The Big Bang Theory

The Bad Fish Paradigm

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

The Codpiece Topology

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

The Barbarian Sublimation

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

The Griffin Equivalency

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

The Euclid Alternative

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

The Cooper-Nowitzki Theorem

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

The Panty Piñata Polarization

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

The Lizard-Spock Expansion

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

The White Asparagus Triangulation

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

The Vartabedian Conundrum

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

The Bath Item Gift Hypothesis

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

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 o

The Friendship Algorithm

Sheldon creates a scientific procedure for making friends.

The Financial Permeability

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

The Maternal Capacitance

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

The Cushion Saturation

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

The Terminator Decoupling

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

The Work Song Nanocluster

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

The Dead Hooker Juxtaposition

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

The Hofstadter Isotope

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

The Vegas Renormalization

Leonard and Koothrappali escort a heartbroken Wolowitz to Las Vegas, and Sheldon becomes locked out of his apartment and

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. Wolow

The Monopolar Expedition

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

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. T

The Jiminy Conjecture

Leonard and Penny struggle to recover from an awkward first hookup while Sheldon and Howard stake their best comic books

The Gothowitz Deviation

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

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 wit

The Creepy Candy Coating Corollary

After overhearing that Wil Wheaton is entering a trading-card competition, Sheldon decides to enter it himself. Meanwhil

The Cornhusker Vortex

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

The Guitarist Amplification

A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiatio

The Adhesive Duck Deficiency

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

The Vengeance Formulation

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

The Gorilla Experiment

Penny gets help from Sheldon in order to understand what Leonard's work is, while Wolowitz develops a jealousy when Leon

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

The Psychic Vortex

Leonard is aghast to find out a secret of Penny's: she believes in psychics. Meanwhile, Sheldon tries to assist Koothrap

The Bozeman Reaction

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

The Einstein Approximation

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

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 p

The Excelsior Acquisition

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

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.

The Pants Alternative

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

The Wheaton Recurrence

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

The Spaghetti Catalyst

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

The Plimpton Stimulation

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

The Staircase Implementation

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

The Lunar Excitation

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

The Robotic Manipulation

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

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

The Zazzy Substitution

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

The Hot Troll Deviation

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

The Desperation Emanation

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

The Irish Pub Formulation

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

The Apology Insufficiency

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

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 par

The Boyfriend Complexity

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

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 s

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.

The Bus Pants Utilization

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

The Love Car Displacement

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

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

The Benefactor Factor

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

The Cohabitation Formulation

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

The Toast Derivation

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

The Prestidigitation Approximation

Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Leonard realizes dating Priya may make it impossible to continu

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

The Herb Garden Germination

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

The Agreement Dissection

When Leonard spends too much time in the shower with Priya, Sheldon charges Leonard with two violations of the roommate

The Wildebeest Implementation

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

The Engagement Reaction

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

The Roommate Transmogrification

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

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 S

The Infestation Hypothesis

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

The Pulled Groin Extrapolation

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

The Wiggly Finger Catalyst

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

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.

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 gan

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

The Isolation Permutation

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

The Ornithophobia Diffusion

Leonard and Penny try hanging out as friends on a 'non-date', but end up purposely ruining each others chances with pers

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 g

The Speckerman Recurrence

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

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 wit

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 contemplat

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 wit

The Friendship Contraction

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

The Vacation Solution

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

The Rothman Disintegration

Sheldon battles Kripke for a coveted office at the university. Penny receives a very unusual gift from Amy.

The Werewolf Transformation

Sheldon becomes agitated when his regular barber is out sick. Astronaut training causes Howard to reconsider wanting to

The Weekend Vortex

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

The Transporter Malfunction

Penny buys Leonard and Sheldon “Star Trek” collectibles as a thank-you, leading Sheldon to be haunted by Mr. Spock.

