2001: A Space Odyssey (soundtrack) used is Ligeti's "Lux Aeterna" and an electronically altered form of his "Aventures", the last of which was so used without Ligeti's permission and is not listed in the film's credits. Since the film, "Also sprach Zarathustra" has been used in many other contexts. It was used by the BBC and by CTV in Canada as the introductory theme music for their television coverage of the Apollo space missions, as well as stage entrance music for multiple acts including Elvis Presley late in his career. Jazz and rock variants of the theme have also been composed, the most well known
2001: A Space Odyssey (score) music would have been an improvement on the background music that Kubrick finally chose for the film." Conversely, in his notes for the Jerry Goldsmith recording, Kevin Mulhall argued that "there is no doubt that "2001" would have been better if Kubrick had used North's music. Even if one likes some of the choices Kubrick made for certain individual scenes, the eclectic group of classical composers employed by the director... resulted in a disturbing melange of sounds and styles overall." Film critic Roger Ebert noted that North's rejected score contains emotional cues to the viewer while the final music selections