide when Sheldon and Leonard’s mothers finally meet. Meanwhile, Howard finally decides to “man up” and do his fair share of the housework – but not without a little help from his friends.

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Episode 22 - Aired 2015-04-23
The Graduation Transmission

Wolowitz questions his engineering abilities when he and Sheldon can’t get a toy drone to fly. Meanwhile, a cancelled flight nearly prevents Leonard from giving the commencement address at his former high school, and Raj pits his parents against each other when his father cuts him off financially.

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Episode 21 - Aired 2015-04-16
The Communication Deterioration

When Raj is asked to create a message in case a NASA mission discovers alien life, the guys fight over what he should do. Also, Penny is torn between auditioning for a movie or keeping her successful pharmaceutical sales job.

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Episode 20 - Aired 2015-04-09
The Fortification Implementation

When Sheldon and Amy build a blanket fort, they come to major crossroads in their relationship. Also, Wolowitz meets the half-brother he never knew he had, and when Penny is invited to appear on Wil Wheaton’s podcast, she and Leonard have a huge, on-air argument.

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Episode 19 - Aired 2015-04-02
The Skywalker Incursion

When Leonard and Sheldon are invited to speak at UC Berkeley, they take a detour to try to meet an idol. Also, when Bernadette and Howard battle over the fate of his Doctor Who TARDIS, Raj and Amy offer to settle the dispute with a game of ping pong.

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Episode 18 - Aired 2015-03-12
The Leftover Thermalization

Friction ensues when a magazine fails to mention Leonard in an article about the paper he co-wrote with Sheldon. Also, a blackout at Mrs. Wolowitz’s home leads to a final family dinner in her honor.

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Episode 17 - Aired 2015-03-05
The Colonization Application

Trouble arises when Amy learns Sheldon has applied for a one-way mission to colonize Mars. Also, a trip to the pet store ends in a fight for Sheldon and Amy, Leonard surprises Penny with a very “adult” purchase, and Raj is caught snooping in Emily’s apartment.

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Episode 16 - Aired 2015-02-26
The Intimacy Acceleration

As a joke, Sheldon and Penny try an experiment designed to make participants fall in love. Also, Leonard, Amy, Raj and Emily spend the evening trying to escape a room with a “zombie.” And, after returning from Mrs. Wolowitz’ funeral, Bernadette and Howard run into trouble at the airport.

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Episode 15 - Aired 2015-02-19
The Comic Book Store Regeneration

Wolowitz receives some shocking news as everyone prepares for the reopening of Stuart’s comic book store. Penny teaches Sheldon how to “let it go,” but can’t follow her own advice after she learns something infuriating about Amy. Also, Leonard and Raj think they spot Nathan Fillion at a restaurant.

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Episode 14 - Aired 2015-02-05
The Troll Manifestation

Leonard and Sheldon publish a paper which is widely accepted except for comments from an internet troll. Meanwhile, the girls reminisce about embarrassing incidents from their past.

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Episode 13 - Aired 2015-01-29
The Anxiety Optimization

The gang tries to help Sheldon when he becomes stuck in a rut at work by increasing his anxiety level. Howard teases Raj with a new game called "Cinnamon or Emily?"

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Episode 12 - Aired 2015-01-08
The Space Probe Disintegration

Wolowitz tries to distract Raj, who is anxiously awaiting data from a space probe he helped launch. Meanwhile, Sheldon and Leonard go dress shopping with Penny and Amy.

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Episode 11 - Aired 2014-12-11
The Clean Room Infiltration

Leonard and Howard turn to Raj for help in dealing with a work emergency when they nearly come to blows after blaming each other for a potential disaster at the university. Amy throws an authentic Victorian Christmas party, while Sheldon seeks revenge on her for making him celebrate the holidays.

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Episode 10 - Aired 2014-11-20
The Champagne Reflection

While Sheldon says a tearful goodbye to the final installment of "Fun with Flags", Leonard, Howard and Raj search for something significant in a dead professor's research. And Bernadette is shocked to learn of her co-workers’ true feelings from Penny.

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Episode 9 - Aired 2014-11-13
The Septum Deviation

When Leonard gets minor surgery on his nose, Sheldon is the one in need of sympathy. Meanwhile, Raj's parents' impending divorce causes Howard and Bernadette to work on their own marriage.

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Episode 8 - Aired 2014-11-06
The Prom Equivalency

When the gang recreates a high-school prom night on the roof of the guys'; apartment building, Sheldon feels pressure to participate in all the typical romantic traditions.

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Episode 7 - Aired 2014-10-30
The Misinterpretation Agitation

The guys try to help Penny out of an awkward work dilemma, when a smitten doctor shows up at her door after her flirtatious sales techniques work a little too well. Meanwhile, Amy and Bernadette argue over whether or not female scientists should play up their sexuality.