The Hawking Excitation

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

The Stag Convergence

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

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 jeop

The Countdown Reflection

The fifth season ends with Howard and Bernadette deciding to get married before his NASA mission, causing the gang to sc

The Date Night Variable

With his friends on dates, Raj must face his loneliness. Also, Wolowitz is caught in an argument between Bernadette and

The Decoupling Fluctuation

When Sheldon learns that Penny is thinking about breaking up with Leonard, he tries to intervene. Meanwhile, in space, t

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 W

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

The Holographic Excitation

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

The Extract Obliteration

Sheldon’s relationship with Stephen Hawking is threatened over a game of “Words with Friends,” and Penny secretly

The Habitation Configuration

Wolowitz struggles with moving out of his mother’s house. Meanwhile, Sheldon is caught in the middle of an argument be

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

The Parking Spot Escalation

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

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.

The Santa Simulation

During a Dungeons and Dragons game, Sheldon revisits Christmas memories; Amy, Penny and Bernadette look for a date for R

The Egg Salad Equivalency

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

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 int

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 expens

The Spoiler Alert Segmentation

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

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" p

The Monster Isolation

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

The Contractual Obligation Implementation

Leonard, Sheldon and Howard give lectures on science to junior high students. The girls ditch work to go to Disneyland.

The Closet Reconfiguration

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

The Tenure Turbulence

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

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 di

The Proton Resurgence

Leonard and Sheldon hire the host (Bob Newhart) of their favorite childhood TV show to perform; Bernadette and Howard ru

The 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 girl

The Bon Voyage Reaction

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

The Hofstadter Insufficiency

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

The Deception Verification

Leonard and Sheldon's friendship is tested; Howard's latest foray into helping his mother has some disastrous side effec

The Scavenger Vortex

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

The Raiders Minimization

Sheldon gets mad at Amy for ruining one of his favorite movies, Raj and Stuart try to make their online dating profiles

The Workplace Proximity

Amy starts working at Caltech which causes friction with Sheldon. Howard agrees with Sheldon who mentions this to Bernad

The Romance Resonance

Sheldon's latest scientific breakthrough leaves him feeling like a fraud; a romantic gesture between Howard and Bernadet

The Proton Displacement

Sheldon seeks payback when Arthur "Professor Proton" Jeffries asks Leonard for help on a project instead of him. Raj get

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-girlfr

The Thanksgiving Decoupling

Sheldon protests when the gang drags him to Mrs. Wolowitz’s house for Thanksgiving. Meanwhile, Penny and Leonard must

The Discovery Dissipation

Leonard has to deal with the fallout of disproving Sheldon's new scientific discovery. Raj spends a week at Howard and B

The 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 th

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

The Occupation Recalibration

Sheldon tries to relax after he is forced to take a vacation. Meanwhile, Leonard struggles to be supportive of Penny aft

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 nigh

The Locomotive Manipulation

Sheldon and Amy take a train ride to Napa Valley with Howard and Bernadette on Valentine's Day. Leonard and Penny take R

The Table Polarization

Leonard buys a dining room table and it causes Sheldon to reevaluate the changes in his life. Meanwhile, Wolowitz is off

The Friendship Turbulence

After arguing with Sheldon, Howard tries to make amends by taking him to NASA headquarters in Houston. Penny has second

The Mommy Observation

When Sheldon visits his Mom in Houston, he is forced to confront a new reality. Meanwhile, Raj’s ‘Murder Mystery’

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

The Relationship Diremption

Sheldon faces a personal crisis after deciding he’s wasting his time with string theory. Meanwhile, a double date betw

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

The Proton Transmogrification

As the gang celebrates Star Wars Day, Sheldon has difficulty dealing with the recent death of Arthur "Professor Proton"

The Gorilla Dissolution

A bad day causes Penny to reevaluate her life choices – including Leonard. Meanwhile, Howard and Bernadette struggle t

The Status Quo Combustion

Sheldon get upset about his career, the destruction of the comic book store and Leonard and Penny's future living arrang

