The Big Bang Theory

Season 1

S01E01Pilot 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. S01E02The 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. S01E03The Fuzzyboots Corollary Leonard asks a woman out after he finds out that Penny is seeing someone. S01E04The 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. S01E05The Hamburger Postulate Fearing he's wasting his time on Penny, Leonard ends up making a connection with Leslie. S01E06The Middle Earth Paradigm Penny hosts a Halloween party, putting Leonard, Sheldon, Wolowitz, and Koothrappali through a new test of their social skills. S01E07The Dumpling Paradox With Wolowitz AWOL with one of her friends, Penny's recruited to fill in for him on the guys' Halo team S01E08The 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. S01E09The 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. S01E10The 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. S01E11The 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. S01E12The 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. S01E13The 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. S01E14The 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. S01E15The 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. S01E16The Peanut Reaction Penny wants to throw a surprise party for Leonard, but Sheldon's indulgence at an electronics store throws her off-track. S01E17The 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.

Season 2

S02E01The Bad Fish Paradigm Penny's first date with Leonard goes awry; Penny finds Sheldon to be an unwilling confidant. S02E02The Codpiece Topology A jealous Leonard reacts to Penny's new guy by rebounding with Leslie. S02E03The Barbarian Sublimation Sheldon creates a monster when he introduces Penny to online gaming. S02E04The Griffin Equivalency Raj gets an inflated ego and makes a play for Penny after being referenced in a magazine article. S02E05The Euclid Alternative Leonard and his friends stage an intervention to force Sheldon to face his fear of driving. S02E06The Cooper-Nowitzki Theorem Sheldon and the gang are confused when a young grad student is attracted to him. S02E07The Panty Piñata Polarization When Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate. S02E08The Lizard-Spock Expansion Leonard inadvertently steals away the new woman Wolowitz thinks is the love of his life. S02E09The White Asparagus Triangulation Sheldon is thrilled when Leonard starts dating a woman who meets Sheldon's stringent standards. S02E10The Vartabedian Conundrum Leonard asks Penny for advice when his new relationship starts moving too fast. S02E11The 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. S02E12The 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. S02E13The Friendship Algorithm Sheldon creates a scientific procedure for making friends. S02E14The Financial Permeability Sheldon's solution to Penny's financial difficulty leads to a confrontation between Leonard and Penny's ex-boyfriend. S02E15The Maternal Capacitance Leonard and Penny are drawn together after a disastrous visit from Leonard's mother. S02E16The Cushion Saturation A paintball game leads to a fight between Sheldon and Penny, and romance for Leslie and Wolowitz. S02E17The 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. S02E18The Work Song Nanocluster Penny's home business turns into a complete nightmare when Sheldon takes over. S02E19The Dead Hooker Juxtaposition Penny squares off with a new beautiful female neighbor who may become the building's "new Penny." S02E20The Hofstadter Isotope A fellow comic book enthusiast's hitting on Penny leads to Leonard and Howard going to a bar's Ladies' Night. S02E21The 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. S02E22The 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. S02E23The Monopolar Expedition The guys' plan to work over the summer at the North Pole makes Penny revaluate her feelings for Leonard.

Season 3

S03E01The 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. S03E02The 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. S03E03The 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. S03E04The 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. S03E05The 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. S03E06The 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. S03E07The Guitarist Amplification A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism. S03E08The Adhesive Duck Deficiency With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on. S03E09The 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. S03E10The 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. S03E11The 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. S03E12The 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. S03E13The Bozeman Reaction When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system. S03E14The Einstein Approximation Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny. S03E15The 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. S03E16The Excelsior Acquisition Sheldon winds up in traffic court when he gets a ticket because of Penny. S03E17The Precious Fragmentation When the guys find a ring from "The Lord of the Rings" at a garage sale, it threatens to tear them apart. S03E18The Pants Alternative Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award. S03E19The Wheaton Recurrence A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling. S03E20The Spaghetti Catalyst When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy. S03E21The Plimpton Stimulation Leonard and Sheldon compete for the attention of a famous female physicist. S03E22The Staircase Implementation Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator. S03E23The Lunar Excitation While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.