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Episode 6 - Aired 2014-10-20
The Expedition Approximation

Sheldon and Raj test whether they could survive a dark-matter research expedition in a salt mine by simulating the conditions in a steam tunnel deep underground. Leonard and Penny seek advice from Howard and Bernadette after they fight about money.

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Episode 5 - Aired 2014-10-13
The Focus Attenuation

During their weekend in Las Vegas, Bernadette and Amy accuse Penny of being a buzz kill. The guys try to invent the next big thing.

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Episode 4 - Aired 2014-10-06
The Hook-Up Reverberation

Raj's honesty comes back to haunt him when his new girlfriend is unfriendly to Penny. The guys think about becoming part owners in Stuart's store.

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Episode 3 - Aired 2014-09-29
The First Pitch Insufficiency

Wolowitz feels nervous when he is asked to throw the first pitch at a Los Angeles Angels game. Penny and Leonard want to prove Sheldon wrong after he says he and Amy are the better couple.

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Episode 2 - Aired 2014-09-22
The Junior Professor Solution

When Sheldon must teach a class, Howard decides to take it. Amy takes advantage of the tension between Penny and Bernadette.

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Episode 1 - Aired 2014-09-22
The Locomotion Interruption

Leonard and Amy make an unexpected trip to Arizona to fetch Sheldon; Penny interviews for a job at Bernadette's company; Stuart's relationship with Mrs. Wolowitz disturbs Howard.

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The Big Bang Theory Season 7

Leonard returns from his North Sea expedition to find that his relationship with Penny involves more beta-testing than he’s ever done in a lab. Howard’s attachment issues with the women in his life in particular and Raj’s social breakthrough with women in general provide more laughs. Bernadette and Amy stand staunchly by the men in their life, even when they’re sitting in marathon role-playing games. Sheldon sees his mom in a totally different way, parties with James Earl Jones, establishes a (sort of) bond with his idol Professor Proton and makes a scientific breakthrough that breaks down before you can say Science Friday.

Episode 24 - Aired 2014-05-15
The Status Quo Combustion

Sheldon get upset about his career, the destruction of the comic book store and Leonard and Penny's future living arrangements. Howard and Bernadette can't keep hold of a carer for his mother. With his entire world changing around him, Sheldon considers a major move.

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Episode 23 - Aired 2014-05-08
The Gorilla Dissolution

A bad day causes Penny to reevaluate her life choices – including Leonard. Meanwhile, Howard and Bernadette struggle to care for Mrs. Wolowitz, and Raj gets relationship advice from Sheldon.

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Episode 22 - Aired 2014-05-01
The Proton Transmogrification

As the gang celebrates Star Wars Day, Sheldon discovers he is having difficulty dealing with the death of Professor Proton.

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Episode 21 - Aired 2014-04-24
The Anything Can Happen Recurrence

To prepare for a date with Emily, Howard acclimates Raj to horror movies. Penny and Sheldon are upset when they discover Amy and Bernadette lied to avoid hanging out with them.

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Episode 20 - Aired 2014-04-10
The Relationship Diremption

Sheldon faces a personal crisis after deciding he’s wasting his time with string theory. Meanwhile, a double date between Raj, Emily and the Wolowitzes ends in embarrassment for Howard.

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Episode 19 - Aired 2014-04-03
The Indecision Amalgamation

While Raj is wracked with guilt when he tries to date two women at once, Penny wrestles with whether to take a role in a cheesy movie and Sheldon is torn trying to choose between two gaming systems.

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Episode 18 - Aired 2014-03-13
The Mommy Observation

When Sheldon visits his Mom in Houston, he is forced to confront a new reality. Meanwhile, Raj’s ‘Murder Mystery’ party starts some fights within the gang.

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Episode 17 - Aired 2014-03-06
The Friendship Turbulence

Bernadette tries to negotiate peace between Sheldon and Wolowitz; Penny receives an embarrassing offer; Raj wants Amy to write to a woman on his behalf.

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Episode 16 - Aired 2014-02-27
The Table Polarization

Leonard buys a dining room table and it causes Sheldon to reevaluate the changes in his life. Meanwhile, Wolowitz is offered a chance to go back to space and Bernadette struggles with whether or not to encourage him.

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Episode 15 - Aired 2014-02-06
The Locomotive Manipulation

Sheldon and Amy go on a trip to wine country with Howard and Bernadette; Penny and Leonard rush Raj's dog to the vet.

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Episode 14 - Aired 2014-01-30
The Convention Conundrum

After the guys can’t get Comic-Con tickets, Sheldon tries to hold his own convention and winds up spending a wild night with James Earl Jones. Meanwhile, the girls see if they can act like “grown-ups”.

