5 seasons available
The weight of winning a Nobel Prize weighs heavy on Amy's shoulders; Koothrappali and Wolowitz try to relive the good old days after Wolowitz buys a scooter that looks like the one he had years ago.
Koothrappali is worried people won't take him seriously in his own field after publishing a paper that suggests he may have discovered alien life; Leonard wants to be the principal investigator on a plasma physics study.
Kripke has proof that Dr. Pemberton plagiarized his thesis in college, and Sheldon and Amy aren't sure if they should turn him in or not; Wolowitz learns that Bernadette wasn't the only waitress at the Cheesecake Factory who had a crush on him.
Leonard is pleasantly surprised when Beverly comes to visit, and she's genuinely kind to him, until he finds out the real reason she's there; Denise and Stuart overstay their welcome at the Wolowitz house.
Sheldon and Amy await big news.
Bernadette and Wolowitz leave their kids for the first time; Penny and Leonard try to keep a secret; Sheldon and Amy stick together; Koothrappali makes a new friend; the gang travels together into an uncharted future.
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.
Sheldon finds himself competing with the gang for his mother's (Laurie Metcalf) attention when she visits.
An attractive comic book artist tests Leonard and Priya's relationship; Sheldon tries to scare his friends.
Amy is devastated when Penny and Bernadette shop for wedding dresses without her.
Leonard and Penny spend time alone; Sheldon tries to face his fear of birds.
Sheldon is jealous when Stuart (Kevin Sussman), a guy from the comic book store, asks Amy out on a date.
Leonard must face the bully who targeted him in high school; Penny confronts her past actions.
Amy is upset with Sheldon when he isn't impressed with her recent accomplishment; Howard struggles with Bernadette's aversion to children.
Everything could change when Leonard spontaneously invites Penny to a romantic dinner.
Penny and Leonard experiment with their new relationship; Raj forms a bond with his phone's virtual assistant.
Leonard starts to reconsider his friendship with Sheldon; Wolowitz tries to choose his astronaut nickname.
Sheldon goes to work with Amy in her neurobiology lab when the university forces him to take a vacation; Bernadette asks Howard to sign a prenup.
Sheldon and his nemesis, Kripke, compete for a corner office; Penny feels uncomfortable after receiving a gift from Amy.
Sheldon's routine is turned upside down when his barber gets sick; Wolowitz questions his decision to go into space.
Sheldon chooses to participate in a guys-only weekend Star Wars gaming marathon rather than go with Amy to her aunt's birthday party; he gets a lesson from Penny and Amy.
When Penny buys Leonard and Sheldon "Star Trek" collectibles, Sheldon finds himself haunted by Mr. Spock; after a blind date, Raj believes he has met his future wife.
When Stephen Hawking comes to lecture at the university for a week, Wolowitz is given the task of maintaining his wheelchair, making Sheldon green with envy.
Knowledge of Howard's sexual history makes Bernadette reconsider their future together.
Wedding plans are jeopardized when NASA reschedules Howard's mission; Leonard says something in the bedroom that surprises Penny.
The gang tries to help Wolowitz and Bernadette get married before the space launch.
After being humiliated on the radio, Sheldon vows to destroy Kripke; Wolowitz tries not to ruin his new relationship with Bernadette.
Sheldon tries to help Penny understand Leonard's work; Wolowitz gets jealous when Leonard starts hanging out with his new girlfriend.
Leonard is horrified when his mother (Christine Baranski) visits.
Sheldon and Koothrappali attend a university mixer; Leonard discovers that Penny believes in psychics.
After their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.
Sheldon tries to figure out the answer to a physics problem by working with Penny.
Leonard must choose who to bring with him when he goes to see the Large Hadron Collider on Valentine's Day.
Sheldon ends up in traffic court after getting a ticket because of Penny.
Leonard is happy to meet new neighbor Penny, but his roommate thinks he is chasing an impossible dream.