Season 2

Season 2
Episodes – 23
The Bad Fish Paradigm
Penny's first date with Leonard goes awry; Penny finds Sheldon to be an unwilling confidant.
Air Date September 22, 2008
The Codpiece Topology
A jealous Leonard reacts to Penny's new guy by rebounding with Leslie.
Air Date September 29, 2008
The Barbarian Sublimation
Sheldon creates a monster when he introduces Penny to online gaming.
Air Date October 6, 2008
The Griffin Equivalency
Raj gets an inflated ego and makes a play for Penny after being referenced in a magazine article.
Air Date October 13, 2008
The Euclid Alternative
Leonard and his friends stage an intervention to force Sheldon to face his fear of driving.
Air Date October 20, 2008
The Cooper-Nowitzki Theorem
Sheldon and the gang are confused when a young grad student is attracted to him.
Air Date November 3, 2008
The Panty PiƱata Polarization
When Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate.
Air Date November 10, 2008
The Lizard-Spock Expansion
Leonard inadvertently steals away the new woman Wolowitz thinks is the love of his life.
Air Date November 17, 2008
The White Asparagus Triangulation
Sheldon is thrilled when Leonard starts dating a woman who meets Sheldon's stringent standards.
Air Date November 24, 2008
The Vartabedian Conundrum
Leonard asks Penny for advice when his new relationship starts moving too fast.
Air Date December 8, 2008
The Bath Item Gift Hypothesis
Penny starts dating Leonard's handsome colleague; Leonard and his friends are tortured by Sheldon's obsession with gift-giving etiquette.
Air Date December 15, 2008
The Killer Robot Instability
Penny's criticism of Wolowitz's romantic life pushes him into depression and AWOL for a fighting robot battle the rest of guys are depending on him for.
Air Date January 12, 2009
The Friendship Algorithm
Sheldon creates a scientific procedure for making friends.
Air Date January 19, 2009
The Financial Permeability
Sheldon's solution to Penny's financial difficulty leads to a confrontation between Leonard and Penny's ex-boyfriend.
Air Date February 2, 2009
The Maternal Capacitance
Leonard and Penny are drawn together after a disastrous visit from Leonard's mother.
Air Date February 9, 2009
The Cushion Saturation
A paintball game leads to a fight between Sheldon and Penny, and romance for Leslie and Wolowitz.
Air Date March 2, 2009
The Terminator Decoupling
Leonard, Sheldon and Wolowitz are ecstatic to learn that a famous science-fiction actress (Summer Glau) is on board the train they are taking to San Francisco.
Air Date March 9, 2009
The Work Song Nanocluster
Penny's home business turns into a complete nightmare when Sheldon takes over.
Air Date March 16, 2009
The Dead Hooker Juxtaposition
Penny squares off with a new beautiful female neighbor who may become the building's "new Penny."
Air Date March 30, 2009
The Hofstadter Isotope
A fellow comic book enthusiast's hitting on Penny leads to Leonard and Howard going to a bar's Ladies' Night.
Air Date April 13, 2009
The Vegas Renormalization
Leonard and Koothrappali escort a heartbroken Wolowitz to Las Vegas, and Sheldon becomes locked out of his apartment and must stay with Penny.
Air Date April 27, 2009
The Classified Materials Turbulence
Penny's second date with Stuart sees her making a comment that gives Leonard new hope for a relationship with her. Wolowitz realizes there's a crucial error in a NASA project he's working on.
Air Date May 4, 2009
The Monopolar Expedition
The guys' plan to work over the summer at the North Pole makes Penny revaluate her feelings for Leonard.
Air Date May 11, 2009