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Episode 13 - Aired 2014-01-09
The Occupation Recalibration

Sheldon tries to relax after he is forced to take a vacation. Meanwhile, Leonard struggles to be supportive of Penny after she quits her job, and Bernadette seeks Stuart’s help in replacing one of Howard’s comic books.

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Episode 12 - Aired 2014-01-02
The Hesitation Ramification

When Penny’s big acting break on NCIS is a bust, Leonard struggles to help her, which results in Penny asking Leonard a bold relationship question. Meanwhile, Sheldon tries to learn how to be funny and Raj tries to work on his “game” before talking to girls.

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Episode 11 - Aired 2013-12-12
The Cooper Extraction

While Sheldon is in Texas, the rest of the gang realizes how much he has changed their lives as they decorate the apartment Christmas tree.

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Episode 10 - Aired 2013-12-05
The Discovery Dissipation

Leonard and Amy help Sheldon cope with the shame he’s feeling after his accidental contribution to science is disproved. Meanwhile, Raj must stay with Howard and Bernadette for a week.

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Episode 9 - Aired 2013-11-21
The Thanksgiving Decoupling

Sheldon protests when the gang drags him to Mrs. Wolowitz’s house for Thanksgiving. Meanwhile, Penny and Leonard must deal with a mistake from her past.

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Episode 8 - Aired 2013-11-14
The Itchy Brain Simulation

When a mistake comes to light, Sheldon makes Leonard walk a mile in his shoes; Penny decides to confront Raj's ex.

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Episode 7 - Aired 2013-11-07
The Proton Displacement

When Professor Proton asks Leonard for help with an experiment, Sheldon retaliates by befriending Proton's rival, Bill Nye.

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Episode 6 - Aired 2013-10-24
The Romance Resonance

Sheldon's latest scientific breakthrough leaves him feeling like a fraud; a romantic gesture between Howard and Bernadette causes Penny to up her game with Leonard.

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Episode 5 - Aired 2013-10-17
The Workplace Proximity

Amy starts working at Caltech which causes friction with Sheldon. Howard agrees with Sheldon who mentions this to Bernadette causing a big fight for the Wolowitzes.

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Episode 4 - Aired 2013-10-10
The Raiders Minimization

Beverly Hofstadter writes a psychology book about Leonard which Penny buys and reads. Sheldon wants to ruin something for Amy after she ruins an Indiana Jones movie for him. Raj and Stuart try online dating.

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Episode 3 - Aired 2013-10-03
The Scavenger Vortex

When the entire gang competes in a scavenger hunt designed by Raj, it brings out the best - and worst - in everyone.

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Episode 2 - Aired 2013-09-26
The Deception Verification

Leonard and Sheldon's friendship is tested; Wolowitz's relationship with his mom causes a threat to his masculinity.

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Episode 1 - Aired 2013-09-26
The Hofstadter Insufficiency

With Leonard away, Sheldon and Penny spend quality time together sharing intimate secrets. Also, Wolowitz helps Raj get over his ex-girlfriend.

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The Big Bang Theory Season 6

Whether on or above Earth, hilarity is outrageously universal in TV's most popular comedy featuring four forward-thinking but socially backward geniuses. Fun discoveries multiply: Leonard learns jealousy is bad for a relationship (with Penny) but science is good for seduction (of Penny). Howard finds life in the International Space Station life is no escape from terrestrial turmoil between his mom and his new wife Bernadette. Raj meets someone special who may be a good match, if he can keep her from fleeing mid-date. And then there's Sheldon. He learns what not to say after facing harassment charges or competing for tenure at work and how Dungeons & Dragons can be the icebreaker his relationship with Amy needs.

Episode 24 - Aired 2013-05-16
The Bon Voyage Reaction

When Leonard receives an exciting opportunity to work overseas, Penny and Sheldon are thrown for a loop.

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Episode 23 - Aired 2013-05-09
The Love Spell Potential

Amy and Sheldon's relationship takes a surprising turn during a game of "Dungeons & Dragons"; Lucy and Koothrappali have an awkward date.

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Episode 22 - Aired 2013-05-02
The Proton Resurgence

Leonard and Sheldon hire the host (Bob Newhart) of their favorite childhood TV show to perform; Bernadette and Howard run into trouble while dog-sitting for Raj's pet.

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Episode 21 - Aired 2013-04-25
The Closure Alternative

Amy tries to help Sheldon get over his compulsive need for closure when one of his favorite TV shows is canceled; Raj discovers a secret about Lucy.

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Episode 20 - Aired 2013-04-04
The Tenure Turbulence

The girls get involved when Leonard, Sheldon and Raj compete for tenure at the University.

