The Big Bang Theory Episode Guide

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Episode Guide

The Big Bang Theory: Season 3 (2009)

The Big Bang Theory: Season 2 (2008 - 2009)

  • Season 2 Episode 23: Monopolar Expedition

    Sheldon wins a grant to pay for a summer expedition to the North Pole, and invites his friends to join him. However, the gang's imminent departure causes Leonard and Penny to reconsider their feelings for each other. Johnny Galecki and Kaley Cuoco star

  • Season 2 Episode 22: The Classified Materials Turbulence

    Stuart takes Penny out for a second date, where she drunkenly reveals her true feelings. Meanwhile, Wolowitz uncovers a flaw in the toilet he designed for a Nasa space shuttle, and enlists the aid of his friends to correct it before the craft is launched. Kaley Cuoco, Kevin Sussman and Simon Helberg star

  • Season 2 Episode 21: The Vegas Renormalization

    Sheldon is forced to spend the night at Penny's flat after accidentally locking himself out of his own apartment. Meanwhile, Leonard and Koothrappali take a heartbroken Wolowitz to Las Vegas to cheer him up, where they pay a prostitute to take an interest in their down-hearted friend. With guest star Jodi Lynn O'Keefe

  • Season 2 Episode 20: The Hofstadter Isotope

    Penny catches the eye of a comic-book shop keeper, and Leonard is devastated when she gives serious consideration to dating her new admirer. Desperate for help, Leonard enlists Sheldon to discredit his love rival by preying on his obsessive enthusiasm for Batman. Johnny Galecki, Kaley Cuoco and Kevin Sussman star

  • Season 2 Episode 19: The Dead Hooker Juxtaposition

    Penny feels threatened when another sexy woman moves into the apartment building, but is angered when she senses the men are being manipulated. Comedy, starring Kaley Cuoco, Johnny Galecki and Simon Helberg

  • Season 2 Episode 18: The Work Song Nanocluster

    Sheldon takes charge of Penny's hair accessories business, but complications arise when he becomes over-enthusiastic. Comedy, starring Jim Parsons and Kaley Cuoco

    Friday 11th December 8:30pm EST - KTVT (CBS)
  • Season 2 Episode 17: The Terminator Decoupling

    While travelling to San Francisco, Leonard, Sheldon, Wolowitz and Raj discover actor Summer Glau is sharing a train with them. Desperate to discuss the Terminator TV series with her, the friends devise a series of plans to engage her in conversation. With Johnny Galecki, Simon Helberg, Jim Parsons and Rajesh Nayyar

  • Season 2 Episode 16: The Cushion Saturation

    Tensions between Sheldon and Penny reach an all-time high after a paintballing accident leaves an ugly stain on the awkward physicist's favourite couch cushion. Meanwhile, romance blossoms between Leslie and Howard. Jim Parsons and Kaley Cuoco star

  • Season 2 Episode 15: The Maternal Capacitance

    Leonard and Penny share an intimate moment as they recover from receiving a psychological deconstruction from the physicist's emotially distant mother, an expert in psychiatry and neural sciences. Guest starring Mamma Mia! actor Christine Baranski

  • Season 2 Episode 14: The Financial Permeability

    Penny runs into money troubles, so Sheldon offers to lend her some cash to help her pay the rent. However, when Leonard discovers that his neighbour's former boyfriend Kurt is the cause of her financial woes, he gathers the gang for a confrontation. Starring Jim Parsons, Johnny Galecki and Kaley Cuoco

  • Season 2 Episode 13: The Friendship Algorithm

    Sheldon decides to put his formidable brain power to use in formulating a scientific procedure for making friends. However, to prove his findings, the usually snide physicist must first befriend a fellow scientist to gain the use of his powerful computer. Starring Jim Parsons and John Ross Bowie

  • Season 2 Episode 12: The Killer Robot Instability

    Sheldon and the gang are excited when Barry Kripke challenges them to a robot duel and they cannot wait to start building their 'killer' machine called Monte. Meanwhile, Penny confronts Wolowitz about his crude behaviour toward women. Guest starring John Ross Bowie

