"The Roommate Transmogrification" - Episode 4.24

Leonard and Raj Swap Roommates

The cover for the season 4 DVD of CBS' Big Bang Theory television sitcom. CBS/Chuck Lorre Productions

In the season 4 finale of The Big Bang Theory, the stage is set for unexpected turmoil in relationships and living conditions.


Frustrated by living with his sister Priya and having to overhear her "relations" with Leonard, Raj decides to crash at Leonard's apartment. It works out so well that Raj and Leonard just end up switching apartments, at least until Priya gets her own place.

Meanwhile, Bernadette gets word that her dissertation committee has approved her Ph.D., sending Howard (who only has a Master's degree) into a state of insecurity over his supposedly-dominant role in the relationship, especially after she is offered a high-pay job with a bioresearch company.

Leonard overhears Priya talking to her parents and discovers that she was planning to move back to India without telling him. At the same time, Raj and Penny get drunk and have an unfortunate evening together, ending the episode with a walk-of-shame cliffhanger.


This Episode's Science

Doctorate - The subplot about Bernadette getting her doctorate is of interest. Her doctorate was awarded because she completed independent research, culminating in a dissertation (a research paper, often the length of a short book) which has to be approved by her dissertation committee. Bernadette's doctorate is awarded in microbiology, which is the study of microscopic lifeforms, also called microorganisms. Repeated references throughout the series have suggested that Bernadette's area of expertise involves research on infectious diseases. 

E = mc2 - This equation was discovered by Albert Einstein in 1905, as part of his early work in developing the theory of special relativity.

The equation shows the relationship between energy and mass, which Penny applies in the episode as part of a clever bit of sexual innuendo.


Notable Quotes

Sheldon: I must say, Amy, I was very impressed to see that Bernadette got her PhD.
Amy: It’s indeed admirable. Although, it is microbiology.
Sheldon: Your doctorate is in neurobiology.

I fail to see the distinction.
Amy: I’ll make it simple for you. I study the brain, the organ responsible for Beethoven’s Fifth Symphony. Bernadette studies yeast, the organism responsible for Michelob Lite. Is there something wrong with your neck?


Raj: What’s wrong with me, Penny?
Penny: Nothing, nothing. You know, if we weren’t friends, and you hadn’t brought up that creepy pornography story, I’d be on you like the speed of light squared on matter to make energy.
Raj: Hey, you totally got that right! E equals M C squared.
Penny: I listen. I have no idea what it means, but I listen.