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Episode 19 - Aired 2013-03-14
The Closet Reconfiguration

Howard considers whether or not he should open a letter from his father; Penny and Leonard host a "grown-up" cocktail party.

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Episode 18 - Aired 2013-03-07
The Contractual Obligation Implementation

Leonard, Sheldon and Wolowitz talk to junior high girls about science-related careers; Raj plans a date with Lucy.

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Episode 17 - Aired 2013-02-21
The Monster Isolation

After a bad date, Koothrappali decides to never leave his apartment; Penny's acting skills impress Sheldon.

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Episode 16 - Aired 2013-02-14
The Tangible Affection Proof

The guys search for a perfect Valentine's Day gift for their significant others; Stuart and Raj host a "lonely people" party at the comic book store.

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Episode 15 - Aired 2013-02-07
The Spoiler Alert Segmentation

A fight between Sheldon and Leonard impacts Amy and Penny's living arrangements; while Howard is away, Raj helps Mrs. Wolowitz out.

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Episode 14 - Aired 2013-01-31
The Cooper/Kripke Inversion

Sheldon faces a crisis of confidence when he is forced to work with his nemesis, Barry Kripke; Raj and Howard buy expensive action figures of themselves.

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Episode 13 - Aired 2013-01-10
The Bakersfield Expedition

As the guys don costumes and go on a road trip to a comic book convention, the ladies decide to stay home and try to interpret a comic book.

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Episode 12 - Aired 2013-01-03
The Egg Salad Equivalency

When Sheldon is accused of sexual harassment, he ends up getting Raj, Leonard and Wolowitz in trouble.

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Episode 11 - Aired 2012-12-13
The Santa Simulation

During a game, Sheldon revisits Christmas memories; Amy, Penny and Bernadette look for a date for Koothrappali.

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Episode 10 - Aired 2012-12-06
The Fish Guts Displacement

When Amy gets sick, Sheldon tries to nurse her back to health; Wolowitz and his father-in-law plan a fishing trip.

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Episode 9 - Aired 2012-11-29
The Parking Spot Escalation

When the University reassigns Sheldon’s parking spot to Wolowitz, their fight affects the whole gang.

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Episode 8 - Aired 2012-11-15
The 43 Peculiarity

Raj and Howard try to to figure out why Sheldon disappears at 2:45 every afternoon; jealousy arises in Penny and Leonard's relationship.

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Episode 7 - Aired 2012-11-08
The Habitation Configuration

Wolowitz struggles with moving out of his mother’s house. Meanwhile, Sheldon is caught in the middle of an argument between Amy and Wil Wheaton.

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Episode 6 - Aired 2012-11-01
The Extract Obliteration

Sheldon’s relationship with Stephen Hawking is threatened over a game of “Words with Friends,” and Penny secretly enrolls in a class at the local college.

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Episode 5 - Aired 2012-10-25
The Holographic Excitation

The gang celebrates Halloween at Stuart’s comic book store. Meanwhile, Leonard seduces Penny with science.

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Episode 4 - Aired 2012-10-18
The Re-Entry Minimization

When Wolowitz returns from space, he doesn’t get the hero’s welcome he expected. Meanwhile, Game Night turns into a battle of the sexes.

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Episode 3 - Aired 2012-10-11
The Higgs Boson Observation

Amy feels threatened when Sheldon hires a young female assistant, and the pressure of being in space takes its toll on Wolowitz.

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Episode 2 - Aired 2012-10-04
The Decoupling Fluctuation

When Sheldon learns that Penny is thinking about breaking up with Leonard, he tries to intervene. Meanwhile, in space, the other astronauts pick on Howard.

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Episode 1 - Aired 2012-09-27
The Date Night Variable

With his friends on dates, Raj must face his loneliness. Also, Wolowitz is caught in an argument between Bernadette and his mom, even while he’s in space

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The Big Bang Theory Season 5

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.

Episode 24 - Aired 2012-05-10
The Countdown Reflection

The 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.

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Episode 23 - Aired 2012-05-03
The Launch Acceleration

When 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.

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Episode 22 - Aired 2012-04-26
The Stag Convergence

After the guys throw Howard a bachelor party, Bernadette reconsiders marrying him after learning about his sexual history.

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Episode 21 - Aired 2012-04-05
The Hawking Excitation

When Wolowitz gets to work with Stephen Hawking, Sheldon is willing to do anything to meet his hero.

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Episode 20 - Aired 2012-03-29
The Transporter Malfunction

Penny 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.

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Episode 19 - Aired 2012-03-08
The Weekend Vortex

Sheldon must choose between joining Amy at her aunt's birthday party or playing videogames all weekend with the guys.

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Episode 18 - Aired 2012-02-23
The Werewolf Transformation

Sheldon 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.

