'The Big Bang Theory' executive producers Chuck Lorre, left, and Steve Hollland and stars Kevin Sussman, Mayim Bialik, Jim Parsons, Kaley Cuoco and Kunal Nayyar stand to the left of 'The Big Bang Theory' stage plaque, with executive producer Bill Prady, star Melissa Rauch, executive producer Steven Molaro and star Johnny Galecki, director Mark Cendrowski and star Simon Helberg on the right. (Photo: Warner Bros.)
Professor Proton, Sheldon's favorite childhood show, is being rebooted. After unsuccessfully auditioning for the part, he goes to Wil Wheaton for acting tips for his second audition. However, Sheldon is later dismayed when Wil is offered the role instead. Talking it over with Arthur in his dreams, he is still upset to see his idol replaced and considers Wil an enemy again. Meanwhile, Howard gets a vasectomy while Bernadette is on bed rest. Penny offers to take care of Halley for them, but they insult her by expecting her to be irresponsible. Halley ends up saying her first word by calling Penny "Mama."
The episode opens with a short montage of clips from the series' twelve seasons, then segues to Sheldon and Amy, who are up late waiting for a call from the Nobel Committee. Following a prank call from Kripke, they are told they've won the Nobel Prize in Physics for their super-asymmetry work. The attention from the media and the university bothers Sheldon. Amy is saddened by an unflattering picture of her in a news report, so Raj convinces her to get a makeover. She loves her new look but Sheldon demands she change it back. Leonard calls him out for being rude, but Sheldon flees when he sees Penny emerge from the newly repaired elevator. Sheldon and Penny go to the Cheesecake Factory and Penny tells Sheldon that change is the only constant thing in life. On a TV, they see Bernadette and Howard take credit as Sheldon and Amy's best friends. Raj and Leonard defend Amy, with Leonard accidentally breaking Sheldon's DNA molecule model in Apartment 4A. Penny convinces Sheldon to ride in the elevator.
And while the actor, 44, doesn't have any other gigs lined up just yet—his most recent stab at producing, CBS' Living Biblically, was canceled after 13 episodes in 2018—he's busy preparing for his biggest role yet: fatherhood. On May 3, 2019, he and girlfriend Alaina Meyer announced that they were expecting their first child together. "We are absolutely over the moon to announce that we will soon be welcoming a little one into this crazy and wonderful world," he wrote on social media, sharing the big news. "There truly is love out there for all. We hope ours is the ember of yours, as we feel yours is the ember of ours."
Mayim Bialik as Amy Farrah Fowler (guest star season 3, starring seasons 4–12): A woman selected by an online dating site as Sheldon's perfect mate. Amy is from Glendale, CA. While she and Sheldon initially share social cluelessness, after befriending Penny and Bernadette she eventually becomes more interested in social and romantic interaction. Her relationship with Sheldon slowly progresses to the point at which Sheldon considers her his girlfriend, eventually they get married. Amy believes she and Penny are best friends, a sentiment that Penny does not initially share. Amy has a Ph.D. in neurobiology.
Although the original pilot was not picked up, its creators were given an opportunity to retool it and produce a second pilot. They brought in the remaining cast and retooled the show to its final format. Katie was replaced by Penny (Kaley Cuoco). The original unaired pilot has never been officially released, but it has circulated on the Internet. On the evolution of the show, Chuck Lorre said, "We did the 'Big Bang Pilot' about two and a half years ago, and it sucked ... but there were two remarkable things that worked perfectly, and that was Johnny and Jim. We rewrote the thing entirely and then we were blessed with Kaley and Simon and Kunal." As to whether the world will ever see the original pilot on a future DVD release, Lorre said, "Wow, that would be something. We will see. Show your failures..."
In the third-season finale, Raj and Howard sign Sheldon up for online dating to find a woman compatible with Sheldon and discover neurobiologist Amy Farrah Fowler. Like him, she has a history of social ineptitude and participates in online dating only to fulfill an agreement with her mother. This spawns a storyline in which Sheldon and Amy communicate daily while insisting to Leonard and Penny that they are not romantically involved. In "The Agreement Dissection", Sheldon and Amy talk in her apartment after a night of dancing and she kisses him on the lips. Instead of getting annoyed, Sheldon says "fascinating" and later asks Amy to be his girlfriend in "The Flaming Spittoon Acquisition". The same night he draws up "The Relationship Agreement" to verify the ground rules of him as her boyfriend and vice versa (similar to his "Roommate Agreement" with Leonard). Amy agrees but later regrets not having had a lawyer read through it.
With Leonard, Howard, Raj, and Amy accomplishing so much on their respective projects, Sheldon is forced to admit he has nothing important upon which to work. He makes Amy leave the apartment for a few days so he can focus, but cannot come up with any ideas and calls his mother as a distraction. Leonard and Amy have fun recreating experiments from when they were growing up, boring Penny, so she eats with Sheldon as he mulls over his scientific studies. Penny helps him realize that his study of dark matter is his rebound science from string theory, which Sheldon admits he never truly disregarded, but explaining string theory to her inspires Sheldon, helping him discover a potential breakthrough in the field. Meanwhile Howard is too busy with his family to be in the band with Raj, so Raj brings in Bert. But, when Howard annoys Bernadette by writing an astronaut-themed musical while she is on bed-rest, she makes him rejoin the band. The three are poorly received at a Bar mitzvah after singing Bert's original song about the boulder from Indiana Jones .
Raj hooks up with a recently separated woman, Nell, after one of his lectures at the planetarium. Her husband, Oliver, confronts Raj at the planetarium and then breaks down over the end of his marriage. After comforting Oliver, Raj talks to Nell and convinces her to give her husband another chance. Meanwhile, after diving once again into string theory and sprawling his work across his and Amy's apartment, Sheldon approaches a reluctant Leonard and Penny and convinces them to let him use his old room to study for a three-day trial period with an agreement to be quiet and stay out of their way. Sheldon surprisingly sticks to this agreement, being a reasonably good guest, which shockingly frustrates Leonard to no end. After Leonard lets out his frustrations, Sheldon then renegotiates the guest tenancy agreement for an extra few days and resumes being his normal demanding self, much to Leonard's relief.
Sheldon and Amy are surprised to find that Wil Wheaton's new Professor Proton show is actually very entertaining and that Wil had Howard on as a guest. On Howard's suggestion, Sheldon apologizes to Wil, mending their friendship, and tells him he wants to be on the show; but Wil asks for Amy. Sheldon tells her to do it, but she says she often doesn't do things to avoid upsetting him. Sheldon is horrified when he realises how selfish he has been, especially when he finds out that the men do the same for him. Sheldon encourages Amy to go on the show to inspire girls to pursue science while trying to control his obvious jealousy for her. Meanwhile, Leonard writes a book about a physicist that solves a murder, the protagonist Logan Dean is based on himself. Bernadette points out Logan's mean boss Illsa is similar to Penny, who thinks it is based on Bernadette, though Leonard does not correct her. However, Bernadette tells Penny the truth, upsetting her and making her mad at Leonard. After calling his mother for advice, Leonard learns that Illsa is actually like her; but abandons the book when he realizes he wrote romantic tension into the relationship between the characters.