The Big Bang Theory

• 1. Introduction

  ›

  The Big Bang Theory debuted on CBS on the 24th of September 2007, the same night a different kind of television experiment began. Two physicists, a waitress, and a laugh track walked into a Pasadena apartment building - and over the next 12 seasons and 279 episodes, that setup became one of the most-watched comedies in American television history. By its eleventh season, the show had climbed to the number one spot in the ratings. Its lead actor, Jim Parsons, would win four Emmy Awards for the same role. The question the show posed from the start was deceptively simple: could a comedy built around science and social awkwardness find a mass audience? The answers, which involve a rejected first pilot, a theme song born from a freestyle rap, and a Belarus plagiarism scandal, reveal a show that almost never existed in the form the world came to know.

• 2. The Pilot That Never Aired

  ›

  Before the show that aired on the 24th of September 2007, there was a completely different show. The original unaired pilot, produced for the 2006-07 television season, featured two female lead characters neither of whom survived the retooling. Katie was described as "a street-hardened, tough-as-nails woman with a vulnerable interior" and was played by Amanda Walsh; the scientist Gilda was played by Iris Bahr. The version of Penny that audiences came to know did not exist in this first attempt. Test audiences reacted negatively to Katie, though they responded well to the two physicists played by Johnny Galecki and Jim Parsons. Thomas Dolby's hit "She Blinded Me with Science" served as the theme song in that original version. Rather than abandon the project, CBS gave creators Chuck Lorre and Bill Prady the chance to retool it entirely. Lorre later described the original pilot bluntly: "We did the 'Big Bang Pilot' about two and a half years ago, and it sucked." Both pilots were directed by James Burrows, who then stepped away from the series. The reworked version earned a 13-episode order from CBS on the 14th of May 2007, before the revamped pilot had even aired.

• 3. Building the Characters

  ›

  Leonard Hofstadter, played by Johnny Galecki, holds an IQ of 173 and received his doctorate at age 24. His roommate Sheldon Cooper, played by Jim Parsons, is a theoretical physicist from Galveston, Texas, who began college at eleven and earned his doctorate at sixteen, with an IQ of 187. Their names are not accidental - both characters are named after Sheldon Leonard, a producer, director, and actor who was a longtime figure in episodic television. Penny, played by Kaley Cuoco, comes from Omaha, Nebraska, and works at The Cheesecake Factory before eventually becoming a pharmaceutical sales representative. Howard Wolowitz, played by Simon Helberg, holds a master's degree from MIT rather than a doctorate, a distinction the show treats as a recurring point of tension among the group. Raj Koothrappali, played by Kunal Nayyar, is a particle astrophysicist from New Delhi who begins the series unable to speak to women unless he has consumed alcohol. As the show developed, three supporting characters were elevated to main cast status: neuroscientist Amy Farrah Fowler, played by Mayim Bialik, who holds a Ph.D. in neurobiology; microbiologist Bernadette Rostenkowski, played by Melissa Rauch; and comic book store owner Stuart Bloom, played by Kevin Sussman, a graduate of the Rhode Island School of Design.

• 4. Science as Backbone

  ›

  David Saltzberg, a professor of physics and astronomy at UCLA with a Ph.D. in physics, served as the show's science consultant for six seasons and attended every taping. According to co-creator Bill Prady, Sheldon was given an actual equation to work on throughout the first season, with the real progress displayed on whiteboards inside the apartment set. Saltzberg reviewed early script drafts, supplied dialogue and mathematics equations, and corrected errors the writers made despite their own knowledge of science. He sometimes consulted with Mayim Bialik, who holds a real Ph.D. in neuroscience, on biological questions. The show brought in real scientists as guest stars throughout its run: Nobel laureate astrophysicist George Smoot appeared in the second season, cosmologist Stephen Hawking made a guest appearance in the fifth season and returned in the eighth, and Nobel laureate chemical engineer Frances Arnold portrayed herself in the twelfth season. Neil deGrasse Tyson appeared in the fourth and twelfth seasons. NASA astronaut Buzz Aldrin had a cameo in the sixth season, while fellow astronaut Michael J. Massimino appeared multiple times in the fifth and sixth seasons as Howard's colleague. The science was not merely decorative - Leslie Winkle breaks up with Leonard specifically because he sides with Sheldon on string theory over loop quantum gravity.