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Episode 17 - Aired 2012-02-16
The Rothman Disintegration

Penny is horrified when Amy gives her a gift: a huge, quite horrible painting of the two of them. With no good way to avoid displaying it, she only hangs it up when Amy is over. When Amy catches her taking the painting down, she's embarrassed and angry until Penny lies and says the gift made Bernadette jealous. When the deranged Professor Rothman is forced to retire, both Sheldon and Kripke vie for his office. President Siebert refuses to resolve the dispute, so Leonard arranges a one-on-one basketball game to decide (since they're both equally bad at sports). Neither one can even make a single basket, so they end up deciding by seeing who can bounce the ball the highest. Sheldon wins; unfortunately, the office is not what he'd hoped for: the thermostat is located in the office of a professor going through the hot flashes of menopause (thus Sheldon is too cold), the mockingbird outside his window is off-key with the annoying windchimes, the perpetually naked Professor Rothman refuses to vacate, and the Geology Department upstairs makes too much noise. Finally, Sheldon gets his head stuck in the wall in an existing hole, after which Leonard takes his picture before he goes for help.

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Episode 16 - Aired 2012-02-09
The Vacation Solution

When Sheldon is forced to take his vacation, he goes to work with Amy in her neurobiology lab.

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Episode 15 - Aired 2012-02-02
The Friendship Contraction

Sheldon's selfish demands force Leonard to reconsider their friendship. Meanwhile, Wolowitz tries to pick his astronaut nickname.

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Episode 14 - Aired 2012-01-26
The Beta Test Initiation

Leonard 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.

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Episode 13 - Aired 2012-01-19
The Recombination Hypothesis

Leonard, 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.

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Episode 12 - Aired 2012-01-12
The Shiny Trinket Maneuver

Sheldon 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.

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Episode 11 - Aired 2011-12-08
The Speckerman Recurrence

Leonard must face his fears after being contacted by his high school tormentor.

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Episode 10 - Aired 2011-11-17
The Flaming Spittoon Acquisition

When Stuart asks Amy out on a date, Sheldon must confront his feelings and consider where his relationship with Amy is going.

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Episode 9 - Aired 2011-11-10
The Ornithophobia Diffusion

Leonard 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.

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Episode 8 - Aired 2011-11-03
The Isolation Permutation

Amy becomes heartbroken when she discovers that Penny and Bernadette went wedding dress shopping without her.

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Episode 7 - Aired 2011-10-27
The Good Guy Fluctuation

A cute comic book artist puts Leonard and Priya’s relationship to the test, while Sheldon tries to scare the guys for Halloween.

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Episode 6 - Aired 2011-10-20
The Rhinitis Revelation

Sheldon'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.

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Episode 5 - Aired 2011-10-13
The Russian Rocket Reaction

Sheldon and Leonard get invited to a party at Wil Wheaton's house, and Howard gets an out-of-this-world opportunity.

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Episode 4 - Aired 2011-10-06
The Wiggly Finger Catalyst

Penny plays Matchmaker for Raj, which results in him finding a girl he is comfortable talking to.

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Episode 3 - Aired 2011-09-29
The Pulled Groin Extrapolation

Leonard and Amy get to know each other better, while Howard and Bernadette spend the weekend with Mrs. Wolowitz.

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Episode 2 - Aired 2011-09-22
The Infestation Hypothesis

A fight between Sheldon and Penny leaves Amy caught in the middle, while Leonard tries to spice up his long-distance relationship with Priya.

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Episode 1 - Aired 2011-09-22
The Skank Reflex Analysis

Penny 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.

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The Big Bang Theory Season 4

This season the Big Bang gang’s romantic universe expands. On the rebound from Penny, Leonard falls into the arms of Raj’s sister Priya. Sheldon gets a girlfriend, or rather a friend who is a girl: Amy, a dour neurobiologist who declares herself besties with Penny. Howard and Bernadette heat up. And so do Raj and Bernadette (at least in Raj’s Bollywood daydream).

Episode 24 - Aired 2011-05-19
The Roommate Transmogrification

When Bernadette receives her PhD, Wolowitz feels emasculated. Raj and Leonard swap places and Penny does something she's regrets.

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Episode 23 - Aired 2011-05-12
The Engagement Reaction

When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.

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Episode 22 - Aired 2011-05-05
The Wildebeest Implementation

Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.

