The Big Bang Theory


'The Big Bang Theory' Season 4 Episodes

The Big Bang Theory - Season 4

The Big Bang Theory - Season 4

Leonard and Sheldon are brilliant physicists. But none of that genius helps them interact with people, especially women. All this begins to change when a free-spirited beauty named Penny moves in next door.

The Big Bang Theory S4E1
Episode 1  •  September 23rd, 2010

The Robotic Manipulation

Sheldon has been communicating with Amy Farrah Fowler for the past few months via text messages. Penny convinces Sheldon he should go on a date with her after he informs the group that he and Amy are going to procreate. Penny learns that this is Sheldon's first date EVER. Sheldon gets Penny to drive him and Amy around on their date. Penny tries repeatedly to break the awkward silence with no luck until she points out to Amy that this is Sheldon's first date. Sheldon and Amy discuss the topic and then Sheldon points out the rather large number of men that have come in and out of Penny's life.

Wolowitz creates a robotic hand which he shows off to the guys. While Wolowitz tests out different commands on the robot he realizes that the hand has a very realistic feel. Wolowitz gets into a very compromising position when the robot hand freezes up on a very personal area. Leonard and Koothrappali must take him to the hospital since neither are willing to volunteer to help Wolowitz free himself from the robots grip.

The Big Bang Theory S4E2
Episode 2  •  September 30th, 2010

The Cruciferous Vegetable Amplification

Determined to live long enough for the moment when man and machine become one, Sheldon decides he must cease all physical contact with the outside world. Using a computer screen and basic robot technology, he winds up alienating the entire gang in the process. Sheldon wants to avoid his friends due to his consuming too many gas producing vegatables. So he creates a computer screen version of himself that has wheels and is controlled by robotics. He winds up joining that gang at the Cheescake Factory where they see the one and only Steve Wozniak sitting near by. Shelbot approaches him, and Wozniak compliments his machine.

The Big Bang Theory S4E3
Episode 3  •  October 7th, 2010

The Zazzy Substitution

After having a major disagreement about whose work is more important, Sheldon and Amy Farrah Fowler decide to end their relationship. As a means of coping, Sheldon begins to acquire cats for companionship. When the number of cats reaches 25, Leonard steps in and brings in the big guns – Sheldon’s mother. Lauri Metcalf guest stars again as Sheldon's mother, Mary. She flies in from Texas to help Sheldon get out of his funk over Amy. She calls a meeting, inviting Amy, where she points out that Amy is all worng for Sheldon. Sheldon automatically rejects his mother's opinion, and suggests to Amy that they restart their relationship. Amy agrees, and Shedlon's mother has won by using reverse psychology.

The Big Bang Theory S4E4
Episode 4  •  October 14th, 2010

The Hot Troll Deviation

While the gang has dinner at the Cheesecake Factory one evening, Wolowitz sees Bernadette, who he hasn't spoken to since they broke up. He realizes how much he misses her and wants to get back together with her, when his fantasy girl Katee Sackhoff can't even keep his interest. He enlists Penny's help to get Bernadette back but she insists that Wolowitz tell her the reason they broke up in the first place - something he has never spoken about.

Meanwhile, Sheldon and Koothrapali deal with working together in the same office space. When Sheldon doesn't want to buy Raj his own desk for the office, Raj convinces Sheldon to let him buy one himself. He buys such an enormous desk and gets a rise out of Sheldon which leads to a battle of wills.

The Big Bang Theory S4E5
Episode 5  •  October 21st, 2010

The Desperation Emanation

Amy Farrah Fowler tells Sheldon that she wants to introduce him to her mother. Sheldon freaks out, thinking that Amy wants to take their relationship to the next level while he is completely fine with the level they're currently at. He proceeds to go out of his way to avoid her and even takes the address numbers off their building in hopes of confusing and thwarting her. In the end, she gets to him and explains that she simply wants to introduce him to her mother as her boyfriend so her mother will get off her back once and for all. She doesn't want to change a thing about their relationship. Sheldon, intrigued by the ruse they're going to play, happily agrees.

Meanwhile, Leonard is depressed that everyone seems to be paired off except for him. He invokes the girlfriend pact with Wolowitz which requires the girlfriend of one of the guys to set up one of the other guys with her friends. Bernadette brings her friend Joy to a double date with her, Howard and Leonard. Unfortunately, Joy isn't quite who Leonard had in mind and the date ends up being one of his worst.