• 5. Theme Song and the Barenaked Ladies

  ›

  The Barenaked Ladies, a Canadian alternative rock band, wrote and recorded the show's theme song after co-lead singer Ed Robertson was approached by Lorre and Prady following one of the band's concerts in Los Angeles. What made the commission unusual was a coincidence Robertson brought to the meeting: he had recently read Simon Singh's 2004 book Big Bang, and at the very concert Lorre and Prady attended, Robertson had improvised a freestyle rap about the origins of the universe. The producers phoned him shortly after the show to commission the song. Robertson had been asked to write music for other projects before, only to be rejected in favor of other artists, so he agreed only after confirming that Lorre and Prady had not simultaneously approached anyone else. The original unaired pilot had used Thomas Dolby's song instead. A full-length version of the new theme, running one minute and 45 seconds, was released commercially in October 2007. The song's official title, as printed on the cover art for the single, is "Big Bang Theory Theme," not "History of Everything" as some unofficial sources have claimed. The song was later included on the band's greatest hits album, released on the 27th of September 2011. In September 2015, former bandmate Steven Page sued Robertson, alleging that he had been promised 20 percent of the proceeds from the song.

• 6. Ratings Rise and Salary Wars

  ›

  The show ranked 68th in its first season, failing to crack the top 50 in American ratings. By season three, it had become CBS's highest-rated show on its premiere night, drawing 12.83 million viewers. CBS moved the series to Thursdays at 8:00 ET for the 2010-11 season, placing it in direct competition with NBC's Comedy Block and Fox's American Idol. During its fourth season, it surpassed Two and a Half Men to become television's highest-rated comedy, a position that series had held for eight years. The sixth season set a then-series record of 20 million viewers for a single episode. For the main three stars - Galecki, Parsons, and Cuoco - salaries rose from up to $60,000 per episode in the first three seasons, to $200,000 in the fourth, climbing by $50,000 per season to reach $350,000 in the seventh season. Contracts signed in August 2014 brought the three principal actors to an estimated $1 million per episode for three years. Helberg and Nayyar negotiated their own renegotiation around the same time; the studio threatened to write their characters out of the series if no deal was reached before season eight began production. By season ten, both reached $1 million per episode under a clause in their 2014 deals. In March 2017, the five principal cast members voluntarily took a 10 percent pay cut, reducing their pay to $900,000 per episode, to allow Bialik and Rauch to earn $500,000 per episode each.

• 7. The Franchise That Followed

  ›

  The initial idea for a Sheldon-centered prequel series came from Jim Parsons himself, who passed it to the show's producers. Young Sheldon was ordered by CBS on the 13th of March 2017, with Iain Armitage cast as the 9-year-old Sheldon Cooper attending high school in East Texas. Zoe Perry, cast as Mary Cooper, is the real-life daughter of Laurie Metcalf, who plays the same character on the original series. Parsons narrated Young Sheldon as the adult Sheldon throughout its run, which concluded on the 16th of May 2024 with an hour-long finale that included a cameo from Parsons and Bialik in character. The finale also revealed the framing device: Young Sheldon had been a memoir written by Sheldon himself. The third series in the franchise, Georgie and Mandy's First Marriage, premiered on CBS on the 17th of October 2024, following Sheldon's older brother. A fourth series, Stuart Fails to Save the Universe, starring Kevin Sussman alongside Lauren Lapkus and Brian Posehn, had filmed as of early 2026 and involves Stuart accidentally causing a multiverse Armageddon after breaking a device built by Sheldon and Leonard. John Ross Bowie will reprise his role as Barry Kripke in that series.

• 8. The Belarus Affair

  ›

  Through the one-second vanity cards that close every episode, Chuck Lorre disclosed that the show had been plagiarized by a Belarusian production in 2010. The series, officially titled The Theorists, featured near-identical characters, a similar opening sequence, and what appeared to be a close Russian translation of the original scripts. Lorre's attempts to pursue legal action ran into a structural obstacle: the production company responsible had a close relationship with the Belarusian government, which itself operated the broadcaster, making copyright claims effectively unenforceable through conventional channels. The situation resolved without litigation. Once the series' unlicensed status became publicly known, the cast quit and the producers cancelled the show voluntarily. An actor who played the Leonard counterpart, named Seva, spoke publicly about the experience: "I'm upset. At first, the actors were told all legal issues were resolved. We didn't know it wasn't the case... I consider this to be the rock bottom of my career. And I don't want to take part in a stolen show." The original series finale, which aired on the 16th of May 2019, ended with a vanity card reading simply: "The End."