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Episode 21 - Aired 2011-04-28
The Agreement Dissection

When Leonard spends too much time in the shower with Priya, Sheldon charges Leonard with two violations of the roommate agreement. However, before he can get too far, Priya uses her skills as a lawyer to nullify the charges due to the agreement's vague wording, much to Sheldon's dismay. When the guys take advantage of Priya's skills in order to eat Greek food on pizza night, Sheldon goes to Penny, who invites him to a girls' night out with Amy and Bernadette, which Sheldon agrees to after Penny mentions that they may be talking trash about Priya. After the girls drink some cocktails, they decide to take Sheldon dancing, which Sheldon reluctantly goes along with. After dancing, Sheldon takes an intoxicated Amy back to her apartment and as well as talking about Priya, meets a monkey who is addicted to smoking cigarettes. Amy tells Sheldon not to give in to Priya's law skills, before kissing him and going to her bathroom to vomit.

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Episode 20 - Aired 2011-04-07
The Herb Garden Germination

Sheldon and Amy decide to start several rumors about the others as a test. Meanwhile, Howard takes his relationship with Bernadette to even higher level.

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Episode 19 - Aired 2011-03-31
The Zarnecki Incursion

Sheldon's online-game account is hacked by Todd Zarnecki, who then proceeds to steal all his items prompting the guys to go on a quest to retrieve them. Penny, Bernadette and Amy discuss how Penny groomed Leonard to be willing to try various things and more adventurous boyfriend... for some other woman — Priya.

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Episode 18 - Aired 2011-03-10
The Prestidigitation Approximation

Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Leonard realizes dating Priya may make it impossible to continue being friends with Penny.

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Episode 17 - Aired 2011-02-24
The Toast Derivation

Sheldon becomes concerned when everybody begins to hang out at Raj's apartment and discovers Leonard is the center of the group.

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Episode 16 - Aired 2011-02-17
The Cohabitation Formulation

As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.

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Episode 15 - Aired 2011-02-10
The Benefactor Factor

A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science.

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Episode 14 - Aired 2011-02-03
The Thespian Catalyst

Hoping it will make him a better teacher, Sheldon has Penny give him acting lessons. Raj has fantasies about a friend's girlfriend.

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Episode 13 - Aired 2011-01-20
The Love Car Displacement

Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz.

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Episode 12 - Aired 2011-01-06
The Bus Pants Utilization

Leonard's idea for a smartphone app derails his friendship with Sheldon.

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Episode 11 - Aired 2010-12-16
The Justice League Recombination

The guys find a "super" use for Penny's new boyfriend, Zack, when they enter a costume contest as the Justice League.

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Episode 10 - Aired 2010-12-09
The Alien Parasite Hypothesis

Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.

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Episode 9 - Aired 2010-11-18
The Boyfriend Complexity

Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.

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Episode 8 - Aired 2010-11-11
The 21-second Excitation

While the guys camp in line for a long-awaited movie screening, Penny and Bernadette invite Amy to her first slumber party.

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Episode 7 - Aired 2010-11-04
The Apology Insufficiency

Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.

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Episode 6 - Aired 2010-10-28
The Irish Pub Formulation

Leonard keeps an affair a secret from Sheldon, Howard and Raj.

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Episode 5 - Aired 2010-10-21
The Desperation Emanation

Leonard realizes he’s the only one without a girlfriend, while Sheldon wants to get rid of his.

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Episode 4 - Aired 2010-10-14
The Hot Troll Deviation

An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work.

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Episode 3 - Aired 2010-10-07
The Zazzy Substitution

The guys are concerned as Sheldon searches for an alternative to human companionship.

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Episode 2 - Aired 2010-09-30
The Cruciferous Vegetable Amplification

Realizing he will not live long enough to download his consciousness into a robot body, Sheldon tries to extend his life span.

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Episode 1 - Aired 2010-09-23
The Robotic Manipulation

Penny tags along on Sheldon's first ever date; Wolowitz finds a new use for a robotic arm.

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The Big Bang Theory Season 3

Worlds collide in Season 3! A love affair with Penny has opened a big, wide, wonderful world of romance for Leonard. But Sheldon likes the world just the way it was, thank you. All of which makes for a zany comic triangle with brainy, clueless Sheldon and practical, grounded Penny hilariously vying for the role of hypotenuse.

Episode 23 - Aired 2010-05-24
The Lunar Excitation

While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.

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Episode 22 - Aired 2010-05-17
The Staircase Implementation

Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator.

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Episode 21 - Aired 2010-05-10
The Plimpton Stimulation

Leonard and Sheldon compete for the attention of a famous female physicist.

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Episode 20 - Aired 2010-05-03
The Spaghetti Catalyst

When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.

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Episode 19 - Aired 2010-04-12
The Wheaton Recurrence

A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.

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Episode 18 - Aired 2010-03-22
The Pants Alternative

Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.

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Episode 17 - Aired 2010-03-08
The Precious Fragmentation

When the guys find a ring from "The Lord of the Rings" at a garage sale, it threatens to tear them apart.

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Episode 16 - Aired 2010-03-01
The Excelsior Acquisition

Sheldon winds up in traffic court when he gets a ticket because of Penny.