Season 4

S04E01The Robotic Manipulation Penny tags along on Sheldon's first ever date; Wolowitz finds a new use for a robotic arm. S04E02The 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. S04E03The Zazzy Substitution The guys are concerned as Sheldon searches for an alternative to human companionship. S04E04The Hot Troll Deviation An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work. S04E05The Desperation Emanation Leonard realizes he’s the only one without a girlfriend, while Sheldon wants to get rid of his. S04E06The Irish Pub Formulation Leonard keeps an affair a secret from Sheldon, Howard and Raj. S04E07The Apology Insufficiency Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy. S04E08The 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. S04E09The Boyfriend Complexity Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope. S04E10The 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. S04E11The 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. S04E12The Bus Pants Utilization Leonard's idea for a smartphone app derails his friendship with Sheldon. S04E13The Love Car Displacement Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz. S04E14The 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. S04E15The Benefactor Factor A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science. S04E16The Cohabitation Formulaton As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister. S04E17The Toast Derivation Sheldon becomes concerned when everybody begins to hang out at Raj's apartment and discovers Leonard is the center of the group. S04E18The 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. S04E19The 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. S04E20The 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. S04E21The 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. S04E22The Wildebeest Implementation Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend. S04E23The Engagement Reaction When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital. S04E24The Roommate Transmogrification When Bernadette receives her PhD, Wolowitz feels emasculated. Raj and Leonard swap places and Penny does something she's regrets.

Season 5

S05E01The 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. S05E02The 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. S05E03The Pulled Groin Extrapolation Leonard and Amy get to know each other better, while Howard and Bernadette spend the weekend with Mrs. Wolowitz. S05E04The Wiggly Finger Catalyst Penny plays Matchmaker for Raj, which results in him finding a girl he is comfortable talking to. S05E05The 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. S05E06The 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. S05E07The 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. S05E08The Isolation Permutation Amy becomes heartbroken when she discovers that Penny and Bernadette went wedding dress shopping without her. S05E09The 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. S05E10The 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. S05E11The Speckerman Recurrence Leonard must face his fears after being contacted by his high school tormentor. S05E12The 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. S05E13The 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. S05E14The 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. S05E15The Friendship Contraction Sheldon's selfish demands force Leonard to reconsider their friendship. Meanwhile, Wolowitz tries to pick his astronaut nickname. S05E16The Vacation Solution When Sheldon is forced to take his vacation, he goes to work with Amy in her neurobiology lab. S05E17The Rothman Disintegration Sheldon battles Kripke for a coveted office at the university. Penny receives a very unusual gift from Amy. S05E18The 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. S05E19The Weekend Vortex Sheldon must choose between joining Amy at her aunt's birthday party or playing videogames all weekend with the guys. S05E20The 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. S05E21The Hawking Excitation When Wolowitz gets to work with Stephen Hawking, Sheldon is willing to do anything to meet his hero. S05E22The Stag Convergence After the guys throw Howard a bachelor party, Bernadette reconsiders marrying him after learning about his sexual history. S05E23The 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. S05E24The 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.

Season 6

S06E01The 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. S06E02The 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. S06E03The 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. S06E04The 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. S06E05The Holographic Excitation The gang celebrates Halloween at Stuart’s comic book store. Meanwhile, Leonard seduces Penny with science. S06E06The 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. S06E07The 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. S06E08The 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. S06E09The Parking Spot Escalation When the University reassigns Sheldon’s parking spot to Wolowitz, their fight affects the whole gang. S06E10The 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. S06E11The Santa Simulation During a Dungeons and Dragons game, Sheldon revisits Christmas memories; Amy, Penny and Bernadette look for a date for Raj. S06E12The Egg Salad Equivalency When Sheldon is accused of sexual harassment, he ends up getting Raj, Leonard and Howard in trouble. S06E13The 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. S06E14The 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. S06E15The 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. S06E16The 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. S06E17The Monster Isolation After a bad date, Koothrappali decides to never leave his apartment; Penny's acting skills impress Sheldon. S06E18The Contractual Obligation Implementation Leonard, Sheldon and Howard give lectures on science to junior high students. The girls ditch work to go to Disneyland. Raj devises a date for Lucy that fixes their social anxiety problems. S06E19The Closet Reconfiguration Howard considers whether or not he should open a letter from his father; Penny and Leonard host a "grown-up" cocktail party. S06E20The Tenure Turbulence The girls get involved when Leonard, Sheldon and Raj compete for tenure at the University. S06E21The 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. S06E22The 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. S06E23The Love Spell Potential A date between Raj and Lucy takes both of them out of their comfort zones. After a trip to Las Vegas goes awry, the girls join in on a Dungeons and Dragons game, which causes Amy and Sheldon to re-evaluate their relationship. S06E24The Bon Voyage Reaction When Leonard receives an exciting opportunity to work overseas, Penny and Sheldon are thrown for a loop. Raj and Lucy's relationship comes to a crossroad.

