In the show, the song "Soft Kitty" was described by Sheldon as a song sung by his mother when he was ill. Its repeated use in the series popularized the song.[83] A scene depicting the origin of the song in Sheldon's childhood is depicted in an episode of Young Sheldon, which aired on February 1, 2018. It shows Sheldon's mother Mary singing the song to her son, who is suffering with the flu.[84]
After learning Sheldon went behind their backs to work with the military again, Leonard and Howard say Sheldon is like Thomas Edison, taking credit for others' ideas, while they are more like Nikola Tesla. Leonard and Howard bring in Barry Kripke to help create a better idea than Sheldon's, but Kripke goes to the military himself, cutting all three of them out. Meanwhile, Bernadette fears Ruchi is trying to steal her projects at work while she is on maternity leave and enlists Raj to spy on her. Though he finds proof that Ruchi may be stealing from Bernadette, Raj tries to defend Ruchi like a boyfriend would, pointing out Bernadette's hypocrisy as she would most likely have stolen from other people's projects as well. Ruchi is not happy about this and promptly dumps Raj.
The Big Bang Theory premiered in the United States on September 24, 2007 on CBS. The series debuted in Canada on CTV in September 2007.[152] On February 14, 2008, the series debuted in the United Kingdom on channels E4 and Channel 4.[153] In Australia the first seven seasons of the series began airing on the Seven Network and 7mate from October 2015 and also gained the rights to season 8 in 2016, though the Nine Network has rights to air seasons nine & ten.[154][155] On January 22, 2018, it was announced that Nine had acquired the rights to Season 1–8.[156]

Live+7 data is currently available only through May 5, but the top dogs will likely see little change once the final numbers are in for the traditional September-May season. The top gainer in adults 18-49 was NBC’s “This Is Us” with an average lift of 1.8 ratings points. The number two spot was a tie between CBS’ “Big Bang Theory” and NBC’s “Manifest,” with both of those shows adding 1.5 ratings points on average. These numbers do not include “Big Bang Theory’s” series finale, however, which pulled in a 3.1 rating and 18 million viewers in Live+Same Day alone on May 16.


Sheldon's mother Mary refuses to attend his wedding unless he invites his older brother George, with whom he is no longer speaking. Sheldon and Leonard fly to Texas to talk to George, who now owns a chain of tire stores. He refuses to attend and later explains to Leonard and Sheldon that the family sacrificed a lot to fund Sheldon's education, and he was stuck caring for their mother and sister Missy after their father died while Sheldon was in college. Sheldon never thanked him for this. Leonard takes George back to the hotel room where Sheldon apologizes for what he did and the brothers reconcile. George agrees to attend the wedding. Meanwhile, Howard and Bernadette's children contract pinkeye, infecting everyone except Penny, much to Amy's fury.
Warner Bros. Television controls the online rights for the show.[159][160] Full episodes are available at tv.com, while short clips and recently aired full episodes are available on cbs.com.[161] In Canada, recent episode(s) and pictures are available on CTV.ca.[162] Additionally in Canada, the first six seasons are available for streaming on Bell Media's CraveTV.[163] After the show has aired in New Zealand the shows are available in full online at TVNZ's on demand web service.
'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.)
Through the use of his vanity cards at the end of episodes, Lorre alleged that the program had been plagiarized by a show produced and aired in Belarus. Officially titled Теоретики (The Theorists), the show features "clones" of the main characters, a similar opening sequence, and what appears to be a very close Russian translation of the scripts.[207] Lorre expressed annoyance and described his inquiry with the Warner Bros. legal department about options. The television production company and station's close relationship with the Belarus government was cited as the reason that any attempt to claim copyright infringement would be in vain because the company copying the episodes is operated by the government.[208]
David Saltzberg, a professor of physics and astronomy at the University of California, Los Angeles, checks scripts and provides dialogue, mathematics equations, and diagrams used as props.[4] According to executive producer/co-creator Bill Prady, "We're working on giving Sheldon an actual problem that he's going to be working on throughout the [first] season so there's actual progress to the boards ... . We worked hard to get all the science right."[5] David Saltzberg, who has a Ph.D. in physics, has served as the science consultant for the show for six seasons and attends every taping.[23] He sees early versions of scripts which need scientific information added to them, and he also points out where the writers, despite their knowledge of science, have made a mistake. He is usually not needed during a taping unless a lot of science, and especially the whiteboard, is involved.[24]
Two months after the events of "The Change Constant", Sheldon and Leonard repair Sheldon's DNA molecule model as everyone prepares to fly to Sweden for the Nobel Prize award ceremony. Howard and Bernadette nervously leave their kids for the first time with Stuart and Denise, while Raj leaves his dog with Bert. Penny has become pregnant, though she and Leonard are keeping it a secret. On the flight, Raj thinks he spots Sarah Michelle Gellar. Penny's frequent bathroom trips make Sheldon fear she is sick. Leonard reveals the pregnancy to Sheldon, but instead of being excited for Penny, Sheldon is only selfishly relieved that he will not get sick and he exposes the pregnancy, offending Leonard. At the hotel, a series of minor incidents with their kids make Howard and Bernadette want to go home. Much to their dismay, Sheldon is still insensitive. Amy furiously tells Sheldon he broke their friends' hearts and they only tolerate him because he does not intentionally do so, which she also sometimes does. Everyone decides to stay for the ceremony and Raj brings Gellar. After they are awarded their medals, Amy encourages girls to pursue science while Sheldon thanks his family and then individually acknowledges each of his friends and Amy as his other family who always support him. The episode closes with the gang eating in Apartment 4A (an allusion to the final scene in the opening credits) as an acoustic version of the theme song's chorus plays.

