The fourth season's second half began on June 30, 2011. Season 5 began airing on November 3, 2011, at 8:00 p.m. as part of E4's Comedy Thursdays, acting as a lead-in to the channel's newest comedy, Perfect Couples. Episode 19, the highest-viewed episode of the season, attracted 1.4 million viewers.[145] Season 6 premiered on November 15, 2012, with 1.89 million viewers and a further 469,000 on the time shift channel, bringing the total to 2.31 million, E4's highest viewing ratings of 2012, and the highest the channel had received since June 2011. The sixth season returned in mid-2013 to finish airing the remaining episodes.[146] Season 7 premiered on E4 on October 31, 2013 at 8:30pm and hit multiple ratings records this season. The second half of season seven aired in mid 2014.[147] The eighth season premiered on E4 on October 23, 2014 at 8:30 p.m.[148] During its eighth season, The Big Bang Theory shared its 8:30 p.m. time period with fellow CBS comedy, 2 Broke Girls. Following the airing of the first eight episodes of that show's fourth season, The Big Bang Theory returned to finish airing its eighth season on March 19, 2015.[149]
However, no legal action was required to end production of the other show: as soon as it became known that the show was unlicensed, the actors quit and the producers canceled it.[209] Dmitriy Tankovich (who plays Leonard's counterpart, "Seva") said in an interview, "I'm upset. At first, the actors were told all legal issues were resolved. We didn't know it wasn't the case, so when the creators of The Big Bang Theory started talking about the show, I was embarrassed. I can't understand why our people first do, and then think. I consider this to be the rock bottom of my career. And I don't want to take part in a stolen show".[210]
Amy and Howard begin collaborating on a neuroprosthetics project, upsetting Sheldon and Raj, who feel they are not spending as much time with them. When they seek solace with an annoyed Bernadette, she exploits the situation to trick Sheldon into doing Howard's chores. Penny successfully employs the approaches recommended in one of Bernadette's parenting books to deal with Sheldon, but Leonard believes she is coddling Sheldon too much. Sheldon and Raj resolve the issue of missing their significant others by spending time together.
On October 9, 2007, a full-length (1 minute and 45 seconds) version of the song was released commercially.[27] Although some unofficial pages identify the song title as "History of Everything,"[28] the cover art for the single identifies the title as "Big Bang Theory Theme." A music video also was released via special features on The Complete Fourth Season DVD and Blu-ray set.[29][30] The theme was included on the band's greatest hits album, Hits from Yesterday & the Day Before, released on September 27, 2011.[31] In September 2015, TMZ uncovered court documents showing that Steven Page sued former bandmate Robertson over the song, alleging that he was promised 20% of the proceeds, but that Robertson has kept that money entirely for himself.[32]

Leonard's mother Beverly visits, and he is thrilled when she takes an interest in his work. However, when he learns that she is doing research on him for a new parenting book, he is furious. He prepares to tell her how she let him down over the years, but instead chooses to accept and forgive her, and forgive himself for holding onto that resentment for so long. Beverley is touched that he forgave her and they share a genuine hug. Meanwhile, Anu gets a job offer in London. Raj prepares to fly out and propose to her, ready to follow her if she accepts. Howard stops Raj at the airport, saying there is a better match out there for him, convincing Raj to return home. Stuart and Denise are bothered by her creepy roommate Mitch, while Bernadette and Howard are tired of Denise constantly staying overnight with Stuart at their house. Stuart says he is ready to move in with Denise, and they say they love each other while convincing Mitch to move out.