Season 7

S07E01The Hofstadter Insufficiency With Leonard away, Sheldon and Penny spend quality time together sharing intimate secrets. Also, Wolowitz helps Raj get over his ex-girlfriend. S07E02The Deception Verification Leonard and Sheldon's friendship is tested; Howard's latest foray into helping his mother has some disastrous side effects. S07E03The Scavenger Vortex When the entire gang competes in a scavenger hunt designed by Raj, it brings out the best - and worst - in everyone. S07E04The Raiders Minimization Sheldon gets mad at Amy for ruining one of his favorite movies, Raj and Stuart try to make their online dating profiles more appealing, and Leonard tries to play the sympathy card with Penny. S07E05The 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. S07E06The 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. S07E07The Proton Displacement Sheldon seeks payback when Arthur "Professor Proton" Jeffries asks Leonard for help on a project instead of him. Raj gets upset at Howard for crashing his night with the girls. S07E08The 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-girlfriend, Lucy. S07E09The 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. S07E10The Discovery Dissipation Leonard has to deal with the fallout of disproving Sheldon's new scientific discovery. Raj spends a week at Howard and Bernadette's apartment. S07E11The Cooper Extraction While Sheldon is at home in Texas, the rest of the gang realizes how much he has changed their lives as they decorate the apartment Christmas tree. S07E12The 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, Raj and Stuart try to practice their social skills, and Sheldon navigates the intricacies of being funny. S07E13The 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. Also, Amy receives an unwanted attention from a co-worker. S07E14The 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 try to feel more mature by going to a fancy hotel for tea. S07E15The Locomotive Manipulation Sheldon and Amy take a train ride to Napa Valley with Howard and Bernadette on Valentine's Day. Leonard and Penny take Raj's dog to the vet when she accidentally eats some chocolate. S07E16The 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. S07E17The Friendship Turbulence After arguing with Sheldon, Howard tries to make amends by taking him to NASA headquarters in Houston. Penny has second thoughts about quitting her waitressing job when her car dies. Amy gets involved in trying to find Raj a date. S07E18The 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. S07E19The 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. S07E20The 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. S07E21The 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. S07E22The Proton Transmogrification As the gang celebrates Star Wars Day, Sheldon has difficulty dealing with the recent death of Arthur "Professor Proton" Jeffries. S07E23The 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. S07E24The 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 caretaker for his mother. With his entire world changing around him, Sheldon considers a major move.

