---
title: "The Big Bang Theory"
chunk: 3/11
source: "https://en.wikipedia.org/wiki/The_Big_Bang_Theory"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:04:29.021226+00:00"
instance: "kb-cron"
---

The show's pilot episode premiered on September 24, 2007. This was the second pilot produced for the show. A different pilot was produced for the 2006‍–‍07 television season but never aired. The structure of the original unaired pilot was different from the series' eventual form. The only main characters retained in both pilots were Leonard (Johnny Galecki) and Sheldon (Jim Parsons), who are named after Sheldon Leonard, a longtime figure in episodic television as a producer, director, and actor. A minor character, Althea (Vernee Watson), appeared in the first scene of both pilots that was retained generally as-is. The first pilot included two female lead characters - Katie, "a street-hardened, tough-as-nails woman with a vulnerable interior" (played by Canadian actress Amanda Walsh), and Gilda, a scientist colleague and friend of the male characters (played by Iris Bahr). Sheldon and Leonard meet Katie after she breaks up with a boyfriend, and they invite her to share their apartment. Gilda is threatened by Katie's presence. Test audiences reacted negatively to Katie, but they liked Sheldon and Leonard. The original pilot used Thomas Dolby's hit "She Blinded Me with Science" as its theme song.
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..."
The first and second pilots of The Big Bang Theory were directed by James Burrows, who did not continue with the show. The reworked second pilot led to a 13-episode order by CBS on May 14, 2007. Prior to its airing on CBS, the pilot episode was distributed on iTunes free of charge. The show premiered on September 24, 2007, and was picked up for a full 22-episode season on October 19, 2007. The show was filmed in front of a live audience, and it is produced by Chuck Lorre Productions and Warner Bros. Television. Production was halted on November 6, 2007, due to the Writers Guild of America strike. Nearly three months later, on February 4, 2008, the series was temporarily replaced by a short-lived sitcom, Welcome to The Captain. The series returned on March 17, 2008, in an earlier time slot, and ultimately only 17 episodes were produced for the first season.
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. With increasing ratings, the show received a two-year renewal through the 2010‍–‍11 season in 2009. In 2011, the show was picked up for three more seasons. 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. In March 2017, the series was renewed for two additional seasons, bringing its total to 12, and running through the 2018‍–‍19 television season.
Several of the actors on The Big Bang Theory previously worked together on the sitcom Roseanne, including Johnny Galecki, Sara Gilbert, Laurie Metcalf (who plays Sheldon's mother, Mary Cooper), and Meagen Fay (who plays Bernadette's mother). Additionally, Lorre was a writer on the series for several seasons.

=== Science consultants ===

David Saltzberg, a professor of physics and astronomy at the University of California, Los Angeles, checked scripts and provided dialogue, mathematics equations, and diagrams used as props. According to series co-creator Bill Prady, Sheldon was given an actual equation to be worked on throughout the first season, with the actual progress displayed on whiteboards in Sheldon and Leonard's apartment. Saltzberg, who has a Ph.D. in physics, served as the science consultant for the show for six seasons and attended every taping. He saw early versions of scripts that needed scientific information added to them, and he also pointed out where the writers, despite their knowledge of science, had made a mistake. He was usually not needed during a taping unless a lot of science, and especially the whiteboard, was involved.
Saltzberg sometimes consulted with Mayim Bialik, who has a Ph.D. in neuroscience, on the subject of biology.

=== Theme song ===