Showrunner Steve Molaro, who took over from Bill Prady with the sixth season, credits some of the show's success to the sitcom's exposure in off-network syndication, particularly on TBS, while Michael Schneider of TV Guide attributes it to the timeslot move two seasons earlier. Chuck Lorre and CBS Entertainment president Nina Tassler also credit the success to the influence of Molaro, in particular the deepening exploration of the firmly established regular characters and their interpersonal relationships, such as the on-again, off-again relationship between Leonard and Penny.[103] Throughout much of the 2012–13 season, The Big Bang Theory placed first in all of syndication ratings, receiving formidable competition from only Judge Judy and Wheel of Fortune (first-run syndication programs). By the end of the 2012–13 television season, The Big Bang Theory had dethroned Judge Judy as the ratings leader in all of syndicated programming with 7.1, Judy descending to second place for that season with a 7.0.[104] The Big Bang Theory did not place first in syndication ratings for the 2013–14 television season, beaten out by Judge Judy.[105]
Filming proceeds smoothly – makeup artists do touch-ups, a prop master replenishes the pickle supply – with humor and camaraderie between takes. When a reshoot is needed because Simon Helberg, who plays Howard, held his napkin in the wrong hand, Kaley Cuoco, who plays Penny, lifts her food box high and mockingly asks, “Does it go over my head? I don’t remember.”
Raj meets with the woman his father set up for him, Anu. Her commanding personality and practical approach to marriage startle Raj but he agrees to go ahead with it. Howard criticizes him but apologizes; he just never expected Raj to give up on romance. Raj admits this to Anu so she proposes to him, and he says yes. Raj also sends out a relationship questionnaire to Leonard and Penny, which soon reveals that Penny does not think she ever wants kids, upsetting Leonard, who would like to have kids someday, and their friends selfishly badger them on the issue. After telling her father Wyatt who is also upset, Leonard tells Penny that he'll be okay with it, as he never thought he'd have her in his life. To get his mind off of it, Penny rents Leonard a Batmobile to drive in and have fun with for the day. Meanwhile, Stuart starts bringing home Denise at night, which is very uncomfortable for Howard and Bernadette. When they also try to have time to themselves, they wake up their kids.
After the strike ended, the show was picked up for a second season, airing in the 2008–2009 season, premiering in the same time slot on September 22, 2008.[17] With increasing ratings, the show received a two-year renewal through the 2010–11 season in 2009.[18][19] In 2011, the show was picked up for three more seasons.[20] In March 2014, the show was renewed again for three more years through the 2016–17 season. This marked the second time the series gained a three-year renewal.[21] In March 2017, the series was renewed for two additional seasons, bringing its total to 12, and running through the 2018–19 television season.[22]
Simon Helberg as Howard Wolowitz:[45] An aerospace engineer who got his Masters at MIT. Howard is Jewish and lived with his mother, Debbie (Carol Ann Susi). Unlike Sheldon, Leonard, Raj, Bernadette and Amy, Howard does not hold a doctorate. He goes into space, training as an astronaut and serving as a payload specialist. Howard initially fancies himself as a womanizer, but he later starts dating Bernadette, and they get engaged and married. Howard also has a tendency to waste money on toys and argues with Bernadette because of his oddly low income as an engineer and her high income as a pharmaceutical biochemist.
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]
Science has also interfered with the characters' romantic lives. Leslie breaks up with Leonard when he sides with Sheldon in his support for string theory rather than loop quantum gravity.[70] When Leonard joins Sheldon, Raj, and Howard on a three-month Arctic research trip, it separates Leonard and Penny at a time when their relationship is budding. When Bernadette takes an interest in Leonard's work, it makes both Penny and Howard envious and results in Howard confronting Leonard, and Penny asking Sheldon to teach her physics.[71] Sheldon and Amy also briefly end their relationship after an argument over which of their fields is superior.[72]
However, no legal action was required to end production of the other show: as soon as it became known that the show was unlicensed, the actors quit and the producers canceled it.[209] Dmitriy Tankovich (who plays Leonard's counterpart, "Seva") said in an interview, "I'm upset. At first, the actors were told all legal issues were resolved. We didn't know it wasn't the case, so when the creators of The Big Bang Theory started talking about the show, I was embarrassed. I can't understand why our people first do, and then think. I consider this to be the rock bottom of my career. And I don't want to take part in a stolen show".[210]
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]

Leonard and Sheldon are brilliant physicists—geniuses in the laboratory but socially challenged everywhere else. Enter beautiful, street-smart neighbor Penny, who aims to teach them a thing or two about life. Despite their on-again, off-again relationship in the past, Leonard and Penny have finally gotten married. Even Sheldon has found a female companion, entering into a "relationship agreement" with neurobiologist Amy Farrah Fowler, and he recently took their relationship to the next level by marrying her after a long courtship. In their free time, Leonard and Sheldon enjoy fantasy role-playing games with their ever-expanding universe of friends, including fellow scientists Koothrappali, Wolowitz, and Wolowitz’s adorable microbiologist wife, Bernadette, who is adjusting to life with their two children.
