Quantum Leap is an American television series that was broadcast on NBC from March 26, 1989 to May 5, 1993, for a total of five seasons. The series was created by Donald Bellisario, and starred Scott Bakula as Dr. Sam Beckett, a quantum physicist from the near future who becomes lost in time following a time travel experiment, temporarily taking the places of other people to "put right what once went wrong". Dean Stockwell co-starred as Al Calavicci, Sam's womanizing, cigar-smoking sidekick and best friend, who appeared as a hologram that only Sam, animals, young children, and the mentally ill could see and hear. The series featured a mix of comedy, drama and melodrama, social commentary, nostalgia, and science fiction, which won it a broad range of fans. One of its trademarks is that at the end of each episode, Sam "leaps" into the setting for the next episode, usually uttering a dismayed "Oh, boy!"
Despite struggling on Friday nights in its brief first season, the show was renewed by NBC because of its impressive 18-49 demographics. The series was moved to Wednesdays where it performed well in comparison to other fan-favorite series Wiseguy and China Beach. It was moved twice away from Wednesdays to Fridays in late 1990 and to Tuesdays in late 1992 where it also performed well. The series finale aired in its successful Wednesday slot in May 1993.
The premise for Quantum Leap was inspired by movies like Heaven Can Wait (1978), a remake of the 1941 film Here Comes Mr. Jordan. Donald Bellisario, the show's frontrunner, felt that the concept of a person living in the body of another person to make change for the better, would work well in a science fiction setting, creating the tone for the series.
In the pilot episode, the viewer is introduced to Sam Beckett (Scott Bakula), a gifted physicist working on "Project Quantum Leap" in a concealed government laboratory in the southwestern desert of the United States near the end of the 20th century. Beckett, with his team, had theorized that time travel was possible if the traveler only stayed within the timeframe of their own lifetime. With no successful results so far, Rear Admiral Al Calavicci (Dean Stockwell), Sam's long-time friend and senior officer on the program, is told by the government that they are looking to shut down the funding. Sam refuses to allow this, and before he can be stopped, he enters the Quantum Leap accelerator, disappearing into time.
When Sam recovers, he finds his memories to be incomplete, particularly with knowledge about himself or the project; Al would refer to this as his "swiss-cheesed memory" throughout the series. Sam finds himself in the past as a supersonic jet test pilot, appearing to others and himself in the mirror as another person, but initially attributes this to his amnesia. Al eventually makes contact with Sam, appearing as a hologram that is tuned to Sam's brainwaves so only Sam can see or hear him. Al explains the situation to Sam, revealing that the only way for Sam to return is to correct something that went wrong in the past, according to the project's artificial intelligence "parallel hybrid computer", Ziggy (voiced by co-executive producer Deborah Pratt). Guided by knowledge of what originally transpired stored in Ziggy's databases, as well as Al's own experiences, Sam is able to escape from a crash that originally took the life of the pilot, and changing history; as he does so, he finds himself "leaping", ending up assuming the identity of a different person at a different point in history. Al later states that while they had tried to bring Sam back during this "leap", they were unable to do so, leaving Sam forced to continue leaping until the team can figure out how to bring him back permanently.Sam is capable of using his own abilities, even if this is something his host normally cannot do.