  • Season 2 Episode 11: The Bath Item Gift Hypothesis

    Sheldon's obsession with gift-giving etiquette annoys his friends as Christmas approaches. Meanwhile, Leonard is thrilled to meet an award-winning scientist, only to be filled with jealously when his new colleague takes an interest in Penny. With guest star Michael Trucco

  • Season 2 Episode 10: The Vartabedian Conundrum

    Leonard turns to Penny for much-needed advice when his relationship with Stephanie takes off faster than he would have liked. Comedy, starring Johnny Galecki and Kaley Cuoco

  • Season 2 Episode 9: The White Asparagus Triangulation

    Sheldon is delighted that Leonard has finally managed to find a girlfriend matching his high standards, but his over-exuberance looks set to cause problems. Jim Parsons and Johnny Galecki star

  • Season 2 Episode 8: The Lizard-Spock Expansion

    A smitten Wolowitz becomes convinced he has met his soul-mate in the form of Stephanie Barnett, a distinguished resident surgeon. However, he fails to realise that the object of his affections is far more interested in Leonard. Less Than Perfect's Sara Rue guest stars

  • Season 2 Episode 7: The Panty Pinata Polarization

    Penny begins visiting the boys' flat to watch her favourite shows after her TV breaks down. However, when Sheldon tires of her presence he bans her from his home, only for her to seek an embarrassing form of vengeance. Meanwhile, Howard and Raj search for the America's Next Top Model house

  • Season 2 Episode 6: The Cooper-Nowitzki Theorem

    An obsessive student takes a shine to Sheldon, and before he knows what has happened, the misanthropic physicist finds himself with a girlfriend. However, his new partner quickly expresses distaste toward his social life, and removes him from his limited circle of friends by forcing him to work on a troublesome scientific problem. With guest star Riki Lindhome

  • Season 2 Episode 5: The Euclid Alternative

    Sheldon is forced to confront his fear of driving when both Penny and Howard refuse to give him a lift to work. Desperate to be free of the obligation, Leonard and the gang stage an intervention to discover why the physicist never learned to drive. Jim Parsons stars

  • Season 2 Episode 4: The Griffin Equivalency

    Leonard encourages Howard and Sheldon to be supportive when Raj is named one of People magazine's '30 to Watch Under 30'. However, when Raj makes a move on Penny, Leonard struggles to maintain a positive perspective on his friend's new-found confidence. Kunal Nayyar and Kaley Cuoco star, with a guest appearance by Charlie Sheen

  • Season 2 Episode 3: The Barbarian Sublimation

    Penny becomes addicted to an online game based on the world of Conan the Barbarian. As her obsession intensifies, she begins to neglect her friends, instead seeking the company of the usually snide Sheldon and continually pestering him for advice. Kaley Cuoco and Jim Parsons star

  • Season 2 Episode 2: The Codpiece Topology

    Leonard is crushed when he sees Penny with another man, and decides to cut his losses by going back to Leslie Winkle - something Sheldon is not at all happy with. Johnny Galecki, Kaley Cuoco and Jim Parsons star

  • Season 2 Episode 1: The Bad Fish Paradigm

    Sheldon finds himself forced to keep a secret when Penny decides to confide in him about what happened on her disappointing first date with Leonard. Comedy, starring Johnny Galecki, Kaley Cuoco and Jim Parsons

The Big Bang Theory: Season 1 (2007 - 2008)

  • Season 1 Episode 17: The Tangerine Factor

    Following the break-up of Penny's relationship, Leonard finally summons up the courage to ask her out. When she accepts, each of them separately asks Sheldon for advice on how to handle the forthcoming date. Last in series, starring Johnny Galecki, Kaley Cuoco and Jim Parsons

  • Season 1 Episode 16: The Peanut Reaction

    When Penny finds out Leonard's family never celebrated his birthdays she enlists Sheldon's help to organise him a surprise party, while Wolowitz gets him out of the way by staging an emergency hospital visit. Kaley Cuoco and Johnny Galecki star