Howard and Bernadette's new neighbor Andy begins using floodlights mounted on his balcony that encroaches on their rear deck and hot tub. Investigating whether the lights comply with city code, they enlist Sheldon to help them with the paperwork, but Sheldon finds out Howard and Bernadette's own deck is also not code-compliant. He considers turning them in, but ultimately chooses friendship over the rules. He does report Andy though for violating property lines, allowing Howard and Bernadette to enjoy their deck again. Meanwhile, Bert wants to cut into a meteorite with Raj's help, rejecting Leonard's idea to use his laser to do so. Leonard dreams that he opens the meteorite with his laser, becomes possessed by an alien intelligence and eats Bert, Raj and Penny. He later apologizes to Raj and Bert, admitting he was jealous. The possibility of the meteorite unleashing a plague scares Stuart and Denise, who use it as foreplay for procreation, Stuart closing the store on Sheldon when he tries to browse.
Howard and Bernadette learn their second child will be a boy, leading Howard to doubt whether he can be a good father to a son. He and Sheldon go out in the desert to test launch a model rocket, but it explodes, causing him further doubt. On the way home, Howard does a good job coaching Sheldon to drive them home, for which Sheldon tells him he will be a good teacher to his son. Leonard's mother Beverly begins talking to Penny as a friend and confidant, troubling Leonard, especially when he learns that Beverly told Penny that she was proud of her, a level of praise she never bestowed upon Leonard himself. When Leonard confronts Beverly, he is touched when she says that of all of her children's spouses, Penny is the one by whom she is most impressed and that, for this, she is indeed proud of him. Meanwhile, Raj helps Bernadette turn baby girl clothes into boy ones.
Bert asks for Sheldon's help in a geology research project relating to dark matter. Sheldon secretly agrees, but is too embarrassed to admit he is working with rocks. Bert finds out about this and ends their partnership. After talking with Amy, Sheldon goes to apologize, only to find Leonard has taken his place. Meanwhile, Raj runs into Ruchi again and goes out with her, but she does not believe in romantic love. After Howard and Bernadette tell Raj that he can just have sex with Ruchi, he agrees to keep it casual.
"Every heart expanding adventure begins with a single step. This was mine for @bigbangtheory_cbs," Rauch wrote. "My first episode. Or my first 'step-isode' - if you will. The second pic is shortly after I joined the cast (I couldn’t believe I had my very own dressing room)! The friendships and memories that would build from these moments simply overwhelm me."
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.
Science has also interfered with the characters' romantic lives. Leslie breaks up with Leonard when he sides with Sheldon in his support for string theory rather than loop quantum gravity.[70] When Leonard joins Sheldon, Raj, and Howard on a three-month Arctic research trip, it separates Leonard and Penny at a time when their relationship is budding. When Bernadette takes an interest in Leonard's work, it makes both Penny and Howard envious and results in Howard confronting Leonard, and Penny asking Sheldon to teach her physics.[71] Sheldon and Amy also briefly end their relationship after an argument over which of their fields is superior.[72]
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