The Date Night Variable
Raj faces his loneliness when his friends are out on dates; while in space, Wolowitz gets drawn into a fight between Bernadette and his mom.
The Decoupling Fluctuation
Sheldon tries to intervene when he learns that Penny is thinking about breaking up with Leonard; Howard is picked on.
The Higgs Boson Observation
Amy feels threatened by Sheldon's new assistant; Wolowitz starts to feel the pressures of being in space.
The Re-Entry Minimization
Wolowitz's return from space isn't all he expected; game night becomes a gender war.
The Holographic Excitation
The gang heads to Stuart's comic book store to celebrate Halloween; Leonard uses science to seduce Penny.
The Extract Obliteration
A game threatens Sheldon's relationship with Stephen Hawking; Penny secretly signs up for a college class.
The Habitation Configuration
Bernadette wants Wolowitz to move out of his mom's house; Sheldon is caught in the middle of Amy and Wil Wheaton's argument.
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's relationship.
The Parking Spot Escalation
Sheldon and Wolowitz's fight over a parking spot at the university impacts 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 game, Sheldon revisits Christmas memories; Amy, Penny and Bernadette look for a date for Koothrappali.
The Egg Salad Equivalency
When Sheldon is accused of sexual harassment, he ends up getting Raj, Leonard and Wolowitz 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 interpret a comic book.
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 expensive action figures of themselves.
The 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.
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" party at the comic book store.
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 Wolowitz talk to junior high girls about science-related careers; Raj plans a date with Lucy.
The Closet Reconfiguration
Howard considers whether or not he should open a letter from his father; Penny and Leonard host a "grown-up" cocktail party.
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 discovers a secret about Lucy.
The 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.
The Love Spell Potential
Amy and Sheldon's relationship takes a surprising turn during a game of "Dungeons & Dragons"; Lucy and Koothrappali have an awkward date.
The Bon Voyage Reaction
When Leonard is considered for an exciting research opportunity, Sheldon becomes jealous and tries to scare him into backing out. Meanwhile, Raj's relationship with Lucy is strained when he tries to get her to meet his friends.