<P> It turns out that Leonard was imagining everything, and he is still with Sheldon complaining about the Spock cardboard cut - out . Leonard decides that, despite the fact it seems that the relationship will once again end badly, he still wishes to ask Penny out . Penny asks whether he has thought things through . Leonard replies that he has and still thinks they should go ahead with it . Penny therefore agrees and then smiles . </P> <P> In Penny's bedroom, she is again choosing an outfit for her date . Daydreaming she sees herself in a wedding dress and heavily pregnant . Penny rubs her belly and tells Leonard that it is too late to start saying no now . Penny wakes up, apologizes and the dream reminds her to go to the drugstore . </P> <P> "The Recombination Hypothesis" is first episode of a two episode arc featuring Leonard and Penny attempting to restart their relationship that has been one of the major plot lines and driving forces of the series . The arc concludes with the next episode "The Beta Test Initiation" where Penny and Leonard return from their date . The first scene is a salute to the original pilot where Leonard and Sheldon climb the stairs wearing similar outfits and they spot Penny through her apartment door wearing the same shirt from the pilot . Sheldon is disappointed to discover that a Mr. Spock cardboard stand - up he ordered is a portrayal of Zachary Quinto's Spock not Leonard Nimoy's Spock . According to Bill Prady, the co-creator of The Big Bang Theory, approval from Paramount, J.J. Abrams (producer of the new Star Trek series) and Zachary Quinto was required in order to mock Spock . Also, this is the first time that an entire episode is a "dream - sequence", a unique style of storytelling, and is the second Chuck Lorre show to achieve the "dream - sequence" story, after Two and a Half Men in the episode "Frodo's Headshots". </P> <P> "The Recombination Hypothesis" was originally broadcast on January 19, 2012 in the United States between 8: 00 p.m. and 8: 30 p.m. Upon airing, "The Recombination Hypothesis" garnered 15.71 million viewers with the best ever ratings in the adults 25 - 54, adults 18 - 49 and adults 18 - 34 categories . </P>

When do penny and leonard first get together