The Recombination Hypothesis Season 5, Episode 13 -  Aired January 19, 2012

The Recombination Hypothesis

Leonard and Penny might start things up again when Leonard offers Penny a spur of the moment invitation to dinner, on the 100th episode of The Big Bang Theory.

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Guest Stars: Jim Turner as Reverend White

Writers: Chuck Lorre (Story), Bill Prady (Teleplay), Steven Molaro (Teleplay)

Director: Mark Cendrowski

Viewers: 15.83 million Households Rating: 9.3/15 Adults 18-49 Rating: 5.3/15

Available on iTunes

Episode Lists

  • Leonard & Penny: Key Episodes Leonard & Penny: Key Episodes

    The key moments in Leonard and Penny's relationship including the first time they saw each other across the hall, their first kiss, their first date, breaking up and getting back together, the first time Penny says "I love you", a couple of proposals, their engagement, two wedding ceremonies, and finally Penny getting pregnant.

Episode Notes

  • The title refers to Leonard's idea of getting back together with Penny.
  • This is the 100th episode of The Big Bang Theory.

Episode Quotes

Bernadette: Boy, I don't know if I could be friends with Howie if we broke up.
Howard: Why not?
Bernadette: I'm a very vengeful person.
Howard: Really?
Bernadette: With access to weaponized smallpox.

Sheldon: Does anybody have any wood? Oh, come on! I just want wood. Why are you making it so hard?

Sheldon: I know he (Spock) wouldn't care for an outburst of human emotion, but oh goodie, oh goodie, oh goodie!

Sheldon: And now that I have some wood, I'm going to begin the erection of my settlement.

Leonard: Penny, do you have plans for dinner?
Penny: Why, you guys going somewhere?
Leonard: No, just you and me.
Penny: Have you thought this through?
Leonard: Yes, and I think we should go anyway.

News Stories

Title Date Posted
Big Bang Theory tops American Idol in key ratings January 20, 2012

The Big Bang Theory finished ahead of Fox's reality behemoth American Idol in the key 18-49 ratings demographic last night. Idol, now in its eleventh season, dominated the night's ratings, despite significant season-on-season drops in its ratings.  Full story

Episode 5.13 Ratings January 20, 2012

The 100th episode of The Big Bang Theory finished a strong second in the ratings for its time slot and narrowly beat American Idol in the key adults 18-49 demographic.  Full story

CBS Announces Episode 5.13 January 3, 2012

CBS has announced the 100th episode of The Big Bang Theory will air Thursday, January 19th.  Full story


As Sheldon and Leonard climb the stairs to their apartment, Leonard sees Penny's apartment door is open and observes her talking to Amy and Bernadette. Leonard walks over to Penny and asks her if she has plans for dinner tonight, just her and him on a date. Penny accepts Leonard's invitation. Meanwhile, Sheldon opens a package containing a life size Mr. Spock cardboard standee he ordered and is disappointed to find they sent Zachary Quinto instead of Leonard Nimoy.

Amy and Bernadette are with Penny tries on dresses for her date with Leonard. Penny tells the girls they're just going out for dinner and they'll see how it goes, insisting she's not going to make a big deal out of this. Penny admits she's nervous and that her and Leonard are only just now comfortable hanging out with each other again, and she worries the date could wreck that if it goes wrong. Meanwhile, Sheldon, Howard and Raj are playing The Settlers of Catan board game. Sheldon's inability to recognize the sexual innuendo as he describes the game is of great amusement to Raj and Howard. When Leonard gets ready for his date, the guys question why he's going on a date with Penny after the way she broke his heart last time around.

As Leonard and Penny have dinner at a restaurant, they agree to pretend they're actually on a first date to make it less awkward. As they "introduce" themselves, Penny admits she's glad they decided to do this. Leonard jumps the gun and asks if she thinks they're going to get back together. Penny tells him she will always have feelings for him, causing Leonard to point out how the word always makes that sentence worse. Penny says Leonard is over thinking this, like he always does. Penny says everything goes wrong when they talk and admits she once dated a guy for eight months without really talking to him.

Back at the apartment, the guys are still playing the board game. Sheldon continues to miss the double meanings as he describes his moves in the game. Leonard arrives home at eight thirty, leading Howard and Raj to deduce the date did not go well. Later that night, Leonard receives a text from Penny as he tries to sleep. Leonard walks to the apartment front door where Penny is waiting. Penny tells him not to over think this and leads him to her bedroom. After their amorous activities, Penny tells Leonard that she panicked when he started asking where their relationship was going. Penny admits she's worried if they go out, she might do something stupid and dump him again. Leonard has the idea of considering their relationship as like a new version of software, Leonard and Penny 2.0. They test it internally, shake out the bugs, and only roll it out publicly when they're both comfortable with it. They agree to pretend their date went badly to their friends. Penny hands Leonard an inhaler of his that she just remembered she kept.

As Leonard returns to his apartment, Sheldon is just coming out of the bathroom and notices Leonard. Leonard lies and says he needed the bathroom, noticed Sheldon was in there and instead went across the street to the gas station. When Sheldon questions Leonard's story and wonders whether Leonard took his inhaler, Leonard reveals the inhaler Penny just gave him back. Sheldon accepts Leonard's story as plausible, but then questions whether Leonard bought anything from the gas station before using their rest room, as is customary. Sheldon hands Leonard two dollars to go buy some beef jerky.

The gang are having dinner at the Cheesecake Factory. When Howard says he's surprised Leonard showed up after his bad date with Penny, he says they're both grown-ups and can still be friends. Penny comes over to take their orders when Howard slips in a jibe at Leonard and Penny's date. After Penny says sometimes these things just don't work out, Leonard butts in to say they'll always have feelings for each other. Penny is angry that Leonard won't let her always comment go. Penny says the reason they can't be together is Leonard always has to be right, and then excuses herself from waiting on their table.

That evening, Leonard receives another text from Penny, who wants to know why he was such a jerk that night at the restaurant. Leonard says he was just trying to act like they weren't seeing each other, but Penny thinks he was just acting like a tool bag. Leonard walks off to Penny's apartment, claiming sex after fighting is what they do now, and Penny follows. In Penny's bedroom, Leonard wonders why they're bothering with this relationship as every scenario he plays out in his head for them ends badly. Penny again says he's over thinking it.

Back in the apartment hallway, Sheldon interrupts Leonard's day dream to complain about being sent the wrong Mr. Spock. Leonard tells Sheldon that Zachary Quinto was pretty bad ass on Heroes, and then he walks over to Penny's apartment to ask her out on a date. Penny asks Leonard if he's thought this through and he says yes, and he thinks they should do it anyway. Meanwhile, Sheldon is unhappy with his Mr. Spock cardboard cut-out and decides Zachary Quinto is going back. In Penny's apartment, she's preparing for her date with Leonard when she slips into a day dream of her, heaving pregnant, marrying Leonard. Penny remembers to stop by the drug store before their date.