In the season eight finale, Sheldon and Amy get into a fight about commitment on their fifth anniversary. Amy tells Sheldon that she needs to think about the future of their relationship, unaware that Sheldon was about to propose to her. Season nine sees Sheldon harassing Amy about making up her mind until she breaks up with him. Both struggle with singlehood and trying to be friends for the next few weeks until they reunite in episode ten and have sex for the first time on Amy's birthday.

The sixth season boasts some of the highest-rated episodes for the show so far, with a then-new series high set with "The Bakersfield Expedition", with 20 million viewers,[97] a first for the series, which along with NCIS, made CBS the first network to have two scripted series reach that large an audience in the same week since 2007. In the sixth season, the show became the highest rated and viewed scripted show in the 18–49 demographic, trailing only the live regular NBC Sunday Night Football coverage,[98][99] and was third in total viewers, trailing NCIS and Sunday Night Football.[100] Season seven of the series opened strong, continuing the success gained in season six, with the second episode of the premiere, "The Deception Verification", setting the new series high in viewers with 20.44 million.[101][102]

After the birth of Michael, Howard and Bernadette are unsure who should stay home with the kids. Howard decides to look after the kids one day to show he has what it takes to care for them. While Bernadette falls back in love with her job on a trip to the office, Howard is quickly tired and realizes he might not have what it takes to be a stay-at-home dad. Howard and Bernadette realize neither them is ready to give up their job.
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.
Sheldon's childhood friend from Texas, Tam, is visiting the university with his son. Sheldon does not want to see him and the others wonder why Sheldon has never mentioned Tam. Tam is unaware Sheldon is angry with him, thinking they just naturally drifted apart. Sheldon's brother George does not know the reason either. Sheldon eventually reveals Tam promised he would move to California with Sheldon, but then got a girlfriend and stayed with her, leaving Sheldon feeling abandoned. Tam and Sheldon make up and Sheldon has Leonard take Tam to the airport. Meanwhile, Penny and Bernadette want to get to know Anu, impressed by her connections in the hotel industry. They tell her embarrassing things about Raj and wonder if they can go out with her again after Raj confronts them.
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