The Locomotion Interruption

Leonard and Amy make an unexpected trip to Arizona to fetch Sheldon; Penny interviews for a job at Bernadette's company;

The 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 s

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

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

The 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

The Expedition Approximation

Sheldon and Raj test whether they could survive a dark-matter research expedition in a salt mine by simulating the condi

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 flirtati

The Prom Equivalency

The girls decide to re-enact their high school proms with the guys. While Sheldon feels under pressure to commit to his

The Septum Deviation

When Leonard gets minor surgery on his nose, Sheldon is the one in need of sympathy. Meanwhile, Raj's parents' impending

The Champagne Reflection

While Sheldon says a tearful goodbye to the final installment of "Fun with Flags", Leonard, Howard and Raj search for so

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 ea

The Space Probe Disintegration

Howard tries to distract Raj, who is anxiously awaiting data from a space probe he helped launch. Meanwhile, Sheldon and

The Anxiety Optimization

When Sheldon becomes stuck in a rut with his work, the gang tries to help him by raising his stress levels. Howard tease

The Troll Manifestation

Leonard and Sheldon publish a paper which is widely accepted except for comments from an internet troll. Meanwhile, the

The Comic Book Store Regeneration

Howard receives some shocking news as everyone prepares for the reopening of Stuart’s comic book store. Penny teaches

The Intimacy Acceleration

As a joke, Sheldon and Penny try an experiment designed to make participants fall in love. Meanwhile, Leonard, Amy, Raj

The 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. Mea

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

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 Bern

The Fortification Implementation

When Sheldon and Amy build a blanket fort, they come to major crossroads in their relationship. Also, Howard meets the h

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

The Graduation Transmission

Howard questions his engineering abilities when he and Sheldon can’t get a toy drone to fly. Meanwhile, a cancelled fl

The Maternal Combustion

The Commitment Determination

As Sheldon presses Leonard and Penny to set a wedding date, he encounters major changes in his own relationship with Amy

The Matrimonial Momentum

After driving to Vegas to get married, Penny struggles with Leonard’s confession that he kissed another girl. Also, Sh

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

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

The 2003 Approximation

Sheldon learns of an impending change in his living arrangements and decides to revert back to 2003, a simpler time befo

The Perspiration Implementation

The guys take a fencing lesson from Barry Kripke and Sheldon finds himself in an awkward position when Kripke expresses

The Helium Insufficiency

In the midst of a nation-wide helium shortage, Sheldon and Leonard take desperate measures to get the supplies they need

The Spock Resonance

Wil Wheaton interviews Sheldon for a Star Trek documentary where he reveals the ring and his plan to propose to Amy. Be

The Mystery Date Observation

Sheldon, Wolowitz and Koothrappali post an online advertisement to find Sheldon a new girlfriend. Also, when Amy is coy

The Platonic Permutation

Sheldon and Amy try hanging out as friends when they spend Thanksgiving together at the aquarium. Also, Wolowitz relucta

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 despi

The Opening Night Excitation

After more than five years of dating, Sheldon and Amy spend their first night together. Also, Leonard, Wolowitz, and Koo

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

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.

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,

The Valentino Submergence

Sheldon and Amy host a live Valentine's Day episode of Fun with Flags, Leonard and Penny grapple with getting older, How

The Positive Negative Reaction

When the gang finds out about Bernadette’s pregnancy, they celebrate by singing karaoke. Also, Bernadette is concerne

The Celebration Experimentation

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

The Application Deterioration

Leonard, Sheldon, and Wolowitz run into problems when they file for a patent for their infinite persistence gyroscope. A

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 Wo

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 Koothrappa

The Viewing Party Combustion

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

The Fermentation Bifurcation

The gang goes to a wine bar and runs into Penny’s old boyfriend, Zack. Also, Bernadette gets stuck spending the evenin

