Season 4, Episode 24 - The Roommate Transmogrification
Aired May 19, 2011
Bernadette receives her Ph.D., leaving Howard as the only scientist in their group who isn't a doctor. Meanwhile, Raj becomes Sheldon's new roommate after Leonard starts staying with Priya in his apartment and Raj overhears their "Star Trek"-inspired bedroom fantasy.
Season 7, Episode 22 - The Proton Transmogrification
Aired May 1, 2014
Professor Proton delivers Sheldon a lesson in coping with grief when he suffers a loss just as "Star Wars Day" approaches. Meanwhile, a reflective Leonard and Penny get competitive with proposals to change their relationship, and Amy and Bernadette work on a Star Wars-themed gift for the guys' celebration.