Episode 1 | Pilot

A pair of socially awkward theoretical physicists meet their new neighbor Penny, who is their polar opposite.

Episode 2 | The Big Bran Hypothesis

Penny is furious with Leonard and Sheldon when they sneak into her apartment and clean it while she is sleeping.

Episode 3 | The Fuzzy Boots Corollary

Leonard gets upset when he discovers that Penny is seeing a new guy, so he tries to trick her into going on a date with him.

Episode 4 | The Luminous Fish Effect

Sheldon's mother is called to intervene when he delves into numerous obsessions after being fired for being disrespectful to his new boss.

Episode 5 | The Hamburger Postulate

Leslie seduces Leonard, but afterwards tells him that she is only interested in a one-night stand.

Episode 6 | The Middle Earth Paradigm

The guys are invited to Penny's Halloween party, where Leonard has yet another run-in with Penny's ex-boyfriend Kurt.

Episode 7 | The Dumpling Paradox

When Howard hooks up with Penny's old friend, his absence in the gang causes problems for the rest of the guys.

Episode 8 | The Grasshopper Experiment

When Raj's parents set him up on a blind date, he finds he can talk to women with the aid of alcohol.

Episode 9 | The Cooper-Hofstadter Polarization

Leonard and Sheldon's friendship is put to the test when Leonard wants to present a paper they co-authored at a physics convention, but Sheldon doesn't.

Episode 10 | The Loobenfeld Decay

Leonard lies to Penny so he and Sheldon can get out of watching her perform, but Sheldon believes that the lie has too many loose ends, so he comes up with a new, unnecessarily complex one to replace it.

Episode 11 | The Pancake Batter Anomaly

When Sheldon gets sick, Leonard, Howard and Raj go AWOL, leaving a reluctant Penny to deal with him.

Episode 12 | The Jerusalem Duality

Sheldon decides to give up his work and focus on other tasks when a 15-year-old prodigy joins the university, so the other guys come up with a plan to get rid of him.

Episode 13 | The Bat Jar Conjecture

Sheldon becomes so intent on demonstrating his intellectual superiority over the other guys that they kick him off the Physics Bowl team and replace him with his nemesis, Leslie.

Episode 14 | The Nerdvana Annihilation

Penny gets mad at the guys when their full scale model of a time machine causes her to miss work, which prompts Leonard to give up all of his nerd memorabilia.

Episode 15 | The Pork Chop Indeterminacy

Leonard, Howard and Raj fight over Sheldon's twin sister when she arrives in town. Raj takes part in a drug trial to suppress his selective mutism.

Episode 16 | The Peanut Reaction

When Penny learns that Leonard has never had a birthday party, she and the rest of the guys plan a surprise party for him.

Episode 17 | The Tangerine Factor

After a bad breakup, Penny finally agrees to go out on a date with Leonard, however they both develop doubts and turn to Sheldon for advice.