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Episode 15 - Aired 2010-02-08
The Large Hadron Collision

Leonard can only bring one guest on a trip to see CERN's Large Hadron Collider (the world's largest and highest energy particle accelerator) in Switzerland on Valentine's Day.

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Episode 14 - Aired 2010-02-01
The Einstein Approximation

Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.

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Episode 13 - Aired 2010-01-18
The Bozeman Reaction

When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.

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Episode 12 - Aired 2010-01-11
The Psychic Vortex

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 mixer.

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Episode 11 - Aired 2009-12-14
The Maternal Congruence

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.

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Episode 10 - Aired 2009-12-07
The Gorilla Experiment

Penny gets help from Sheldon in order to understand what Leonard's work is, while Wolowitz develops a jealousy when Leonard starts hanging out with his new girlfriend.

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Episode 9 - Aired 2009-11-23
The Vengeance Formulation

After he's humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.

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Episode 8 - Aired 2009-11-16
The Adhesive Duck Deficiency

With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.

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Episode 7 - Aired 2009-11-09
The Guitarist Amplification

A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism.

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Episode 6 - Aired 2009-11-02
The Cornhusker Vortex

Sheldon becomes Leonard's teacher in order to understand football, while an incident with flying a kite threatens Howard and Raj's friendship.

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Episode 5 - Aired 2009-10-19
The Creepy Candy Coating Corollary

After overhearing that Wil Wheaton is entering a trading-card competition, Sheldon decides to enter it himself. Meanwhile, Penny sets up one of her friends on a date with Wolowitz.

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Episode 4 - Aired 2009-10-12
The Pirate Solution

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 a third wheel.

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Episode 3 - Aired 2009-10-05
The Gothowitz Deviation

Howard and Raj visit a Goth nightclub to pick up women while Sheldon attempts to build a better Penny using chocolate-based behavior modification.

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Episode 2 - Aired 2009-09-28
The Jiminy Conjecture

Leonard and Penny struggle to recover from an awkward first hookup while Sheldon and Howard stake their best comic books on a bet to determine the species of a cricket.

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Episode 1 - Aired 2009-09-21
The Electric Can Opener Fluctuation

When Sheldon learns the guys tampered with his expedition data he got from the arctic, he leaves to Texas in disgrace. This results in the guys following him, which threatens Leonard's hope for some romantic time with Penny and the guys' friendship with Sheldon.

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The Big Bang Theory Season 2

This season, Leonard gets a girl. So does Sheldon. Howard drives the Mars Rover into a ditch. Raj woos a terminator. Gorgeous girl-next-door Penny falls under the spell of Age of Conan. And super-smart, ueberconfident Leslie Winkler reduces mere men to spineless jellyfish.

Episode 23 - Aired 2009-05-11
The Monopolar Expedition

The guys' plan to work over the summer at the North Pole makes Penny revaluate her feelings for Leonard.

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Episode 22 - Aired 2009-05-04
The Classified Materials Turbulence

Penny's second date with Stuart sees her making a comment that gives Leonard new hope for a relationship with her. Wolowitz realizes there's a crucial error in a NASA project he's working on.

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Episode 21 - Aired 2009-04-27
The Vegas Renormalization

Leonard and Koothrappali escort a heartbroken Wolowitz to Las Vegas, and Sheldon becomes locked out of his apartment and must stay with Penny.

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Episode 20 - Aired 2009-04-13
The Hofstadter Isotope

A fellow comic book enthusiast's hitting on Penny leads to Leonard and Howard going to a bar's Ladies' Night.

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Episode 19 - Aired 2009-03-30
The Dead Hooker Juxtaposition

Penny squares off with a new beautiful female neighbor who may become the building's "new Penny."

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Episode 18 - Aired 2009-03-16
The Work Song Nanocluster

Penny's home business turns into a complete nightmare when Sheldon takes over.

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Episode 17 - Aired 2009-03-09
The Terminator Decoupling

Leonard, Sheldon and Wolowitz are ecstatic to learn that a famous science-fiction actress (Summer Glau) is on board the train they are taking to San Francisco.

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Episode 16 - Aired 2009-03-02
The Cushion Saturation

A paintball game leads to a fight between Sheldon and Penny, and romance for Leslie and Wolowitz.

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Episode 15 - Aired 2009-02-09
The Maternal Capacitance

Leonard and Penny are drawn together after a disastrous visit from Leonard's mother.

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Episode 14 - Aired 2009-02-02
The Financial Permeability

Sheldon's solution to Penny's financial difficulty leads to a confrontation between Leonard and Penny's ex-boyfriend.

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Episode 13 - Aired 2009-01-19
The Friendship Algorithm

Sheldon creates a scientific procedure for making friends.