The Big Bang Theory S4E6
Episode 6  •  October 28th, 2010

The Irish Pub Formulation

Koothrappali’s sister, Priya, comes for a visit and we find out she and Leonard have a romantic past unbeknownst to the rest of the guys because Leonard and Howard made a pact to never make a move on her. When Sheldon discovers Leonard sneaking Priya out of the apartment the next morning, Leonard bribes him with the promise of having a train day if Sheldon will keep the secret. Sheldon agrees but is terrible at keeping secrets so he instead comes up with an elaborate story of how Leonard met an Irish bartendar at Pasadena's best Irish pub. Leonard tells Sheldon that the story isn't necessary and that if he just keeps his mouth shut, everything will be okay.

When the guys gather the next day, after Koothrappli has taken Priya to the airport, Leonard feels so guilty about what he did that he immediately starts telling the story that Sheldon concoted for him. The truth comes out and both Raj and Howard feel betrayed. This starts an argument with all of them which in turn reveals secrets they've all been keeping from each other.

The Big Bang Theory S4E7
Episode 7  •  November 4th, 2010

The Apology Insufficiency

Leonard is still depressed about being alone but thinks his problem with women stems from the fact that he lacks confidence. He vows that the next time he meets a woman who he thinks is attractive, he will stand up full of self-assurance. Meanwhile Wolowitz is being considered for the team for the new Defense Department surveillance satellite. Because it's top secret, he tells the guys that the FBI might be calling them to ask questions about Howard. Koothrapali is hesitant about talking to the FBI as he fears they might deport him, even though he's in the country legally. When an attractive female FBI agent arrives at his door, he has to think fast about how he's going to talk to her because he realizes he has no alcohol in the house. Thankfully he finds a rum cake in the fridge. The agent then shows up at Leonard's lab to ask questions about Howard and he takes advantage of the situation, exudes his confidence and asks her out. Lastly, the agent speaks with Sheldon who has no interest in talking about Howard but accidentally tells her how he crashed the Mars Rover while attempting to impress a woman. When the Defense Department takes Howard off the team, Sheldon feels so guilty that, as an apology, he gives Howard his seat on the couch. Howard accepts the apology and the seat, but when the gang gathers at Leonard's and Sheldon's, Sheldon can't stand the new arrangment and takes his seat back.

The Big Bang Theory S4E8
Episode 8  •  November 11th, 2010

The 21-second Excitation

The guys are very excited about going to a screening of Indiana Jones and Raiders of the Lost Ark because there are 21 seconds of additional footage being seen for the first time. When they arrive to wait in line, they're concerned about how far back in line they are and how they might not get inside. Sheldon blames the other three for various reasons as to why they didn't get there sooner. Wil Wheaton shows up and taunts the guys. He and his friends are treated like VIPs and bypass the entire line to get seats inside. When they finally let everyone in, the guys miss getting into the screening by two people and Sheldon is convinced that it's because of Wil Wheaton. Resolved that if he doesn't get to see the movie neither does Wil Wheaton, Sheldon steals the film reels and runs with the angry audience chasing after him and the other guys.

Meanwhile, Penny, Bernadette and Amy have a girls' night. They play truth or dare and Amy asks Penny that if she and Leonard are no longer dating, why does she continue to spend so much time with him? She also wants the truthful answer of how Penny would feel if Leonard started seeing another girl. Uncomfortable, Penny goes to her room where Amy tries to comfort her in her strange way.

The Big Bang Theory S4E9
Episode 9  •  November 18th, 2010

The Boyfriend Complexity

When Penny's dad comes to visit, Leonard discovers that she told her parents they were back together because Leonard was always their favorite boyfriend of hers. Leonard takes full advantage and plays his boyfriend role to the hilt to Penny's dismay. Raj is disappointed when Bernadette shows up during his and Howard's quality time but they end up bonding more than Howard would like which forces him to put a stop to it in a very awkward way.

