The Large Hadron Collision Season 3, Episode 15 -  Aired February 8, 2010

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When Leonard gets the opportunity to visit CERN's Large Hadron Collider in Switzerland on Valentine's Day, he decides to take Penny with him as his guest. Sheldon, of course, believes he should be the one to go on the trip with Leonard and starts a campaign to change his mind.

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Writers: Chuck Lorre (Story), Steven Molaro (Story), Jim Reynolds (Story), Lee Aronsohn (Teleplay), Richard Rosenstock (Teleplay), Maria Ferrari (Teleplay)

Director: Mark Cendrowski

Viewers: 16.26 million Households Rating: 10.3/15 Adults 18-49 Rating: 6/14

Available on iTunes

Episode Notes

  • The title refers to the collision between Leonard and Sheldon about who Sheldon should take with him on his trip to see the Large Hadron Collider in Switzerland.

> Roommate Agreement

Sheldon included a clause in the roommate agreement that, in the event one of them gets the opportunity to visit the CERN Super Collider, requires them to take the other along. The same condition applies should either of them get the chance to go swimming at Bill Gates' house.

Episode Quotes

Leonard: What would you guys do if you were me?
Wolowitz: I would take Sheldon to Switzerland.
Leonard: Seriously?
Wolowitz: Absolutely. And I'd leave him there.

Sheldon: It was you. I touched you!
Penny: Happy Valentine's Day.

Sheldon: Hello.
Penny: Hello.
Sheldon: Ok, enough with the friendly banter. I believe you know why I am here.
Penny: Oh, I always figured it was to study us, discover our weaknesses, and report back to your alien overlords.
Sheldon: Yes amusing. Extraordinary intelligence might well appear extraterrestrial to you, but let me be more specific. I believe you know why I am here in the laundry room.

Penny: I think I caught the flu. *Throwing up*. Or the plague!

Sheldon: There's an economic concept known as a positional good in which an object is only valued by the possessor because it's not possessed by others. The term was coined in 1976 by economist Fred Hirsch to replace the more colloquial, but less precise "neener-neener".


When Leonard announces that the university picked him to go see CERN's Large Hadron Collider in Geneva on Valentine's Day, Sheldon assumes Leonard will be taking him as his guest. After Sheldon runs off to start packing, Leonard tells Howard and Raj that's he's taking Penny.

As Sheldon packs for the trip, Leonard comes and tells him that Penny will be his guest, leaving Sheldon crushed. Leonard assembles some symbols of Switzerland to try reveal the trip to Penny, though eventually he just has to tell her. Penny is excited at the prospect of a ski trip, if not the part about seeing a supercollider. Sheldon points out to Leonard that their roommate agreement stipulates that one roommate must take the other if they have the opportunity to visit the supercollider. Leonard isn't moved by Sheldon's arguments.

On the way to work, Sheldon accused Leonard of being a traitor, while Leonard tries to explain his decision. In the cafeteria, Sheldon turns up and presents Leonard with thirty pieces of silverware, a reference to Judas. The next morning, Sheldon wakes Leonard up by playing the flute and making him Frodo-shaped pancakes. When Leonard won't change his mind about taking Penny, Sheldon takes his breakfast away.

Unable to convince Leonard, Sheldon sets his sights on talking Penny out the trip. He approaches her in the laundry room with a powerpoint presentation on why he should be the one to go to Switzerland. When Penny realizes how much Sheldon wants to go, she feels guilty and promises to talk to Leonard. Sheldon gets to excited that he hugs her. When Penny talks to Leonard, Leonard is angry that Sheldon went behind his back. Leonard declares once and for all that Sheldon will not be going to Switzerland with him, after which Sheldon nullifies the friendship clause of their roommate agreement.

As Penny and Leonard look forward to their trip, Penny starts sneezing. Leonard wakes up in the middle of the night to hear Penny vomiting in the bathroom. When he realizes Penny won't be able to go with him, Leonard goes to tell Sheldon that he can come, but finds him vomiting as well. The day of the trip, Sheldon and Penny are both sick and are eating soup. Sheldon, remembering his hug with Penny, blames her for giving him the flu. Leonard and Raj arrive in Switzerland.