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Episode 12 - Aired 2009-01-12
The Killer Robot Instability

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.

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Episode 11 - Aired 2008-12-15
The Bath Item Gift Hypothesis

Penny starts dating Leonard's handsome colleague; Leonard and his friends are tortured by Sheldon's obsession with gift-giving etiquette.

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Episode 10 - Aired 2008-12-08
The Vartabedian Conundrum

Leonard asks Penny for advice when his new relationship starts moving too fast.

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Episode 9 - Aired 2008-11-24
The White Asparagus Triangulation

Sheldon is thrilled when Leonard starts dating a woman who meets Sheldon's stringent standards.

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Episode 8 - Aired 2008-11-17
The Lizard-Spock Expansion

Leonard inadvertently steals away the new woman Wolowitz thinks is the love of his life.

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Episode 7 - Aired 2008-11-10
The Panty Piñata Polarization

When Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate.

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Episode 6 - Aired 2008-11-03
The Cooper-Nowitzki Theorem

Sheldon and the gang are confused when a young grad student is attracted to him.

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Episode 5 - Aired 2008-10-20
The Euclid Alternative

Leonard and his friends stage an intervention to force Sheldon to face his fear of driving.

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Episode 4 - Aired 2008-10-13
The Griffin Equivalency

Raj gets an inflated ego and makes a play for Penny after being referenced in a magazine article.

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Episode 3 - Aired 2008-10-06
The Barbarian Sublimation

Sheldon creates a monster when he introduces Penny to online gaming.

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Episode 2 - Aired 2008-09-29
The Codpiece Topology

A jealous Leonard reacts to Penny's new guy by rebounding with Leslie.

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Episode 1 - Aired 2008-09-22
The Bad Fish Paradigm

Penny's first date with Leonard goes awry; Penny finds Sheldon to be an unwilling confidant.

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The Big Bang Theory Season 1

University physicists Leonard and Sheldon know whether to use an integral or a differential to solve the area under a curve. But they don't have a clue about girls. Or dating. Or clothes. Or parties. Or having fun. Or, basically, life. So when a pretty blonde named Penny moves in the apartment across the hall, the guys decide to get an education outside of the classroom. Boys, you have a lot to learn.

Episode 17 - Aired 2008-05-19
The Tangerine Factor

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.

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Episode 16 - Aired 2008-05-12
The Peanut Reaction

Penny wants to throw a surprise party for Leonard, but Sheldon's indulgence at an electronics store throws her off-track.

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Episode 15 - Aired 2008-05-05
The Pork Chop Indeterminacy

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.

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Episode 14 - Aired 2008-04-28
The Nerdvana Annihilation

When delivery of another collectible leads to Penny's lashing out at Leonard, he decides it's time to give up his habit, much to his friends' protestation.

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Episode 13 - Aired 2008-04-21
The Bat Jar Conjecture

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.

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Episode 12 - Aired 2008-04-14
The Jerusalem Duality

With Sheldon rattled over meeting Dennis, a 15-year-old physicist who's smarter than he, Leonard helps him look for a way to debunk Dennis's research.

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Episode 11 - Aired 2008-03-31
The Pancake Batter Anomaly

With his friends knowing how sour he acts when sick—and avoiding him as a result—Sheldon is nursed by Penny, who hasn't a clue what she's in for.

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Episode 10 - Aired 2008-03-24
The Loobenfeld Decay

Leonard and Sheldon each lie to avoid seeing Penny's concert, but Sheldon's is a bit too complicated for his own good.

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Episode 9 - Aired 2008-03-17
The Cooper-Hofstadter Polarization

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.

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Episode 8 - Aired 2007-11-12
The Grasshopper Experiment

Raj's parents set him up on a blind date, but just when he discovers he can talk to her, she shows interest in Sheldon.

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Episode 7 - Aired 2007-11-05
The Dumpling Paradox

With Wolowitz AWOL with one of her friends, Penny's recruited to fill in for him on the guys' Halo team

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Episode 6 - Aired 2007-10-29
The Middle-Earth Paradigm

Penny hosts a Halloween party, putting Leonard, Sheldon, Wolowitz, and Koothrappali through a new test of their social skills.

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Episode 5 - Aired 2007-10-22
The Hamburger Postulate

Fearing he's wasting his time on Penny, Leonard ends up making a connection with Leslie.

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Episode 4 - Aired 2007-10-15
The Luminous Fish Effect

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.

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Episode 3 - Aired 2007-10-08
The Fuzzy Boots Corollary

Leonard asks a woman out after he finds out that Penny is seeing someone.

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Episode 2 - Aired 2007-10-01
The Big Bran Hypothesis

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.

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Episode 1 - Aired 2007-09-24
Pilot

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.

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