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, Bev

The Convergence Convergence

Chaos ensues when Leonard’s recently divorced parents, Alfred and Beverly, and Sheldon’s devoutly religious mother,

The Conjugal Conjecture

After Sheldon’s mother and Leonard's father share an evening together, everyone deals with an awkward morning the next

The Military Miniaturization

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

The Dependence Transcendence

Tensions rise when the boys struggle to complete their government project on time and Sheldon tries an energy drink to s

The Cohabitation Experimentation

When Amy’s apartment floods, she proposes a “cohabitation experiment” with Sheldon. Also, Howard and Bernadette ar

The Hot Tub Contamination

Leonard and Penny must separate a quarreling Sheldon and Amy when their cohabitation does not go as planned, and Sheldon

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

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

The Brain Bowl Incubation

After a successful experiment combining their genes, Sheldon will stop at nothing to convince Amy they should procreate.

The Geology Elevation

When Bert, a Caltech geologist, wins the MacArthur Genius fellowship, Sheldon is overcome with jealousy. Also, Wolowitz

The Property Division Collision

Sheldon and Leonard try to divvy up their shared belongings, but can’t agree on anything. Also, Koothrappali and Stuar

The Birthday Synchronicity

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

The Holiday Summation

Sheldon and Amy visit Leonard and Penny for the first time since the holidays and share details about their terrible tri

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

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 h

The Locomotion Reverberation

Leonard and Wolowitz try to distract Sheldon when he slows the progress of their guidance system. Also, Penny and Amy ta

The Allowance Evaporation

Sheldon and Amy have their first fight since moving in together, and Koothrappali is shocked at the realities of financi

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 cons

The Escape Hatch Identification

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

The Collaboration Fluctuation

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

The Recollection Dissipation

Sheldon pushes himself to the limit when he collaborates on projects with Leonard and Wolowitz as well as Amy on the sam

The Separation Agitation

Howard and Bernadette have a hard time leaving Halley in day care when Bernadette returns to work. Also, Bert introduces

The Cognition Regeneration

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

The Gyroscopic Collapse

After Leonard, Sheldon and Wolowitz celebrate the completion of the top secret air force project, they are met with an u

The Long Distance Dissonance

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

The Proposal Proposal

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

The Retraction Reaction

Leonard angers the university – and the entire physics community – after he gives an embarrassing interview. Also, A

The Relaxation Integration

Sheldon and Amy struggle with picking a wedding date, which stresses out Sheldon and causes him talking in his sleep. Me

The Explosion Implosion

As Howard worries about fatherhood, he and Sheldon bond when they jointly assemble a model rocket. Meanwhile, Penny bond

The Collaboration Contamination

Sheldon and Raj confide in Bernadette when they can't handle Amy and Howard working together on a science project. Also,

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 o

The Geology Methodology

Sheldon and Bert collaborate on a research project, despite Sheldon’s embarrassment. Also, Penny and Bernadette coach

The Tesla Recoil

Leonard and Howard are furious after they learn Sheldon went to work with the military behind their backs. Also, while B

The Bitcoin Entanglement

Sheldon tries to teach the guys a lesson after they cut him out of a potentially valuable Bitcoin investment. Also, a se

The Confidence Erosion

Sheldon and Amy try to eliminate stress from wedding planning by applying math to the process. Also, Raj “breaks up”

The Celebration Reverberation

Raj and Howard's feud continues as the gang plan Halley's first birthday party. Sheldon's surprise for Amy's birthday go

The Matrimonial Metric

Sheldon and Amy try to pick their Best-Man and Maid of Honor by experimenting on the gang.