Season 8

S08E01The 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. S08E02The Junior Professor Solution Sheldon is forced to teach a class as a Junior Professor and Howard decides to enroll in it. Meanwhile, Amy plays both sides when tension arises between Penny and Bernadette. S08E03The 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. S08E04The 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. S08E05The Focus Attenuation The girls head to Las Vegas for some weekend fun, while the guys try to invent something cool, but only come up with new ways to procrastinate. S08E06The 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. Meanwhile, Leonard and Penny seek advice from Howard and Bernadette after they fight about money. S08E07The 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. S08E08The Prom Equivalency The girls decide to re-enact their high school proms with the guys. While Sheldon feels under pressure to commit to his relationship with Amy, Howard worries about who Stuart will bring as his date. S08E09The 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. S08E10The 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 finds out what her colleagues really think of her. S08E11The 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. S08E12The Space Probe Disintegration Howard 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. S08E13The Anxiety Optimization When Sheldon becomes stuck in a rut with his work, the gang tries to help him by raising his stress levels. Howard teases Raj with a game called "Emily or Cinnamon?" S08E14The 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. S08E15The Comic Book Store Regeneration Howard 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. S08E16The Intimacy Acceleration As a joke, Sheldon and Penny try an experiment designed to make participants fall in love. Meanwhile, 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. S08E17The Colonization Application A trip to the pet store ends in a fight after Amy learns Sheldon has applied for a one-way mission to colonize Mars. Meanwhile, Leonard surprises Penny with a very "adult" purchase, and Raj gets into trouble when he snoops around Emily's apartment. S08E18The 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. S08E19The 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. S08E20The Fortification Implementation When Sheldon and Amy build a blanket fort, they come to major crossroads in their relationship. Also, Howard meets the half-brother he never knew he had. Meanwhile, Penny is invited to appear on Wil Wheaton’s podcast, but things turn awkward when Leonard joins them. S08E21The 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. S08E22The Graduation Transmission Howard 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. S08E23The 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. S08E24The Commitment Determination As Sheldon presses Leonard and Penny to set a wedding date, he encounters major changes in his own relationship with Amy. Meanwhile, Raj contemplates breaking up with Emily, and Howard and Bernadette struggle with asking Stuart to move out of their house.

Season 9

S09E01The 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. S09E02The 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. S09E03The 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. S09E04The 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. S09E05The 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. S09E06The 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. S09E07The 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. S09E08The 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 on her. S09E09The 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. S09E10The 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". S09E11The 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. S09E12The 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. S09E13The Empathy Optimization After having to deal with a sick Sheldon, Leonard, Penny and the gang try to treat themselves to a Sheldon-free weekend. S09E14The 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. S09E15The 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. S09E16The 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. S09E17The Celebration Experimentation After more than nine years together, the gang finally celebrates Sheldon’s birthday, surprising him with a special guest. S09E18The 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. S09E19The 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. S09E20The 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. S09E21The 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. S09E22The 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. S09E23The 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. S09E24The 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.

Season 10

S10E01The 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. S10E02The Military Miniaturization Colonel Williams, an Air Force representative from the Department of Material Command sits down to talk with Wolowitz. S10E03The 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. S10E04The 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. S10E05The 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. S10E06The 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. S10E07The 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. S10E08The 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. S10E09The 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. S10E10The 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. S10E11The Birthday Synchronicity Howard and Bernadette welcome their new baby and Sheldon and Amy celebrate Amy’s birthday. S10E12The 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. S10E13The 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. S10E14The 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. S10E15The 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. S10E16The 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. S10E17The 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. S10E18The Escape Hatch Identification When Raj moves out of his apartment, Leonard and Penny offer him Sheldon's old room. S10E19The Collaboration Fluctuation Leonard, Penny and Raj adjust to their new living arrangement, and Sheldon takes an interest in Amy’s work. S10E20The 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. S10E21The 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. S10E22The Cognition Regeneration Leonard isn’t thrilled when Penny considers taking a new job offered by her ex-boyfriend, Zack. S10E23The 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. S10E24The Long Distance Dissonance The gang is concerned when Sheldon’s former admirer, Dr. Ramona Nowitzki, resurfaces while Amy is away at Princeton.

