Penny will consider making a huge career shift while Raj will make an attempt to communicate with extraterrestrial beings in Thursday's all-new episode of "The Big Bang Theory."

Last week, Sheldon and Amy took another step in their relationship when they had their first sleepover after building a blanket fort in his apartment, notes Carter Matt.

In the meantime, Leonard realized that Penny is earning much more money than he is now that she gave up her acting career to become a pharmaceutical sales rep. However, Penny may have a change of heart about her job now that she was offered a role in "Clerks 3.″

In the next episode, "The Communication Deterioration," Penny will have to face the decision of whether or not she should leave her current job to pursue her dreams of being an actress once again, and how this may change the dynamic of her relationship with Leonard.

A preview video also reveals that Penny will discover the pleasure  in repeatedly knocking on Sheldon's door while calling out his name.

"That started off as a joke but you realized there was something strangely enjoyable about it," Sheldon said after opening the door.

"Yeah, I kind of want to do it again," Penny admitted.

"You'll be doing it the rest of your life," Sheldon replied.

According to Carter Matt, the synopsis for the upcoming episode reads as follows:

"When Raj is asked to create a message in case a NASA mission discovers alien life, the guys fight over what he should do. Also, Penny is torn between auditioning for a movie or keeping her successful pharmaceutical sales job."

Season 8, Episode 21 of "The Big Bang Theory," "The Communication Deterioration," will air on Thursday, April 16 on CBS.

Watch a preview below.