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 (film) artist.") John Simon felt it was "a regrettable failure, although not a total one. This film is fascinating when it concentrates on apes or machines ... and dreadful when it deals with the in-betweens: humans ... "2001", for all its lively visual and mechanical spectacle, is a kind of space-"Spartacus" and, more pretentious still, a shaggy God story." Eminent historian Arthur M. Schlesinger, Jr. deemed the film "morally pretentious, intellectually obscure and inordinately long ... a film out of control". In a 2001 review the BBC said that its slow pacing often alienates modern audiences more than it did upon