Season 11

S11E01The Proposal Proposal In the eleventh season opener, Amy gives Sheldon an answer to his proposal while Howard and Bernadette struggle with some unexpected news. S11E02The 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. S11E03The Relaxation Integration Sheldon and Amy struggle with picking a wedding date, which stresses out Sheldon and causes him talking in his sleep. Meanwhile, Raj and Stuart fight over the attention of one of Bernadette's co-workers. S11E04The 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. S11E05The Collaboration Contamination Sheldon and Raj confide in Bernadette when they can't handle Amy and Howard working together on a science project. Also, Penny and Leonard learn new tactics for how to deal with Sheldon from an unlikely source. S11E06The 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 Howard both wind up on bed rest. S11E07The Geology Methodology Sheldon and Bert collaborate on a research project, despite Sheldon’s embarrassment. Also, Penny and Bernadette coach Raj on how to navigate his relationship with Ruchi. S11E08The Tesla Recoil Leonard and Howard 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 that Ruchi might be trying to take over her projects at work. S11E09The 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. S11E10The Confidence Erosion Sheldon and Amy try to eliminate stress from wedding planning by applying math to the process. Also, Raj “breaks up” with Howard after realizing his best friend is actually hurting his confidence. S11E11The Celebration Reverberation Raj and Howard's feud continues as the gang plan Halley's first birthday party. Sheldon's surprise for Amy's birthday goes awry when they get food poisoning. Also, Leonard gets a Christmas letter from his brother that causes him to spiral out about his own lack of accomplishments. S11E12The Matrimonial Metric Sheldon and Amy try to pick their Best-Man and Maid of Honor by experimenting on the gang. S11E13The 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. S11E14The Separation Triangulation Raj 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. S11E15The Novelization Correlation Leonard's book raises questions, and Amy guest stars on the new Professor Proton show. S11E16The Neonatal Nomenclature When Bernadette won't go into labor, the gang tries different tactics to get things started. Also, Howard confronts Bernadette after Amy accidentally reveals she's already chosen their son's name. S11E17The Athenaeum Allocation Leonard jumps through hoops to help secure the perfect wedding venue for Sheldon and Amy. Also, Bernadette and Howard have a hard time deciding who should stay at home with the kids and who should go back to work. S11E18The Gates Excitation Bill Gates visits Penny's work, and the gang schemes to meet him. Hilarity ensues. Meanwhile, Sheldon is convinced that he's a target of an April's Fools prank. S11E19The Tenant Disassociation When Leonard learns Sheldon is the president of the tenants association, he decides to run against him. Also, Bernadette encourages Howard and Raj to find the owner of a drone after they find it in the backyard. S11E20The 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. S11E21The Comet Polarization Sheldon’s comic book store experience changes when writer Neil Gaiman puts Stuart’s store on the map. Also, friendships are threatened when Raj takes credit for Penny's astronomical discovery. S11E22The 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. S11E23The 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, Howard and Raj with pinkeye. S11E24The 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.

Season 12

S12E01The 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. S12E02The 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. S12E03The Procreation Calculation The Wolowitzes' life gets complicated when Stuart starts bringing his new girlfriend home. Also, Penny and Leonard talk about starting a family, while Raj explores an arranged marriage. S12E04The 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. S12E05The 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. S12E06The 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. S12E07The 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. S12E08The 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. S12E09The Citation Negation Sheldon and Amy are devastated after learning from a Russian paper that Super Asymmetry has already been theorized and disproven. Meanwhile, ultra-competitive Bernadette asks Stuart’s girlfriend to teach her how to beat Howard in a popular video game. S12E10The 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. S12E11The Paintball Scattering Penny and Leonard organize a paintball game that results in mayhem when Sheldon is jealous of Amy. Also, Raj catches Anu with her ex-boyfriend, and Stuart gets cold feet when Denise hints at the possibility of them living together. S12E12The Propagation Proposition Penny runs into her ex-boyfriend, Zack, who invites her and Leonard to a dinner to meet his newlywed wife. After the dinner the newlywed couple make an odd proposition to Leonard, which makes Penny to freak out. Also, Raj attempts to mend things with his ex-fiancée, Anu. S12E13The 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. Also, Bernadette gets one of her drugs approved at work and wants a reluctant Penny to head the sales team. S12E14The 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. S12E15The 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. S12E16The 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. S12E17The 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. S12E18The 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 causes opportunity and conflict at the Wolowitz home. S12E19The 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, Howard and Raj try to relive the good old days after Howard buys a scooter that looks like the one he had years ago. S12E20The Decision Reverberation Raj 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. S12E21The 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. Meanwhile, Howard learns that Bernadette wasn't the only waitress at the Cheesecake Factory who had a crush on him. S12E22The 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. S12E23The Change Constant Sheldon and Amy await big news. Meanwhile, Penny and Leonard have some big news of their own. Also, Howard and Bernadette face the stressful challenge of leaving their kids for the first time and Raj makes a new friend, as the gang travels together into an uncharted future. S12E24The Stockholm Syndrome 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.