is the 15th episode of the third season of The Big Bang Theory , which originally aired on February 8, 2010. In this Valentine's Day-themed episode, Leonard is invited to visit the Large Hadron Collider in Switzerland and must choose between taking his girlfriend, Penny, or his roommate, Sheldon. Plot Summary
Leonard ultimately travels to Switzerland with Raj , who is thrilled to enjoy the romantic amenities—like champagne and chocolates—originally intended for Penny. Key Characters & Cast [S3E15] The Large Hadron Collision
Sheldon attempts various tactics to change Leonard's mind, including bribery with "Frodo-shaped pancakes," citing roommate clauses, and even presenting a PowerPoint to Penny on why she shouldn't go. is the 15th episode of the third season
"The Big Bang Theory" The Large Hadron Collision (TV ... - IMDb Key Characters & Cast Sheldon attempts various tactics
Leonard is granted a trip to Geneva to see the CERN supercollider. Although Sheldon cites their Roommate Agreement , which requires Leonard to take him if ever invited to CERN, Leonard chooses to take Penny for a romantic Valentine’s getaway.