Kaley Cuoco as Penny: An aspiring actress from Omaha, Nebraska. Penny moves in across the hall from Sheldon and Leonard. She waits tables and occasionally tends the bar at the Cheesecake Factory. After giving up hope of becoming a successful actress, Penny becomes a pharmaceutical sales representative. Penny becomes friends with Bernadette and Amy, and they often hang out in each other's apartments. Penny and Leonard form a relationship and eventually marry.
Jim Parsons as Sheldon Cooper: Originally from Galveston, Texas, Sheldon was a child prodigy with an eidetic memory who began college at the age of eleven, and earned a PhD at age sixteen. He is a theoretical physicist researching quantum mechanics and string theory, and despite his IQ of 187, he finds many routine aspects of social situations difficult to grasp. He is determined to have his own way, continually boasts of his intelligence, and has an extremely ritualized way of living. Despite these quirks, he begins a relationship with Amy Farrah Fowler, and they eventually marry.
Sheldon and Amy recruit Leonard to research and write citations for their paper on super asymmetry. While working in the campus library, Leonard and Raj discover a Russian paper that asserts that super asymmetry has no merit. Reluctantly, Leonard shares the news with Sheldon and Amy, who fall into a depressive state and do not leave their apartment. Meanwhile, Bernadette asks Denise to teach her how to play Fortnite: Battle Royale so that she can beat Howard. Despite losing to Howard in a rematch after all of her training, Bernadette revels in beating a disinterested Penny.
They are also fans of Star Wars, Battlestar Galactica, and Doctor Who. In the episode "The Ornithophobia Diffusion", when there is a delay in watching Star Wars on Blu-ray, Howard complains, "If we don't start soon, George Lucas is going to change it again" (referring to Lucas' controversial alterations to the films) and in "The Hot Troll Deviation", Katee Sackhoff of Battlestar Galactica appeared as Howard's fantasy dream girl. The characters have different tastes in franchises with Sheldon praising Firefly but disapproving of Leonard's enjoyment of Babylon 5.[n 1] With regard to fantasy, the four make frequent references to The Lord of the Rings and Harry Potter novels and movies. Additionally, Howard can speak Sindarin, one of the two Elvish languages from The Lord of the Rings.
It's the new "Friends" alright. Not less cheesy, but at times even funnier. I'm from the generation that grew up with "Friends", but I would vote for the millennials. I feel a bit nostalgic for the 1980's sometimes, but I also understand and appreciate the jokes from the "new kids in town". It's pure fun, no more, no less. It has its flaws, but it has its wits too. It's a medicine for foul moods, depression, and loneliness. And as such, I believe it deserves at least 8 out of 10.
Leonard gives an interview on public radio where he admits physics research might be at a dead end. The university is furious and, while trying to think of reasons to put in a retraction, he depresses Sheldon into thinking he might be right. Howard and Raj come over and end up just as depressed. Getting drunk with Penny, the men go to the grave of Richard Feynman and realize there is hope for physics as long as they believe in it. Leonard accidentally sends a drunken email to Human Resources. Meanwhile, Amy and Bernadette agree with each other to keep quiet about the success in their careers so as not to upset Sheldon and Howard. While bragging to each other, they end up arguing which of their fields is better.
Sheldon and Amy's paper is a huge success, but Sheldon is upset when he is not allowed to do interviews, while Amy gets all the attention. Denise asks Stuart to move in with her but he panics and flees. Raj sets up a doorbell camera app for Anu but sees her greet her ex-boyfriend. At a paintball match, all the feuding couples argue, with Raj saying he cannot trust Anu since he does not even know her, throwing the wedding into question. Stuart makes up with Denise by giving her a key to the Wolowitz house. Sheldon tries to do one interview with Amy but leaves when he is asked about the Russian scientists who had earlier disproved their theory.
After Sheldon reminds the guys about the time they mined Bitcoin without him, the guys go on a quest to find their suddenly valuable missing cryptocurrency. They realize the currency is on a laptop which Leonard gave to Penny when they dating, which she then gave to her ex-boyfriend Zack. After Leonard and Penny go to Zack's apartment, he shows them a seven-year-old video that Penny recorded on the laptop soon after she broke up with Leonard. Leonard is touched by the video which shows a drunk Penny lamenting the break-up of her relationship with him.