The Big Bang Theory S4E10
Episode 10  •  December 9th, 2010

The Alien Parasite Hypothesis

While out at dinner with Penny and Bernadette, Amy Farrah Fowler meets Zack, Penny's ex-boyfriend. Much to her surprise, she finds herself flushed with an elevated heart rate and a tingling sensation. She and Sheldon discuss her symptons and she discovers that she was sexually aroused. Uncertain of what to do, Sheldon asks Penny for advice and convinces him that indeed there is something Sheldon can do for a horny Amy Farrah Fowler. He accompanies Amy to a bar where she propositions Zack but when Zack is utterly confused by the language she uses, Amy decides to abandon her assignment. When Zack shakes her hand to say goodbye, she gets what she needed and tells Sheldon she can move on.

Meanwhile, Howard and Raj argue over who would be the superhero and who would be the sidekick between the two of them. Much to Leonard's annoyance, they decide to settle the matter with a wrestling match that seems to go on forever since neither one will make the first move.

The Big Bang Theory S4E11
Episode 11  •  December 16th, 2010

The Justice League Recombination

Penny is dating Zack again and becomes upset when the guys make fun of him, making him feel stupid. When they go over to Penny's to apologize to him, they realize he can help them out with the New Year's costume competition at the comic book store and offer to make him Superman in their Justice League. Unhappy that he's been usurped, Leonard calls dibs on being The Green Lantern which forces Koothrappali, much to his dismay, to dress up as Aquaman. Zack signs Penny up to be Wonder Woman but she refuses to wear the dark wig. When Zack sides with the guys that she should wear it, she gets upset and tells the guys she's not going to the party at all. After failed attempts by Zack and Sheldon, Leonard goes over to Penny's to try and make amends and get her to come with them. They share a nice moment and at the party, the gang ends up winning the costume contest.

The Big Bang Theory S4E12
Episode 12  •  January 6th, 2011

The Bus Pants Utilization

Leonard comes up with a great idea for an phone app and the guys all pitch in to help. When Sheldon becomes too controlling, Leonard fires him. Penny finds Sheldon by himself in the hall, she invites him to work with her on an app of their own. Quickly annoyed with him, Penny begs the guys to take Sheldon back. When they refuse, she convinces Sheldon to practice his sarcasm and apologize to Leonard so he can work with them again.

The Big Bang Theory S4E13
Episode 13  •  January 20th, 2011

The Love Car Displacement

The gang goes on a road trip to Big Sur where the guys, Bernadette and Amy are speaking at a symposium. Penny tags along as Amy's plus one for the free spa weekend that's promised. When Wolowitz meets Bernadette's hulk of an ex-boyfriend, he becomes really insecure and they have a fight, throwing the hotel room arrangements into chaos. Rick Fox guest stars in this on as Bernadette's ex boyfriend.

The Big Bang Theory S4E14
Episode 14  •  February 3rd, 2011

The Thespian Catalyst

Sheldon has agreed to take part in a short lecture series at the university. After completing his first lecture, he is shocked to find out just how much the students hate him as a teacher. Amy tells him that teaching is a performing art and suggests to Sheldon that perhaps her best friend, Penny, could share some of her acting skills with Sheldon to make him a better teacher and learn to connect with his audience better. Sheldon goes to Penny and asks her to give him some acting lessons. Sheldon doesn't take Penny's direction well and is an awful actor yet he thinks he is a brilliant playwright and improvizationalist and decides to use his newfound skills on his students.

Koothrappali is feeling down about not having a girlfriend and Bernadette reasures him that someone as great and cute as him will not stay single for long. Soon Koothrappali realizes he ha as crush on Bernadette and we see several daydreams with he and Bernadette. The final one ending in a Bollywood style musical number.

The Big Bang Theory S4E15
Episode 15  •  February 10th, 2011

The Benefactor Factor

An incredibly wealthy older woman is considering making a huge donation to the school's science program. When she takes a liking to Leonard, Sheldon attempts to pimp Leonard out in the name of science. Jessica Walter guest stars as the older woman that wants Leonard. Josh Molina guest stars as the president of the University. Leonard swears that he will not sleep with her just for the money. But in the end he succumbs to her seduction.