The Solo Oscillation

When Sheldon kicks Amy out to work solo, she and Leonard bond during a series of science experiments. Also, Bert the geo

The 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,

The Novelization Correlation

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

The Neonatal Nomenclature

When Bernadette won't go into labor, the gang tries different tactics to get things started. Also, Howard confronts Bern

The Athenaeum Allocation

Leonard jumps through hoops to help secure the perfect wedding venue for Sheldon and Amy. Also, Bernadette and Howard ha

The Gates Excitation

Bill Gates visits Penny's work, and the gang schemes to meet him. Hilarity ensues. Meanwhile, Sheldon is convinced that

The Tenant Disassociation

When Leonard learns Sheldon is the president of the tenants association, he decides to run against him. Also, Bernadette

The Reclusive Potential

A brilliant but reclusive scientist, Doctor Wolcott, invites Sheldon to his cabin in the middle of nowhere, and Leonard,

The Comet Polarization

Sheldon’s comic book store experience changes when writer Neil Gaiman puts Stuart’s store on the map. Also, friendsh

The Monetary Insufficiency

Sheldon goes to Vegas to win money for science. Also, Penny and Bernadette take Amy wedding dress shopping, but her terr

The Sibling Realignment

When Sheldon learns that his mother won’t attend his wedding unless he invites his brother, Georgie, he and Leonard tr

The Bow Tie Asymmetry

When Amy's parents and Sheldon's family arrive, everybody is focused to make sure all wedding arrangements go according

The Conjugal Configuration

Sheldon and Amy's honeymoon runs aground in New York. Penny and Leonard discover they are uncomfortably similar to Amy's

The Wedding Gift Wormhole

Sheldon and Amy drive themselves crazy trying to figure out what 'perfect gift' Leonard and Penny gave them for their we

The Procreation Calculation

The Wolowitzes' life gets complicated when Stuart starts bringing his new girlfriend home. Also, Penny and Leonard talk

The Tam Turbulence

When Sheldon won't tell anyone why he's never mentioned his childhood best friend, Leonard takes matters into his own ha

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 wo

The Imitation Perturbation

When Howard dresses up as Sheldon for Halloween, Sheldon seeks retaliation at Leonard and Penny's Halloween party. Leona

The Grant Allocation Derivation

Leonard is caught between a rock and a hard place when he's responsible for distributing extra grant money. Bernadette t

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

The Citation Negation

Sheldon and Amy are devastated after learning from a Russian paper that Super Asymmetry has already been theorized and d

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

The Paintball Scattering

Penny and Leonard organize a paintball game that results in mayhem when Sheldon is jealous of Amy. Also, Raj catches Anu

The Propagation Proposition

Penny runs into her ex-boyfriend, Zack, who invites her and Leonard to a dinner to meet his newlywed wife. After the din

The Confirmation Polarization

Sheldon and Amy are thrilled when their super asymmetry theory is proven by two physicists, until they try to kick Amy o

The Meteorite Manifestation

Sheldon is thrilled to help Bernadette and Wolowitz navigate bureaucratic paperwork, until he discovers they are breakin

The Donation Oscillation

Penny tries to seduce an abstaining Leonard to ruin his "donation" for her ex-boyfriend, Zack, and his wife, Marissa. Al

The D & D Vortex

The gang finds out Wil Wheaton hosts a celebrity Dungeons and Dragons game involving William Shatner, Joe Manganiello, K

The Conference Valuation

When Penny and Bernadette go to San Diego for a pharmaceutical sales convention, Wolowitz is in charge of the kids. Also

The Laureate Accumulation

When competitors Pemberton and Campbell charm America on a publicity tour, Sheldon and Amy try to bring Nobel laureates

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. A

The Decision Reverberation

Raj is worried people won’t take him seriously in his own field after publishing a paper that suggests he may have dis

The Plagiarism Schism

Kripke has proof that Dr. Pemberton plagiarized his thesis in college, and Sheldon and Amy aren't sure if they should tu

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

The Change Constant / The Stockholm Syndrome

Sheldon and Amy await big news. Meanwhile, Penny and Leonard have some big news of their own. Also, Howard and Bernadett

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 secret