  • Season 1 Episode 15: The Pork Chop Indeterminacy

    Sheldon's twin sister visits, and captures the hearts of all his friends. Leonard is confident he can win her over, until her brother declares that he will have the final say on who can date her

  • Season 1 Episode 14: The Nerdvana Annihilation

    When Penny makes fun of Leonard's habit of collecting tacky memorabilia, he decides to give it up - but his friends object and do everything possible to persuade him to return to his geeky ways

  • Season 1 Episode 13: The Bat Jar Conjecture

    The gang kick Sheldon out of their bowling team, so he decides to prove his superiority by forming a rival squad of his own. Johnny Galecki, Jim Parsons and Kaley Cuoco star

  • Season 1 Episode 12: The Jerusalem Duality

    Sheldon feels threatened when he meets a 15-year-old physics prodigy who is even smarter than he is, so Leonard agrees to help him discredit the precocious youngster's research. Johnny Galecki, Simon Helberg and Kaley Cuoco star

  • Season 1 Episode 11: The Pancake Batter Anomaly

    When Sheldon falls ill his friends decide to keep their distance, knowing he will be in a terrible mood, but an unsuspecting Penny offers to nurse him. Johnny Galecki, Simon Helberg and Kaley Cuoco star

  • Season 1 Episode 10: The Loobenfeld Decay

    Sheldon and Leonard invent excuses to avoid having to attend Penny's performance in a production of the stage musical Rent, but maintaining the pretence becomes increasingly complicated. Johnny Galecki, Simon Helberg and Kaley Cuoco star

  • Season 1 Episode 9: The Cooper-Hofstader Polarization

    Leonard and Sheldon receive an invitation to present their research to a physics conference, but Sheldon's reluctance to pander to his peers causes conflict between the friends - with Penny's intervention only making matters worse. Johnny Galecki and Jim Parsons star

  • Season 1 Episode 8: The Grasshopper Experiment

    Raj's parents set him up on a blind date with the hope of initiating an arranged marriage but although he discovers he can talk to her, she seems more interested in Sheldon. Meanwhile, Penny starts her new job as a bartender. Kunal Nayyar and Jim Parsons star

  • Season 1 Episode 7: The Dumpling Paradox

    When Wolowitz hooks up with one of Penny's promiscuous friends, the guys fly into a state of panic and enlist their neighbour to make up the numbers in their game of Halo. Simon Helberg, Kaley Cuoco and Johnny Galecki star

  • Season 1 Episode 6: The Middle Earth Paradigm

    Penny hosts a Hallowe'en party, which proves to be a worthy test for Leonard, Sheldon, Wolowitz and Koothrappali's social skills. Kaley Cuoco, Johnny Galecki and Simon Helberg star

  • Season 1 Episode 5: The Hamburger Postulate

    Leonard worries he may be wasting his time with Penny, so he ends up forging a connection with Leslie. Meanwhile, Sheldon frets over a variation to his hamburger routine. Johnny Galecki, Kaley Cuoco and Jim Parsons star

  • Season 1 Episode 4: The Luminous Fish Effect

    When Sheldon loses his job, he explores new activities in a bid to find a purpose in life other than physics, but Leonard takes drastic action to restore his friend to his old self. Laurie Metcalf guest stars

  • Season 1 Episode 3: The Fuzzy Boots Corollary

    Leonard is upset to learn Penny is dating someone, so his friends and fellow scientists persuade him he should find a romance of his own by asking another woman out. Johnny Galecki and Kaley Cuoco star

  • Season 1 Episode 2: The Big Bran Hypothesis

    Leonard enlists his room-mate's help when he agrees to drop off a parcel for new neighbour Penny, but when Sheldon sees how messy her room is, he attempts to do a good deed which is not well received. Johnny Galecki, Jim Parsons and Kaley Cuoco star

  • Season 1 Episode 1: Pilot

    Comedy about two friends who understand more about the laws of physics than they do about interacting with other people. When a free-spirited beauty called Penny moves in next door, Leonard is immediately smitten with her, but Sheldon warns him he runs the risk of a broken heart if he tries to romance her. Johnny Galecki, Simon Helberg and Kaley Cuoco star

The Big Bang Theory: