When Bert, a Caltech geologist, wins the MacArthur Genius fellowship, Sheldon is overcome with jealousy. Also, Wolowitz finds an old remote control Stephen Hawking action figure he invented.

After more than nine years together, the gang finally celebrates Sheldon’s birthday, surprising him with a special guest.

Sheldon and Amy host a live Valentine’s Day episode of Fun with Flags, Leonard and Penny grapple with getting older, Howard and Bernadette find a surprise in their hot tub…

In the midst of a nation-wide helium shortage, Sheldon and Leonard take desperate measures to get the supplies they need. Also, Penny and Bernadette download a dating app on Amy’s…

The guys take a fencing lesson from Barry Kripke and Sheldon finds himself in an awkward position when Kripke expresses interest in Amy. Also, when Stuart struggles to get female…

Wolowitz receives some shocking news as everyone prepares for the reopening of Stuart’s comic book store. Penny teaches Sheldon how to “let it go,” but can’t follow her own advice…

While Sheldon says a tearful goodbye to the final installment of “Fun with Flags”, Leonard, Howard and Raj search for something significant in a dead professor’s research. And Bernadette is…

Sheldon faces a personal crisis after deciding he’s wasting his time with string theory. Meanwhile, a double date between Raj, Emily and the Wolowitzes ends in embarrassment for Howard.

Leonard and Amy help Sheldon cope with the shame he’s feeling after his accidental contribution to science is disproved. Meanwhile, Raj must stay with Howard and Bernadette for a week.

The girls get involved when Leonard, Sheldon and Raj compete for tenure at the University.

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.

After the guys throw Howard a bachelor party, Bernadette reconsiders marrying him after learning about his sexual history.

Penny is horrified when Amy gives her a gift: a huge, quite horrible painting of the two of them. With no good way to avoid displaying it, she only hangs…

Leonard and Penny deal with the idea of starting a relationship again and Raj finally finds a “woman” he can talk to without being drunk, in the form of Siri…

Sheldon becomes concerned when everybody begins to hang out at Raj’s apartment and discovers Leonard is the center of the group.

After he’s humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.

When Sheldon learns the guys tampered with his expedition data he got from the arctic, he leaves to Texas in disgrace. This results in the guys following him, which threatens…

Sheldon creates a scientific procedure for making friends.

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.

It’s Halloween night, a busy time of the year for any police precinct. Amy detests the holiday, and is not thrilled when she has to don a costume to go…