The Big Bang Theory S4E16
Episode 16  •  February 17th, 2011

The Cohabitation Formulation

Wolowitz and Bernadette are in a great spot in their relationship but he never stays over because he always has to run home to help his mom out in the morning. Bernadette wants them to move in together but Wolowitz can't see the two of them living with his mother working out so well. Finally, Bernadette has enough and gives him an ultimatum - her or his mother. Howard chooses Bernadette and shows up at her door all ready to move in. Unfortunately, what Bernadette quickly discovers is that Howard didn't quite leave his mother behind - he just replaced her with Bernadette! He expects her to make him dinner, take him to the dentist and do everything his mother does. When she calls him on it, Howard thinks she's being ridiculous and hightails it back to his mother's.

Meanwhile, Priya, Raj's sister is back in town and reunites with Leonard, even though Raj forbids it. Penny meets Priya, and Amy Farrah-Fowler, as a witness to all of this, offers her shoulder for Penny to cry on as she understands how hard it must be to know Penny's been replaced by a much better and more suitable mate for Leonard. At first, Penny feigns indifference but eventually she breaks down, much to Amy's delight as she can use Penny and continue her study of how intense crying and emotions are triggered in the brain.

The Big Bang Theory S4E17
Episode 17  •  February 24th, 2011

The Toast Derivation

With Leonard dating Priya and Priya staying with her brother, Raj, the gang starts hanging out at Raj's place, much to Sheldon's disbelief. Amy Farrah Fowler helps with him the startling realization that it is Leonard who is the social center of their group and not Sheldon. Undeterred, Sheldon decides to create his own social group at his apartment and invites over Barry Kripke, Zack, Penny's ex, Stuart, the comic book store owner and Levar Burton, from TV's Reading Rainbow. Barry, Zack and Stuart all show up for various reasons of their own but Stuart and Barry soon become enamored with Zack's stories of getting girls and Sheldon quickly abandons them.

Meanwhile, the gang is hanging out a Raj's having chili con carne, laughing about what Sheldon would say if he was there. They soon discover that they actually miss his presence. Sheldon soon shows up, having left his newly formed group and says everything they all thought he would say. This time, though, rather than being annoyed, the gang encourages his criticism.

Amy and Bernadette kidnap Penny for a girls' night out to help her get over Leonard and his new relationship with Priya. Initially Penny is resistant to meeting anyone, but after Amy's incessant prodding, Penny decides that a one night stand may be just the thing for her.

The Big Bang Theory S4E18
Episode 18  •  March 10th, 2011

The Prestidigitation Approximation

Wolowitz drives Sheldon crazy as he tries to figure out Howard's magic trick. It seems to work as Howard does it for Raj and Penny and Sheldon spends the rest of the episode coming up with various ways to successfully do the trick himself but to no avail. In the end, we find out that Raj and Penny are in on the joke and Howard's magic trick is simply just a trick on Sheldon - because it's too fun for them when they drive him nuts.

Meanwhile, Priya tells Leonard that she feels uncomfortable with the amount of time that Penny spends hanging around him. She asks him to talk to Penny to let her know that they can't hang out together. Leonard attempts to tell Penny several times but can't seem to get the words out even though he tells Priya that Penny totally understood about the situation and will stay away from them. He's caught in his lie when Penny sees him and Priya out to dinner and tries to join them to kill time before meeting the rest of the gang out for a movie. In the end, Penny figures out what's going on and ends their friendship for him.

The Big Bang Theory S4E19
Episode 19  •  March 31st, 2011

The Zarnecki Incursion

When someone hacks Sheldon's online gaming account, the guys go on a quest to find the culprit.

The Big Bang Theory S4E20
Episode 20  •  April 7th, 2011

The Herb Garden Germination

Sheldon and Amy experiment on their friends by spreading gossip, while Howard takes a big step in his relationship with Bernadette.

The Big Bang Theory S4E21
Episode 21  •  April 28th, 2011

The Agreement Dissection

Sheldon and Priya knock heads when she uses her lawyer skills to pick apart the roommate agreement. Frustrated, Sheldon goes out and ends up spending a girls' night with Penny, Bernadette and Amy.

The Big Bang Theory S4E22
Episode 22  •  May 5th, 2011

The Wildebeest Implementation

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

The Big Bang Theory S4E23
Episode 23  •  May 12th, 2011

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 Big Bang Theory S4E24
Episode 24  •  May 19th, 2011

The Roommate Transmogrification

After hearing Leonard and Priya indulge in a Star Trek bedroom fantasy, Raj moves in with Sheldon on the fourth season finale.

Top TV Shows