The Big Bang Theory

Pilot

22min - When a pretty girl named Penny moves across the hall, socially awkward scientist Leonard is instantly smitten, much to roommate Sheldon's dismay.

Pilot

The Big Bran Hypothesis

21min - Leonard offers to receive a package on Penny's behalf, but things go awry when Sheldon feels the need to clean her apartment.

The Fuzzy Boots Corollary

22min - Leonard is devastated when he sees Penny kissing another man, and he asks her out on a date under the guise of a group dinner with the guys.

The Luminous Fish Effect

20min - Leonard calls in Sheldon's mother when Sheldon becomes obsessed with weaving ponchos and illuminating fish after being fired from his job.

The Hamburger Postulate

20min - After agreeing to a sexual encounter with Leslie, Leonard becomes upset when he learns she was only interested in him as a one-night stand.

The Middle Earth Paradigm

21min - The guys go well outside their comfort zone when they accept an invitation to Penny's Halloween party, where Leonard has a run-in with Penny's ex.

The Dumpling Paradox

21min - When Penny's friend hooks up with Howard in her apartment, Penny has to crash with the guys ... and becomes the fourth member of their Halo team.

The Grasshopper Experiment

20min - After being set up on a date, shy Raj realizes he's able to talk to women if he's drinking. But he gets too wasted and his date leaves with Sheldon.

The Cooper-Hofstadter Polarization

19min - Leonard and Sheldon are invited to an academic conference to present research they conducted together, but Sheldon doesn't want to participate.

The Loobenfeld Decay

20min - Leonard and Sheldon lie to avoid seeing Penny's bad singing, but Sheldon takes the ruse to unnecessary extremes by inventing a drug-addicted cousin.

The Pancake Batter Anomaly

22min - When germophobe Sheldon gets sick, the guys take off and leave Penny with the task of taking care of the demanding, obnoxious patient.

The Jerusalem Duality

20min - A 15-year-old prodigy pushes Sheldon out of physics research, so he tries to win the Nobel Prize by proposing a replica of Jerusalem in Mexico.

The Bat Jar Conjecture

21min - Sheldon's selfish showboating on the guys' physics bowl team gets him kicked off and replaced by Leslie, leaving him to form his own ragtag team.

The Nerdvana Annihilation

20min - Penny gets mad at the guys when they buy a full-scale model of a time machine, leading Leonard to get rid of all of his collectibles.

The Pork Chop Indeterminacy

21min - Leonard, Howard and Raj all become interested in Sheldon's twin sister, Missy, but Sheldon deems all three of them unsuitable to date her.

The Peanut Reaction

19min - Penny plans a surprise birthday party for Leonard, but things go wrong when Sheldon forgets to buy a present and Howard has a bad reaction to peanuts.

The Tangerine Factor

20min - After Penny has a bad breakup with her boyfriend, she agrees to go on a date with Leonard and both seek advice from Sheldon.